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Is Knowledge Justified True Belief?

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The tripartite theory of knowledge, strengths of the justified true belief theory, criticisms and challenges, alternative theories of knowledge.

Belief: The individual must believe the proposition or statement in question. In other words, knowledge requires a mental commitment to the truth of a claim.
Truth: The belief must align with objective reality; it must be true. Knowledge cannot be based on false or mistaken beliefs.
Justification: The belief must be justified by adequate evidence or reasoning. In other words, the person holding the belief should have good reasons for accepting it as true.

Reflects Common Understanding:

Accounts for fallibility:, objective standard:, gettier problems:, justification problem:, belief vs. acceptance:.

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7.2 Knowledge

Learning objectives.

By the end of this section, you will be able to:

Identify and explain the elements of Plato’s traditional account of knowledge.
Describe the Gettier problem.
Recall a Gettier case and explain how it is a counterexample to the traditional account of knowledge.
Identify and explain a way of thinking that attempts to solve the Gettier problem.

What does it mean to say that one knows something? Knowledge is an important concept in all areas of thought. Knowledge is the goal and therefore enjoys a special status. Investigating the nature of knowledge reveals the importance of other concepts that are key to epistemological theorizing—justification in particular.

Plato and the Traditional Account of Knowledge

Plato , one of the most important of the Greek philosophers, hypothesized that knowledge is justified true belief. Plato’s analysis is known as the traditional account of knowledge . Plato’s definition is that a person S knows proposition P if and only if

S believes P, and
S is justified in believing P (Plato 1997b).

Plato’s hypothesis on knowledge, often referred to as the JTB account (because it is “ justified true belief ”), is highly intuitive. To say “John knows P, but he does not believe P” sounds wrong. In order to know something, a subject must first believe it. And one also cannot say “Ali knows P, but P is false.” A person simply cannot have knowledge of false things. Knowledge requires truth. Last, someone should not claim to know P if they have no reason to believe P (a reason to believe being justification for P).

Problems with the Traditional Account of Knowledge

Amazingly, Plato ’s view that knowledge is justified true belief was generally accepted until the 20th century (over 2,000 years!). But once this analysis was questioned, a flurry of developments occurred within epistemology in the latter half of the 20th century. This section discusses the counterexample method at play in the dialectic concerning what knowledge is. Plato’s JTB analysis was the first to come under scrutiny.

In 1963, American philosopher Edmund Gettier (1927–2021) published a short paper titled “Is Justified True Belief Knowledge?,” which upended the JTB canon in Western philosophy. Gettier presents two counterexamples to Plato’s analysis of knowledge. In these counterexamples, a person seems to have a justified true belief, yet they do not seem to have knowledge. While Gettier is credited with the first popular counterexample to the JTB account, he was not the first philosopher to articulate a counterexample that calls into question Plato’s analysis. But because Gettier published the first influential account, any example that seems to undermine Plato’s JTB account of knowledge is called a Gettier case . Gettier cases illustrate the inadequacy of the JTB account—a problem referred to as the Gettier problem .

Dharmakīrti’s Mirage

The earliest known Gettier case, long predating the term, was conceived by the eighth century Indian Buddhist philosopher Dharmakīrti . Dharmakīrti’s case asks one to imagine a weary nomad traveling across the desert in search of water (Dreyfus 1997). The traveler crests a mountain and sees what appears to be an oasis in the valley below, and so comes to believe that there is water in the valley. However, the oasis is just a mirage. Yet there is water in the valley, but it is just beneath the surface of the land where the mirage is. The traveler is justified in believing there is water in the valley due to sensory experience. Furthermore, it is true that there is water in the valley. However, the traveler’s belief does not seem to count as knowledge. Dharmakīrti’s conclusion is that the traveler cannot be said to know there is water in the valley because the traveler’s reason for believing that there is water in the valley is an illusory mirage.

Russell’s Case

Perhaps you’ve heard the phrase “Even a broken clock is right twice a day.” The next case relies on this fact about broken clocks. In 1948, Bertrand Russell offered a case in which a man looks up at a stopped clock at exactly the correct time:

There is the man who looks at a clock which is not going, though he thinks it is, and who happens to look at it at the moment when it is right; this man acquires a true belief as to the time of day, but cannot be said to have knowledge. (Russell 1948, 154)

Imagine that the clock the man looks at is known for its reliability. Hence, the man is justified in believing that the time is, for example, 4:30. And, as the cases supposes, it is true that it is 4:30. However, given that the clock is not working and that the man happens to look up at one of the two times a day that the clock is correct, it is only a matter of luck that his belief happens to be true. Hence, Russell concludes that the man cannot be said to know the correct time.

Fake Barn Country

The last Gettier case we will look at is from American philosopher Carl Ginet (b. 1932) (Goldman 1976). Henry is driving through a bucolic area of farmland and barns. What he doesn’t realize, however, is that the area is currently being used as a movie set, and all the barns save one are actually barn facades. While looking at one of the barns, Henry says to himself, “That is a barn.” Luckily for Henry, the one he points to is the one true barn in the area. Again, all the conditions in Plato’s analysis of knowledge are met. It is true that Henry is looking at a real barn, and he believes it is a barn. Furthermore, he has come to this belief utilizing justifiable means—he is using his vision, in normal lighting, to identify a common object (a barn). Yet one cannot reasonably say that Henry knows the barn is a barn because he could have, by chance, accidentally identified one of the fake barns as a true barn. He fortunately happens to pick the one true barn.

Table 7.2 summarizes the Gettier cases discussed in this chapter.

Fixing Plato’s Traditional Account of Knowledge

Gettier cases demonstrate that Plato ’s traditional account of knowledge as justified true belief is wrong. Specifically, Gettier cases show that a belief being true and justified is not sufficient for that belief to count as knowledge. In all the cases discussed, the subject seems to have a justified true belief but not knowledge. Notice that this does not mean that belief, truth, or justification is not necessary for knowledge. Indeed, when speaking of propositional knowledge, all philosophers grant that belief and truth are necessary conditions for knowledge. A person cannot be said to know a proposition if they do not believe that proposition. And clearly, if a belief is to count as knowledge, then that believe simply cannot be false. Accordingly, attempts to solve the Gettier problem do one of two things: either they replace the justification condition with something more robust, or they add a fourth condition to JTB to make the account sufficient.

No False Premises

In Dharmakīrti’s case, the nomad believes there is water in the valley based on the false belief that a mirage is an oasis. And in Russell’s case, the man bases his true belief about the time on the false belief that the clock he’s looking at is working. In both cases, the inference that leads to the true belief passes through false premises. In response to this fact, American philosopher Gilbert Harman (1928–2021) suggested adding a condition to the JTB account that he termed “no false lemmas” (Harman 1973). A false lemma is a false premise, or step in the reasoning process. Harman’s fourth condition is that a person’s belief cannot be based on an inference that uses false premises. According to Harman, S knows P if and only if (1) P is true, (2) S believes P, (3) S is justified in believing P, and (4) S did not infer P from any falsehoods.

Harman theorized that many counterexamples to the traditional account share a similar feature: the truth of the belief is not appropriately connected to the evidence used to deduce that belief. Going back to Dharmakīrti ’s case, what makes the statement “There’s water in the valley” true is the fact that there is water below the surface. However, the nomad comes to believe that there is water based on the mistaken belief that a mirage is an oasis, so what makes the belief true is not connected to the reason the nomad believes it. If Harman’s condition that the reasoning that leads to belief cannot pass through false steps is added, then the nomad’s belief no longer counts as knowledge.

Harman ’s emendation explains why the nomad does not have knowledge and accounts for the intuition that the man in Russell’s case does not actually know what time it is. However, this cannot take care of all Gettier cases . Consider the case of Henry in fake barn country. Henry comes to believe he is looking at a barn based on his perceptual experience of the barn in front of him. And Henry does look at a real barn. He does not reason through any false premises, such as “All the structures on my drive are barns.” His inference flows directly from his perceptual experience of a real barn. Yet it is a matter of luck that Henry isn’t looking at one of the many barn facades in the area, so his belief still does not seem to count as knowledge. Because Harman’s account is vulnerable to the barn counterexample, it does not solve the Gettier problem.

Ruling Out Defeaters and Alternatives

While driving through fake barn country, Henry happens to form the belief “That is a barn” when looking at the only real barn in the area. While Henry’s belief is not based on false premises, there still seems to be something wrong with it. Why? The problem is that certain facts about Henry’s environment (that it is filled with barn facades), if known, would undermine his confidence in the belief. That the area is predominantly filled with barn facades is what is known as a defeater because it serves to defeat the justification for his belief. Contemporary American philosophers Keith Lehrer and Thomas Paxson Jr. suggest that justified true belief is knowledge as long as there are no existing defeaters of the belief (Lehrer and Paxson 1969). S has knowledge that P if and only if (1) P is true, (2) S believes P, (3) S is justified in believing P, and (4) there exist no defeaters for P. The added fourth condition means that there cannot exist evidence that, if believed by S, would undermine S’s justification.

The “no defeaters” condition solves all three Gettier cases discussed so far because in each case, there exists evidence that, if possessed by the subject, would undermine their justification. Henry cannot be said to know he’s looking at a barn because of the evidence that most of the barns in the area are fake, and Russell’s man doesn’t know the time because the clock is stopped. The “no defeaters” condition thus helps solve many Gettier cases. However, we now need a thorough account of when evidence counts as a defeater . We are told that a defeater is evidence that would undermine a person’s justification but not how it does this. It cannot be that all evidence that weakens a belief is a defeater because this would make knowledge attainment much more difficult. For many of our justified true beliefs , there exists some evidence that we are unaware of that could weaken our justification. For example, we get many beliefs from other people. Research indicates that people tell an average of one lie per day (DePaulo et al. 1996; Serota, Levine, and Boster 2010). So when someone tells you something in conversation, often it is true that the person has lied once today. Is the evidence that a person has lied once today enough evidence to undermine your justification for believing what they tell you?

Notice that because a defeater is evidence that would undermine a person’s justification, what counts as a defeater depends on what justification is. Of the theories of knowledge examined so far, all of them treat justification as basic. They state that a belief must be justified but not how to measure or determine justification.

The Problem with Justification

The traditional analysis of knowledge explains that knowledge is justified true belief. But even if we accept this definition, we could still wonder whether a true belief is knowledge because we may wonder if it is justified. What counts as justification ? Justification is a rather broad concept. Instead of simply stating that justification is necessary for knowledge, perhaps a thorough account of knowledge ought to instead spell out what this means. The next section looks more deeply at how to understand justification and how some theorists suggest replacing the justification condition in order to solve the Gettier problem.

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Knowledge as Justified True Belief

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Published: 19 February 2021
Volume 88 , pages 531–549, ( 2023 )

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What is knowledge? I this paper I defend the claim that knowledge is justified true belief by arguing that, contrary to common belief, Gettier cases do not refute it. My defence will be of the anti-luck kind: I will argue that (1) Gettier cases necessarily involve veritic luck, and (2) that a plausible version of reliabilism excludes veritic luck. There is thus a prominent and plausible account of justification according to which Gettier cases do not feature justified beliefs, and therefore, do not present counterexamples to the tripartite analysis. I defend the account of justification against objections, and contrast my defence of the tripartite analysis to similar ones from the literature. I close by considering some implications of this way of thinking about justification and knowledge.

Knowledge as Objectively Justified Belief

Competence to know.

Justification

Avoid common mistakes on your manuscript.

1 Introduction

What is knowledge? In this paper I defend the claim that knowledge is justified true belief. This account is well-known as the ‘classical’ or ‘tripartite’ analysis of knowledge. Many epistemologists, however, regard the claim to be plainly false. Footnote 1 In this paper I aim to show that the tripartite analysis of knowledge should be given more credit than the current state of the debate affords it.

My defence will be indirect: I will argue that, on a plausible interpretation of the justification condition, Gettier cases do not present counterexamples to the tripartite analysis of knowledge. If successful, my argument shows that the tripartite analysis is more plausible than commonly supposed, not that it is beyond question.

The paper is structured as follows. In Sect. 2 , I show that Gettier cases necessarily involve a kind of luck known as veritic luck . In Sect. 3 , I provide a plausible interpretation of reliabilist justification that excludes veritic luck. In Sect. 4 , I defend this interpretation against objections. In Sect. 5 , I compare my defence of the tripartite analysis against alternatives from the literature. In Sect. 6 , I consider some implications of the proposed way of thinking about justification and knowledge.

2 Gettier Cases Involve Veritic Luck

In this section I shall argue that Gettier cases necessarily involve a particular kind of luck: veritic luck. Footnote 2

I will be working with a modal account of luck (MAL) (Pritchard 2005 , 2014 ). According to this account, luck depends on the modal profile of an event: the distribution of possible worlds where the event does and does not occur. An event is a case of luck only if it occurs in the actual world, but fails to occur in (enough) nearby possible worlds, where, where a world is ‘closer’ to the actual world the more similar it is to it (Pritchard 2005 , p. 128; Sainsbury 1997 , p. 913). Nearby worlds represent ‘easy’ possibilities, since not much would need to change to the actual world for the event occurring in a nearby world to occur. On this interpretation, nothing is more easily possible than what happens in the actual world, since no world is closer (more similar) to the actual world than the actual world itself. The account correctly classifies paradigm cases of luck, like winning the lottery and finding a treasure, because such events could have easily failed to occur, in the sense that not much would need to change to the actual world for one to fail to win the lottery or fail to find the treasure.

Luck is relative both to a set of agents and to a set of ‘initial conditions’. It is relative to agents because the same event may be lucky for one agent but not for another. The reason for this is that events need to be of some positive significance to some agent in order to be lucky: an avalanche on the South pole, no matter how easily it could have failed to occur, is not a case of luck if no one cares. Footnote 3

Whether an event is a case of luck also depends on what we take to be its relevant initial conditions. For example, keeping fixed the complete state of the universe just prior to buying the ticket, my lottery win may well be fully determined, and therefore not a case of luck. However, fix only that I bought a random ticket, and under these conditions it will be easily possible for me to fail to win the lottery.

We arrive at the following definition of luck:

LUCK Event E is lucky for agent S under conditions I iff:

E is significant to S (or would be significant, were S to be availed of the relevant facts), and

E actually occurs, but could have easily failed to occur under conditions I.

Veritic luck is a special kind of luck. It attaches to beliefs that are true but produced in a way that could have easily produced a false belief instead.

VERITIC LUCK : A belief is veritically lucky if and only if it is a matter of luck that the method one used to form one’s belief produced a true belief. Footnote 4

Suppose that I form a belief that the number of stars is even on the basis of a simple guess. My belief may be true. If it is, then it is veritically lucky, because it is produced in a way that could have easily resulted in me forming the false belief that the number of stars is uneven. Footnote 5 As is common in the literature, I will assume that the formation of a true belief is of at least some significance to the relevant agents involved, and that the relevant initial conditions for veritic luck include the agent’s method of belief formation. Footnote 6

Why think that Gettier cases necessarily involve veritic luck? Consider one of Gettier’s own cases (somewhat abbreviated for ease of use):

DISJUNCTION : Smith has excellent evidence for the proposition that Jones owns a Ford, and forms the corresponding belief. From this proposition, Smith competently deduces the further proposition that either Jones owns a Ford, or Brown is in Barcelona, and again forms the corresponding belief. Smith has no evidence whatsoever that indicates that Brown is in fact in Barcelona, and so formulates the second disjunct quite at random. Now suppose that through some elaborate deception, all Smith’s evidence for believing that Jones owns a Ford is misleading, and Jones in fact does not own a Ford at all. Suppose further, however, that Brown is in Barcelona at the moment Smith forms his belief in the disjunction. His belief thus ends up being true.

It is widely accepted that in the above case Smith does not know that either Jones owns a Ford or Brown is in Barcelona. Note, however, that Smith’s belief-forming method could have easily produced a false belief. For example, Smith could have easily formed the false belief that either Jones owns a Ford or Brown is in London. Footnote 7 This Gettier case thus clearly involves veritic luck.

The above is just one example. Linda Zagzebski provides a general formula for generating Gettier cases (Zagzebski 1994 ). If we can show that, following this formula, one will be guaranteed to end up with a belief that is veritically lucky, this will suffice to show that all Gettier cases (at least of the standard sort covered by Zagzebski’s formula) involve veritic luck.

Zagzebski’s recipe is the following: take any non-factive epistemic condition you like and construct a case such that a given subject’s true belief satisfies it. Footnote 8 Then, modify the case such that accidentally, satisfying the epistemic condition does not lead you to form a true belief. Finally, make it so that as a second case of luck (unconnected to your cognitive activity), you end up with a true belief nonetheless (Zagzebski 1994 , p. 66). In these cases, the subject will, according to Zagzebski, end up with a belief that satisfies the preferred conditions for knowledge, but will still fail to qualify as such. In short, the subject will end up with a Gettiered belief.

A belief is veritically lucky if one’s belief-forming method actually produced a true belief but could have easily produced a false belief instead. In Gettier cases, according to Zagzebski, “an accident of bad luck is cancelled out by an accident of good luck. The right goal is reached, but only by chance” (Zagzebski 1994 ) Here the right goal is the formation of a true belief. It is reached by chance because one’s method of belief formation is such that in the case at hand, it does nothing to lead you to form a true belief. In combination with the second kind of luck, this means not much would need to change to the actual world for the method to produce a false belief instead. Thus, it follows that all Gettier cases, or at least the ones that can be constructed using Zagzebski’s method, will feature veritic luck. Footnote 9

3 A Modal Interpretation of Reliabilism

In the previous section I argued that Gettier cases involve veritic luck. In this section and the next, I will defend the following claim:

JUSTIFICATION A belief is justified only if it is not veritically lucky.

The account is original in that anti-luck conditions are usually formulated as conditions on knowledge, rather than on justification (Littlejohn 2014 ; Pritchard 2005 ; Williamson 2009 ). Under the assumption that knowledge requires justification, our account will explain why there is such an anti-luck condition on knowledge. But depending on how these authors flesh out their notion of justification, our account may or may not be compatible with theirs. In any case, in this section I will argue specifically for an anti-luck condition on justification.

I will do so by first presenting a modal interpretation of Goldman’s famous reliabilist theory of justification, an interpretation on which no justified belief is veritically lucky. While I believe many of Goldman’s writings are compatible with such a reading of reliabilism, this is rarely noted, and the modal interpretation of reliabilism is not widely endorsed in the literature. I will therefore provide further support for this interpretation in the next section, by considering and diffusing main objections to it.

First, some preliminaries. The relevant kind of justification at issue in JUSTIFICATION is doxastic justification , a property of beliefs, rather than propositional justification , which is a property of propositions. Footnote 10 Further, the claim specifies a necessary condition for doxastic justification, not a sufficient one. It may very well be that there are other necessary conditions on doxastic justification, besides the one proposed in this paper. It should finally be noted that whether a belief is veritically lucky depends on factors other than the believing agent’s mental states or reflectively accessible information, so that the concept of justification we are working with here in this paper is externalist . Footnote 11

JUSTIFICATION is supported by one of the most prominent accounts of doxastic justification in the literature: Goldman’s process reliabilism ( 1979 , 1994 ). Footnote 12 While Goldman does not explicitly endorse the claim that justification excludes veritic luck in his writings, in this section I will argue that there is a plausible interpretation of his account that does.

Consider first Goldman’s reliabilist account of justification:

RELIABILISM S’s belief in p is justified IFF it is caused (or causally sustained) by a reliable cognitive process, or a history of reliable processes. (Goldman 1994 )

The general idea behind reliabilism is that a belief is justified if and only if it is caused by a process that reliably produces true beliefs. Thus, beliefs formed on the basis of perception under normal circumstances will come out as justified (as they should) because under normal circumstances perception reliably causes true beliefs. Conversely, beliefs formed on the basis of tea-leaf reading will not come out as justified (as they should), because this process will not produce a high ratio of true over false belief.

There are different ways to understand the relevant truth/falsity ratio. First, we can understand it to concern actual operations of the process, or also counterfactual ones. This gives us the difference between frequency and modal interpretations of reliabilism. On a frequency account, what matters is whether the process in actual operation produces enough truth over falsity, whereas on the modal interpretation, what matters is whether the process would produce truth over falsity, even if it actually does not operate at all, or actually fails to produce enough truth over falsity.

We may further distinguish global from local reliability. A process is globally reliable if and only if it produces enough truth over falsity in all its possible or actual applications, whereas it is locally reliable if and only if it produces (or would produce) enough truth over falsity in situations similar enough to the actual case. Thus, ‘going by eyesight’ may be a globally reliable process or method, but it will not be a locally reliable method if one is currently in barn-façade county and forming beliefs about the presence of barns. Generally, (we presume,) trusting one’s eyes will produce a high ratio of true beliefs over false ones, but in the context of barn-façade county, looks are deceiving, and so in similar circumstances one would form many false beliefs in the same way.

Which of these notions is relevant for justification? According to Timothy Williamson, reliability should be understood in modal rather than frequency terms:

Reliability and unreliability, stability and instability, safety and danger, robustness and fragility are modal states. They concern what could easily have happened. They depend on what happens under small variations in the initial conditions. (Williamson 2000 )

In the epistemic context, there are good reasons for doing so, in particular that we would not want to say that belief-forming methods that are only used once are either completely reliable or completely unreliable. Relatedly, if I follow a version of the gambler’s fallacy consistently, and believe that the next number of a roulette wheel will be the number that has not come up for the longest amount of runs, this method will not produce justified beliefs, even if in the actual circumstances in which I apply it, it actually does produce mostly true beliefs, What matters for justification seems to be whether the method could have easily produced false belief, not whether it has actually done so.

We can find a similar modal interpretation of reliability in the work of Goldman, specifically a local modal account, when he speaks about the reliability required for knowledge:

… a cognitive mechanism or process is reliable if it not only produces true beliefs in actual situations, but would produce true beliefs, or at least inhibit false beliefs, in relevant counterfactual situations. (Goldman 1976 )

The reliability theories [of knowledge] presented above focus on modal reliability, on getting truth and avoiding error in possible worlds with specified relations to the actual one. They also focus on local reliability, that is, truth-acquisition in scenarios linked to the specific scenario in question as opposed to truth-getting by a process or method over a wide range of cases. (Goldman and Beddor 2016 )

At first sight, it is not clear whether the kind of reliability required for knowledge is the same as that required for justification according to Goldman. For example, in Epistemology and cognition, when he speaks explicitly about the reliability required for justification, Goldman again opts for modal condition, but one that is slightly more difficult to place on the global–local axis, since it makes the required reliability dependent on what happens in so-called ‘normal’ worlds—worlds that conform to our current beliefs about the world ( 1986 , p. 107). Such ‘normic’ reliability conditions on justification receive support from recent defenses by Jarett Leplin and Martin Smith (Leplin 2009 ; Smith 2016 ).

Normic reliability resembles local reliability since both depend on what happens in a restricted class of worlds rather than all possible worlds. But it differs from local accounts of reliability in that it anchors the relevant set of worlds not to the actual world but to a class of ‘normal worlds’, where normal worlds are worlds compatible with our current beliefs about the world. Thus, if we are envatted brains, we may continue to believe as we do, and our methods would still be justified according to the normic reliability criterion (for these methods are reliable in worlds compatible with our current beliefs about the world). This is how normic reliabilists accommodate the intuition that the beliefs of BIV’s are justified.

In this paper, I opt for a local conception of the kind of reliability required for justification rather than a normic conception. Normic accounts unduly prioritize the epistemic relevance of (our beliefs about) our current world. It is a guiding thought behind the present paper that methods that produce justified beliefs do so because they ensure a proper fit between our beliefs and the world. If the notion of reliability has any relevance in epistemology it is to designate that our methods are guides to truth. That some method is reliable in contexts in which it will never be used seems of little epistemic relevance. Normic reliability accounts predict that BIV’s are justified in using our empirical belief-forming methods even if the relevant subject is envatted from the moment they are born to the moment they die, and these empirical methods never produce a single true belief. Ideally, we want a general analysis that has sensible conditions on knowledge and justification not just for us, but for creatures cognizing in vastly different epistemic contexts as well. It is hard to imagine why such creatures would accord any epistemic relevance to methods that are reliable at our world only. What their epistemologists would care about is reliability in their context, and so I think it is local reliability that ultimately matters for a general theory of justification.

In any case, Goldman abandoned his normic account in favor of a distinction between strong and weak justification (Goldman 1988 ). A belief is said to be strongly justified just in case it is produced by an (epistemically) adequate method, whereas it is said to be weakly justified just in case the believer is (epistemically) blameless in so believing. Since no method for which one is epistemically to blame is epistemically adequate, strong justification implies weak justification, but not the other way around, for adequate methods may require more than just blameless believing.

What more is required? Here Goldman is very explicit. For any belief-forming process, we should assess its “rightness [strong justification] in [world] W not simply by its performance in W, but by its performance in a set of worlds very close to W” (Goldman 1988 , p. 63). This clearly indicates that the reliability that Goldman thinks is required for strong justification is local modal reliability.

The same kind of reliability is not required for weak justification, however, as becomes clear from Goldman’s treatment of the Cartesian demon case (a variant of the envatted brain case discussed above): “The present version of reliabilism accommodates the intuition that demon-world believers have justified beliefs by granting that they have weakly justified beliefs” (Goldman 1988 , pp. 62, 63). Obviously, demon-world victims do not have beliefs that are produced by processes that perform well in their actual world as well as in a set of worlds close to the demon-world. This does not stop their beliefs from being weakly justified according to Goldman, so weak justification does not require local modal reliability.

Weak justification thus does not eliminate veritic luck. But with our definitions of veritic luck and local modal reliability in hand, it is easy to see that strong justification, as well as any account that requires local modal reliability, does entail the absence of veritic luck.

First, a method that is locally modally reliable is a process or method that produces a high ratio of truth over falsity situations similar to the actual case. Second, a belief is veritically lucky if and only if the method or process that produced it produced a true belief but produces false belief in close possible worlds.

Now, it is natural to interpret the notion of ‘similar circumstances’ occurring in our definition of local modal reliability in terms of close possible worlds. After all, close possible worlds are defined as worlds that differ little from the actual world. Such an interpretation of reliabilist justification fits well with Goldman’s claims regarding the modal profile of strong justification provided above, as well as with his treatment of BIV’s. Envatted subjects lack reliably formed beliefs because in worlds close to their actual world, their methods produce false beliefs too often. We will thus continue under the assumption that the notions of ‘close possible worlds’ and ‘similar situations’, as they occur in the definitions of veritic luck and local modal reliability, share their extension.

Admittedly, it is unclear how ‘wide’ the class of worlds where the agent forms a false belief in the same way as she formed her true belief in the actual world must be for a belief to count as veritically lucky. Footnote 13 But similarly, it is unclear what counts as a similar situation, on a local modal reliabilist conception of justification.

To circumvent this worry, I will assume that reliability and veritic luck are both graded notions. By this I mean that our beliefs can be more or less reliable than other beliefs, without it being clear that there is a sharp cut-off point between reliable and unreliable beliefs. The same holds for veritic luck: it is intuitively plausible that there is a continuum of veritic luck, where beliefs can be more, or less veritically lucky without there being a precise cut-off point where a veritically lucky belief becomes a non-veritically lucky one.

If this is true, then it follows that the higher the local modal reliability of a method is, the lower the degree of veritic luck will be that attaches to the beliefs produced by this method. In this sense, a local modal reliability condition behaves as an anti-veritic luck condition on justification. The more (locally modally) reliable your method, the less subject your beliefs are to veritic luck. In the extreme case, complete local modal reliability entails complete absence of veritic luck (in this case, there are no nearby possible worlds where one’s method produces a false belief).

A final point worth emphasizing in this section is that while RELIABILISM takes reliability to be both necessary and sufficient for justification, I will commit myself only to its necessity (that is why JUSTIFICATION does not feature a biconditional). There are several reasons for this, some will be outlined in the next section, and some in Sect. 6 . But perhaps the most important point presently is that I want to show as clearly as possible what is required to evade Gettier cases, and an anti-veritic luck condition on justification suffices for this purpose. Perhaps other conditions on justification are necessary, perhaps not. We will leave this question for another time.

Let us briefly recap. I have presented in this section a local modal interpretation of RELIABILISM supported by the writings of Alvin Goldman, and argues that it excludes veritic luck. This means that there is at least one prominent and plausible account of justification in the literature that satisfies JUSTIFICATION. I do not claim the interpretation presented in this section is the only possible interpretation of RELIABILISM, nor that it is Goldman’s own interpretation, nor that RELIABILISM is the only plausible account that satisfies JUSITIFICATION. My aim in this paper is only to establish that there is a plausible interpretation of justification that allows for an anti-luck defense of the tripartite analysis of knowledge, not that this defense is possible for all accounts of justification. In the next section I will provide further support for JUSTIFICATION by defending it against objections.

4 Lotteries, Evil Demons and Other Objections

While I have argued in the previous section that there is at least one prominent and plausible account that satisfies JUSTIFICATION, such an condition on justification is not widely endorsed in the literature. In this section I will review and respond to some possible objections.

First, I suspect some will find an anti-veritic luck condition too strong on the basis of how the account handles lottery cases. Instead, a probabilistic interpretation of RELIABILISM may be preferrable. In lottery cases, purely on the basis of the long odds involved, you form the (true) belief that the lottery ticket you just bought will lose. Forming your belief in this way will result in error in nearby worlds, since any of the tickets, including yours, could easily be drawn. If this much is admitted, then your belief is subject to at least some veritic luck, and our account seems to rule it as unjustified. This may strike some as counterintuitive. After all, the probability that your ticket is drawn is extremely small, given a large enough lottery. Thus, on this basis, one may prefer a probabilistic conception of RELIABILISM, where your belief is produced reliably just in case the probability of forming a false belief is small enough. In lottery cases, such a condition would be satisfied, which would allow proponents of such a reliabilism to say that lottery beliefs are justified.

In response, I would like to say the following things. First, it is not as clear cut as it may initially seem that lottery beliefs are justified. For example, some authors have argued for a knowledge norm on justification, and since it is universally accepted that we cannot know that our ticket will win on the basis of the odds alone, these views entail that lottery beliefs are not justified (Sutton 2005 ). Others have adduced other externalist conditions on justification that seem to rule out lottery beliefs from counting as justified (Littlejohn 2014 ; Smith forthcoming, 2016 ). In denying justification to lottery beliefs, I would not be alone.

Of course, it is better to provide a principled reason for denying justification in lottery cases. Our account provides such a reason: lottery beliefs are produced by a method that could have easily produced a false belief, and such methods fail to provide justification. This requires that the notion of easy possibility is given a modal characterization, but such interpretations have been fruitfully applied in philosophy at least since Lewis’ analysis of counterfactuals (Lewis 1973 ).

If one is not convinced, our verdict can be made more palatable by noting again that justification is a matter of degree. While JUSTIFICATION entails that lottery beliefs are not completely justified, since there are some nearby possibilities for error, our account is compatible with the idea that such beliefs still receive a relatively high degree of justification, since there are only a few such nearby error-possibilities. The only thing entailed by JUSTIFICATION is that lottery beliefs are not completely justified, but this same verdict must be reached by a probabilistic reliabilist. I conclude that lottery cases do not pose a serious threat to our account. Footnote 14

Let us move on to the next set of objections, both derived from Chris Kelp ( 2017 ). Kelp provides an alternative competence-based version of RELIABILISM, where (roughly) a belief is justified if and only if it is formed by an ability to form true beliefs. By providing both necessary and sufficient conditions on justification, Kelp’s account of justification is more ambitious than the present view, which commits itself to a necessary condition only.

In his paper, Kelp discusses two problems that may threaten JUSTIFICATION. Footnote 15 The first concerns new evil demon cases. Accounts like ours deny justification in such cases, since they feature beliefs that, if true at all, are subject to substantial degrees of veritic luck. Kelp maintains our verdict in these cases is implausible. In response, we have already argued against normic accounts of reliabilism that there are reasons to suppose victims in such deception cases lack justified beliefs, so I am prepared to bite this bullet. Moreover, Kelp’s own account of justification falls prey to a generalized version of the New Evil Demon case. Let us see why. Kelp evades standard new evil demon cases because according to Kelp, such cases involve conditions C “highly unsuitable for your ability to form true beliefs about the time in the sense that using W [your way of forming beliefs] in C does not dispose you to form true beliefs” (Kelp 2017 , p. 19). In standard new evil demon cases, however, W is grounded in normal conditions C’ (say, regular conditions as we take them to be on earth), in which exercising W does lead to true belief. So even in the demon case, you still form your beliefs by exercising an ability to form true beliefs, and so it seems that Kelp can accommodate the intuition that victims of radical deception are justified in their beliefs.

The case may be generalized, however, such that you are radically deceived since you were born. In such a case, your ability cannot be grounded in circumstances where you are disposed to form true beliefs (because you have never been able to form true beliefs about your environment). In this case, Kelp would have to agree that the relevant beliefs are unjustified. This puts our accounts in the same boat in this respect. To the extent that BIV’s and evil demon scenario’s count against our account, our generalized scenario should count against Kelp’s account as well. As said, however, I think the best way to respond to such scenarios is to bite the bullet. Whether our belief-forming methods provide us with justified beliefs depends on whether they are reliable guides to truth, and our present ways of forming our beliefs fail this criterion in radical deception cases.

The last objection I want to discuss concerns the kind of reliabilism I used in the previous section to support JUSTIFICATION. Kelp objects to standard process-reliabilist theories of justification that their measure of reliability depends on truth-falsity ratios at worlds. An account based on competences is better, according to Kelp, because competences are defined relative to conditions (you may competently play the piano, but not underwater). Kelp provides an example where people are generally unable to tell chantarelles from jack-of-lanterns, a very similar looking mushroom. Since chantarelles are edible but jack-of-lanterns are not, people cannot reliably tell whether a mushroom with the relevant appearance is edible, so their beliefs about this will not be justified on standard reliabilist accounts. Now imagine a secluded island where there are only chantarelles around. In this case, Kelp argues, we want to say that the beliefs of people living there about the edibility of these mushrooms are justified. His account predicts that they are, since in so believing they exercise an ability to believe truly. Reliabilism does not seem to deliver this verdict, because even if in their local context the beliefs are reliable, the kind of reliability adduced by standard process-reliabilism is defined over the whole world, which means, given the above, that their method is unreliable.

I want to grant Kelp the point against the standard kind of process-reliabilism that he discusses. But as we have made clear above, the general reliabilist framework is flexible enough to accommodate other measures of reliability than the one discussed by Kelp. In particular, we have been working with a local modal conception of reliability, which concerns reliability in cases similar to the actual case. Take any instance of a belief about the edibility of one of the chantarelles formed by someone living on the island described above. Does this way of forming their beliefs produce error in close possible worlds? Assuming that the person never leaves the island, it seems hard to deny that their method is locally modally reliable; quite a lot would have to change for this way of forming their beliefs to produce false belief here. Of course, that will change if one introduces jack-of-lanterns into the case, but the more of those we stipulate there to be on the island, the less strong our inclination to attribute justification, just as local modal reliabilism predicts.

All in all, our defense of JUSTIFICATION stands up to the challenges discussed above. Lottery beliefs may be justified to a high degree but are not completely justified. Beliefs of radically deceived agents do not seem to be justified at all. The final objection discussed emphasizes the plausibility of the local modal reliabilism used in the previous section to support JUSTIFICATION. The point of all this is to support the tripartite analysis of knowledge. In this next section, we compare our strategy to some recent alternatives.

5 Similar Strategies

I have argued that we can save the traditional analysis of knowledge against Gettier’s famous counterexamples if we properly understand what is required for justification. In different ways, Adrian Haddock and Mark Schoeder have argued for similar points (Haddock 2010 ; Schroeder 2015b ). Footnote 16 In this section, I will compare my account to theirs and provide some reasons for preferring the present one.

Let us address these accounts in alphabetical order. According to Adrian Haddock, knowledge is justified true belief where the justification condition is factive (one cannot justifiably believe that p when p is false) and requires moreover that the fact that provides justification is known by the subject. Haddock restricts his discussion to the case of visual knowledge, in which case, he argues, the fact that provides justification is ‘that one sees that p ’. Since both knowledge and seeing are factive states, it is impossible to be justified in this sense without it being the case that p. Footnote 17

We need not delve into the details of Haddocks account to note two main differences between it and the account presented in this paper. First, I do not consider justification to be a factive state in general. While complete justification may require the absence of false belief in nearby worlds, including our actual one, lesser degrees of justification do not, and are compatible with some false beliefs in nearby worlds, including our own. So, we can believe with a high degree of justification, on our present account, without it being the case that our belief is true. Secondly, I do not require the kind of second-order knowledge that Haddock requires for a belief to be justified. I suspect such a requirement is too strong, lest children, animals, and even probably most adult humans lack much of the knowledge we think they have. Rarely do we form beliefs about what justifies our beliefs, and when we do, such beliefs may simply be wrong, as the literature on cognitive bias makes painfully clear. Yet, as long as the methods we use to form the relevant beliefs are reliable enough, in our specific sense of local modal reliability, they may on our account amount to knowledge nonetheless. On our account knowing things about the world is a matter of having proper epistemic access to that world, and not of having proper second-order beliefs about the kind of access we enjoy.

Schroeder defines knowledge as belief for sufficient subjective and objective reason (Schroeder 2015b ). We will again focus on the case of visual knowledge. In cases of normal perception, you look at an object (say a dog) and form the belief that there is a dog over yonder. In such cases, according to Schroeder, your evidence is that you see that there is a dog over yonder . If you properly base your belief on this reason, it will count as subjectively sufficient (the fact that seeing is a factive state rationalizes your belief that there is a dog over yonder). If it is also true that you see that there is a dog over yonder (which for Schroeder means that there is no deception going on), then you also believe for objectively sufficient reason, and your belief may then amount to knowledge.

Schroeder is explicit in saying that doxastic justification for him requires believing for sufficient subjective reason only. This entails, among other things, that subjects’ beliefs in fake barn cases are doxastically justified on Schroeder’s account. Regarding a subject located in Fake Barn country, Schroeder says:

[S]he knows just in case the reasons for which she believes are both objectively and subjectively sufficient. And according to my take on the Kantian account [Schroeder’s account], her belief is doxastically rational just in case her reasons are subjectively sufficient. So given that the agent in the fake barn case believes rationally, the Kantian Account can deny that she knows only if it turns out that her reasons are not objectively sufficient. (Schroeder 2015a , p. 377)

Schroeder’s analysis of such cases thus seems to be one of doxastic justification but failure of knowledge because the subject’s subjectively sufficient reason is not also objectively sufficient. As an attempt to save the tripartite analysis, this strategy fails: we have here a case of doxastically justified true belief that nevertheless fails to amount to knowledge. The account also clearly conflicts with our present proposal, since on our account subjects in fake barn country do not know because they are not justified. In such cases, one’s method may all to easily produce false belief, such as when one is looking at a fake barn, and so one is not justified to believe there is a barn over yonder even if one is looking at the one real example.

Fake barn cases are controversial, but I think intuitions to the effect that fake-barn beliefs are justified can be explained away by noting that the same way of forming our beliefs about barns in the distance is presumably, in most of the contexts where we find ourselves, a locally modally reliable method. We don’t usually go wrong by using this method, we assume. And so, we conclude that using the method provides justification tout court . However, the point of requiring local modal reliability for justification is that it is plausible that whether a belief-forming method provides justification may differ across contexts. A method fit for forming true beliefs in one environment may not be so helpful in others. And in fake barn cases, going by eyesight errs too easily for that method to provide justification.

Thus, the approaches of Haddock and Schroeder are substantially different from the present one, which, I have argued, is to be preferred.

6 Further Implications

So far, I have argued that Gettier cases necessarily involve veritic luck, and that a local modal interpretation of RELIABILISM entails that justified beliefs cannot be veritically lucky. Together, these claims entail that no Gettier case can involve justified beliefs, and thus, that they do not provide counterexamples to the tripartite account of knowledge. Footnote 18 I have defended the account against objections and alternative analyses of knowledge. In this section, I discuss some implications of the present anti-luck approach to justification.

First, Linda Zagzebski has famously argued that Gettier cases are inescapable, in the sense that no non-factive account of justification immune to Gettier cases can be formulated (Zagzebski 1994 ). Since she explicitly discusses reliabilist conditions on justification, her findings may seem conflict with our claim that local modal reliabilism evades such cases. This impression would be incorrect, however, as Zagzebski is working with a probabilistic version of reliabilism, not a local modal one. Since I acknowledge that probabilistic versions of reliabilism will not suffice to rule out veritic luck, Zagzebski’s claim that reliabilism does not rule out veritic luck, properly understood, is compatible with what is argued here.

Zagzebski, however, further argues that no non - factive account of justification (where a factive account of justification is an account that entails justified beliefs are true) is going to be immune to Gettier cases. Footnote 19 As I have argued above, our general account of justification is non-factive. Justification comes in degrees. One’s belief is completely justified if there are no nearby possible worlds where one forms a false belief. Since the actual world counts as near to itself, it is not possible to be completely justified when one believes falsely. So, complete justification is factive on the present picture. But one may be justified to a lesser degree. In this case, the higher the proportion of nearby possible worlds where one forms a false belief, the lower one’s degree of justification. Since lower degrees of allow for false belief in nearby worlds, including the actual world, our general account of justification is non-factive.

It is a further question whether degrees of justification lower than complete justification suffice to rule out knowledge-undermining luck, and thus, in effect, whether knowledge requires complete justification on our account. I am inclined to think that knowledge may be compatible with minute amounts of veritic luck, given our frequent knowledge attributions. Officially, however, I will leave this as an open question. Knowledge may require complete justification (in which case the truth condition in the tripartite analysis is superfluous), or it may only require a lesser degree of justification (in which case the truth condition is required, and in which case our account provides a counterexample to Zagzebski’s claim). Footnote 20 Perhaps, as some have argued, the standards for knowledge depend on context, such that in some contexts, stronger justification is required than in others (Stanley 2005 ). Full discussion of this point will have to wait for another time; our account is flexible enough to handle any of the potential outcomes.

Let us return to our main line of argument. In this paper, I argued that there is a plausible account of justification where Gettier cases do not undermine the claim that knowledge is justified true belief. Why then, do so many epistemologists consider the tripartite analysis refuted?

The answer seems to be that before Gettier, justification is generally given an internalist gloss. Footnote 21 Because such accounts tend to be compatible with justified beliefs that are produced by methods that could very easily have produced false belief (BIV-beliefs, demon beliefs, etc.), such accounts will not eliminate veritic luck. Footnote 22 It is for this reason that Ted Poston, for example, writes: “[s]tandard Gettier cases show that one can have internally adequate justification without knowledge” ( 2016 , my emphasis). It is because our anti-luck condition is an externalist condition that it evades Gettier-cases.

Interestingly, internalist justification is incompatible with a different kind of luck:

REFLECTIVE LUCK S’s belief that p is reflectively lucky if and only if, given the information reflectively accessible to S , it is a matter of luck that the method S used to form her belief that p produced a true belief.

Note the parallels between veritic and reflective luck. Whereas veritic luck requires the belief to be true but produced by a method that could have easily produced false belief instead, the notion of reflective luck requires this same thing to be the case, but then judged from one’s reflective perspective. Footnote 23 Some examples of reflectively lucky beliefs include beliefs formed on the basis of simple guessing and the beliefs of Brandom’s famous chicken-sexers, or Bonjour’s equally famous clairvoyant (BonJour 1980 ; Brandom 1998 ). It is important to note that beliefs can be reflectively lucky without being veritically lucky (as is the case in the latter two examples mentioned above). Even if the chicken-sexer from her own perspective cannot explain why she reliably forms true belief, her method still is locally modally reliable. Similarly, beliefs can also be veritically lucky without being reflectively lucky, as when things look as if one’s method is a (locally modally) reliable one, whereas in fact it is not.

With the distinction between reflective and veritic luck in hand, it is possible to draw an alternative lesson from Gettier. The primary target of internalist concepts of justification is the elimination of reflective, not veritic luck. What Gettier showed us, is that there is another kind of luck that prevents knowledge: veritic luck. Since Gettier’s paper predates the careful distinctions of anti-luck epistemology, this point remains entirely implicit. Footnote 24

Still, I submit this is the main lesson from Gettier. It explains why Gettier cases are seen to refute the tripartite analysis of knowledge: because traditional accounts of justification aim to eliminate reflective but not veritic luck, the conditions laid down by these accounts can be satisfied even in the presence of veritic luck, which opens the door to Gettier cases.

The main lesson from Gettier is not that knowledge is incompatible with luck simpliciter, but specifically that knowledge is incompatible with veritic luck. A next question is then what this means for the analysis of knowledge. The overwhelming majority opinion is that Gettier refuted the classical, tripartite account of knowledge. But our present findings open up the possibility for a different interpretation. As I have been arguing in this paper, a plausible reading of reliabilist justification requires the elimination of veritic luck. On this account, Gettier cases lose their teeth. Footnote 25

7 Conclusion

Let us conclude. In this paper I have argued that by focussing on the relation between epistemic justification and luck, we can defend the traditional analysis of knowledge as justified, true, belief. Gettier cases are usually seen to refute any such attempt, but we have seen that all Gettier cases involve veritic luck, and that a plausible version of reliabilism about epistemic justification eliminates veritic luck. If this is so, then no belief in Gettier cases is epistemically justified, properly understood. That means that Gettier cases lose their teeth, and we can consistently maintain the claim that knowledge is justified true belief even in the light of any failure to know in Gettier cases.

Indeed, the claim that knowledge is not justified true belief is one of the few philosophical claims David Lewis took to be established conclusively: “Philosophical theories are never refuted conclusively. (Or hardly ever. Gödel and Gettier may have done it)” (Lewis 1983 , p. x).

In other work, I investigate in some detail the nature of veritic luck (de Grefte 2018 ). Here, I will rest content with providing a brief overview of the main conclusions of that investigation.

In recent work, Pritchard drops such a significance condition on luck (Pritchard 2014 ). See (de Grefte 2019 ) for discussion.

The definition of veritic luck that I am working with in this paper is different from those proposed by Pritchard (Pritchard 2005 , 2014 ) and Engel ( 1992 ). Reasons for my alternative formation are given in full in (de Grefte 2018 ). Briefly put, the difference is that for Pritchard, in order to be veritically lucky, a belief must be produced by a method that easily produces that very same belief , but it would be false. The reason we opt for the present requirement is Pritchard’s formulation renders beliefs in necessary truths necessarily non-lucky. For an objection along these lines see (Hales 2016 ). For a similar modification of Pritchard’s account, see (Goldberg 2015 , p. 274).

Here I assume that a guess whether p or not-p can easily result in either the belief that p or the belief that not-p.

The first of these assumptions is defended in (Whittington 2016 ). The second assumption is defended in (Pritchard 2005 , Chapter 6).

As is well-known, it is difficult to specify adequate criteria for the individuation of methods of belief-formation (e.g. Conee and Feldman 1998 ). I believe this problem, known as the ‘generality-problem’ is an issue for any adequate theory of justification, and I will not attempt to solve it in this paper. Instead, I rely on an intuitive understanding of the methods involved in my examples.

A non-factive condition on belief is a condition such that satisfying the condition does not entail the truth of the belief. Accounts of justification that feature only non-factive conditions on justification are called fallibilist accounts of justification.

The claim that Gettier cases necessarily involve veritic luck is relatively uncontroversial (e.g. Engel 1992 , p. 70; Pritchard 2005 , p. 150). For some recent objections, see (Bernecker 2011 ; Hetherington 2011 , Chapter 3).

For more on the distinction, see (Kornblith 2017 ; Silva and Oliveira forthcoming; Turri 2010 ).

We will come back to the relation between luck and the internalism/externalism debate in Sect. 6 .

I provide a more brief argument for this claim in my (de Grefte 2018 ).

Pritchard does go into this issue when he talks about the related notion of safety (Pritchard 2005 , Sects. 6.2–6.4).

It is worthwhile to pause on the distinction between partial and complete justification. In this paper, I argue that the tripartite account of knowledge can be saved from Gettier-style counterexamples by positing an anti-luck condition on justification. As I have shown above, Gettier cases necessarily involve veritic luck. But luck comes in degrees, so our beliefs may be subject to more or less veritic luck, The degree of veritic luck present in Gettier cases, is assumed to be high enough to destroy knowledge. But it is a further question, one not often explicitly dealt with in the literature, whether any degree of veritic luck is incompatible with knowledge. Lottery cases may be marshalled in support of the view that knowledge requires the absence of even low degrees of veritic luck, since, while the nearest possible world where one forms a false belief on the basis of the same method is close (just a few different numbers have to come up), but the proportion of nearby worlds where one forms a false belief on the basis of employing the same methods is arbitrarily small. Some veritic luck is involved, but not very much, it seems. The widespread intuition that lottery propositions are not known provides some evidence that knowledge is incompatible with even very small degrees of veritic luck. For the larger project of this paper this issue can be left undecided. To save the tripartite analysis, we only need to assume that knowledge is incompatible with the degree of veritic luck present in Gettier cases, and then argue that justification is incompatible with the same degree of veritic luck. This is what I have aimed to do in Sect. 3 . It should be noted, however, that our account is flexible enough to accommodate the thought that knowledge requires the complete absence of veritic luck, but that I am not committed to an account of justification that eliminates veritic luck completely. This issue will come up again in Sect. 6 .

Kelp discusses two other problems: clairvoyant cases and the generality problem. I will set the generality problem aside here, since this is a problem not specific to the present account (Bishop 2010 ), and would in any case require much more discussion. Clairvoyant cases are irrelevant in the present discussion because they seem to contradict the sufficiency of reliability for justification, a claim not endorsed in this paper.

Schroeder does not intend to save the tripartite analysis, since his account of knowledge features a fourth condition on knowledge (that the relevant belief is supported by sufficient objective reason). However, since he clearly aims to provide an analysis of knowledge, it is still worthwhile to compare the account to ours.

Haddock’s account of justification is not the only factive account of justification. Views that equate justification with knowledge, such as Sutton’s ( 2005 ) account, will entail that justification is factive. Also, disjunctivist accounts of perceptual knowledge such as McDowell’s ( 2009 ) may entail that justification (at least conceived of as the warrant required for knowledge) is factive. It is not possible here to compare my account to all alternatives. The decision to focus on the accounts of Haddock and Schroeder is motivated by the fact that both of them seem to be concerned explicitly with the analysis of knowledge. Since this is also my project here, the comparison between these different strategies is especially relevant.

This defence of the tripartite account is indirect because it concerns the removal of one of the main arguments against the tripartite account.

Zagzebski’s claim is relatively easily refuted. Suppose one posits that the absence of veritic luck is both necessary and sufficient for justification. Such an account is non-factive and able to evade Gettier cases. The arguments for the latter part of this claim have been provided above. Further, such an account would not be factive because a belief is veritically lucky only if it is both true and produced by a method that could easily have produced a false belief. False beliefs fail the first conjunct and so, on this account, cannot be veritically lucky. So, an account that posits that the absence of veritic luck is both necessary and sufficient is non-factive and immune to Gettier cases.

More recently, Zagzebski seems to admit as much when she discusses the lesson to be drawn from Gettier (Zagzebski 2017 ). While she thinks anti-luck approaches like the one from Howard-Snyder, Howard-Snyder and Feit ( 2003 ) are immune to Gettier cases, she thinks such accounts are ‘uninteresting’ and ‘ad-hoc’. Since these issues are not our central concern here, we will set them aside.

For some examples, see the theories explicitly targeted by Gettier: those of Chisholm ( 1957 , p. 16) and Ayer ( 1956 , p. 34).

See my (de Grefte 2018 ).

The notion of reflective luck is derived from Duncan Pritchard’s seminal work on epistemic luck (Pritchard 2005 ). Note that our account differs slightly from Pritchard’s account, just like our account of veritic luck differs slightly from Pritchard’s version in the same way as our account of veritic luck in order to avoid necessarily true propositions to be immune from reflective luck.

Note that I am not saying here that Gettier intended his cases to be read in this way. I am merely speculating that this is the best way to make sense of the cases, and the lesson to be drawn from them.

One note in closing, however. In modifying their justification conditions, externalists usually propose conditions that do not require the elimination of reflective luck. But it is perfectly consistent to require that justification requires both the absence of veritic, and of reflective luck. Prima facie, such an account of justification would seem to satisfy important externalist as well as internalist intuitions about justification. This is a theoretical possibility that is often overlooked in the debate between internalists and externalists, perhaps because externalism is often formulated as the explicit denial of internalism. Ernest Sosa is among the few epistemologists that have long stressed the importance of both externalist and internalist justification, at least when the higher grades of knowledge are concerned ( 2009 , 2010 ). Duncan Pritchard notes the compatibility but remains uncommitted toward such a hybrid account of justification ( 2005 , Chapters 6, 7, 8). A hybrid approach also seems compatible with Goldman’s distinction between strong and weak justification (Goldman 1988 ).

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I would like to thank Alvin Goldman for helpful disccussion of this material, as well as the audience from the OZSW Conference 2019 in Amsterdam, and two anonymous referees for this journal.

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Is Justified True Belief Knowledge? Essay Questions

1. Construct a Gettier counterexample of your own to the claim that justified true belief is knowledge. Explain why it is a counterexample.

2. Explain why Gettier’s case satisfies Ayer’s definition of knowledge (in the previous reading) and why it provides a counterexample to the definition.

3. Do you find Gettier’s case compelling? Why or why not?

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“Is Justified True Belief Knowledge?” by Gettier Essay

The thesis of Gettier’s article “Is Justified, True Belief Knowledge?” is centralized around methods of substantiating knowledge. According to the author, knowing that something is true takes several dimensions.

A person’s claim to knowledge depends on several factors including what the individual knows is true, his/her belief, and his/her right to be convinced. According to Ayer, these three factors form the basis of knowledge and its underlying definition.

On the other hand, Gettier argues that justified belief knowledge is false because it does not incorporate the element of ‘sufficient’ truth. Consequently, justified belief knowledge cannot be used to ascertain that a particular person knows that a certain proposition is true.

In addition, the article reveals that the concepts of ‘the right to be sure that’ and ‘has adequate evidence for’ only work if the element of ‘justified true belief’ is not introduced in an analysis. Gettier’s argument in the article “Is Justified, True Belief Knowledge?” focuses on the premises of truth, justified knowledge, adequate knowledge, and the right to be sure about something.

According to Gettier, in order for someone to know certain information several conditions have to be met. The first important condition for knowing certain information is the truthfulness of the particular suggestion. For instance, for someone to know a proposition, believe in it, accept it, and be sure it is the truth, the ‘information’ itself has to be true.

Gettier refutes the premise of justifiable true belief using the arguments of two other scholars; Chisholm and Ayer. According to Chisholm, a person has to accept a proposal and have adequate evidence to prove it in order for the aforementioned proposal to be true.

On the other hand, Ayer argues that any proposal is initially true. Consequently, a person becomes sure that the proposal is true, and he/she has the right to believe that it is so. According to Gettier, Ayer and Chisholm’s arguments are only true if the concept of ‘justified true belief’ is not introduced into their assertions.

Gettier’s main protest against ‘justified true belief’ is the fact that a person can use it to believe falsehoods. This argument is valid because believing in a proposition chiefly depends on the truthfulness of a conviction. Consequently, ‘believing’ a falsehood cannot be equated to ‘knowing’ it.

For example, someone can belief that person X is honest because he/she is justified to believe this to be true. The person’s conviction does not qualify to be termed as knowledge, because the person’s justified belief does not amount to ‘true knowledge’. When the same person finds out that X is dishonest, the premise of ‘justified true knowledge’ will subsequently be nullified.

Gettier uses parallel situations to access the premise of justified true belief. This method is quite effective because it enables Gettier to explore every possible outcome of a scenario that involves justified true belief. The author also offers a step-by-step analysis of what constitutes knowledge.

For example, the article contains two case-examples that pose hypothetical knowledge scenarios. In both scenarios, the author is able to prove that justifiable true belief does not provide substantial grounds for knowledge. Another argument that the author dwells upon although it is not given prominence involves changes in knowledge.

The article clearly proposes that propositions that are subject to future changes cannot be considered to be true. In retrospect, the author’s argument against justified true belief is another way of proving that true knowledge does not change.

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There are cases where something is true, but someone believes in the truth of invalid reason. The definition of these cases and all problems involving an element of truth, but existence of belief for invalid reasons is called the Gettier problem (stanford.edu). The problems expose inconsistencies in the model for evaluating the justifications of knowledge to create belief as outlined by Plato. However, knowledge is a justified true belief. The concept of knowledge as a justified true belief can be traced to the Plato. Plato proposed that for someone to believe in something, there has to be some sort of justification. Therefore, the definition of Knowledge is a justified true belief (stanford.edu). The implication of the definition is that for one to accept a proposition as true, there has to be some level of acceptable justification for the proposition. For example, for one to believe that a proposition, P, is true, P must be true, the subject must believe that P is true and have a justification for the belief. Therefore, the knowledge is a function of a justification and a belief. However, according to the Getteir problems, it is possible to for P to be true even where the justifications are not valid. For example, Gettier used examples of a person who believed that something was true without true justification (stanford.edu). For example, the question of Jane, believing that Mary own a Ford may be true. It meets two conditions of knowledge as a true belief because the belief is true and Jane believes that it is true. However, Jane has an invalid reason for her belief. For example, the justification is relevant because of a coincidence. The illustration shows that the aspect of justification is not a necessary part of the definition because it is possible for the argument to be flawed. For example, the luck involved in the justification does not change the status of the truth because the fact that Mary own the car remains a valid truth that can be justified by any other means (stanford.edu). The implication of the Gettier problem is that the conditions proposed by Plato are necessary conditions but not necessarily sufficient. For example, for something to be true, the conditions are necessary in the definition of a problem. In addition, all logical people have a rationale for having a belief, even where the rationale is not valid (stanford.edu). For example, in matters of faith, most people believe in Supernatural beings without any sort of proof.

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Plato on Knowledge in the Theaetetus

This article introduces Plato’s dialogue the Theaetetus (section 1), and briefly summarises its plot (section 2). Two leading interpretations of the dialogue, the Unitarian and Revisionist readings, are contrasted in section 3. Sections 4 to 8 explain and discuss the main arguments of the chief divisions of the dialogue. Section 9 provides some afterthoughts about the dialogue as a whole.

1. Introduction

2. summary of the dialogue, 3. overall interpretations of the theaetetus, 4. the introduction to the dialogue: 142a–145e, 5. definition by examples: 146a–151d, 6.1 the definition of knowledge as perception: 151d–e, 6.2 the “cold wind” argument; and the theory of flux: 152a–160e, 6.3 the refutation of the thesis that knowledge is perception: 160e5–186e12, 6.4 the digression: 172c1–177b7, 6.5 last objection to protagoras: 177c6–179b5, 6.6 last objection to heracleitus: 179c1–183c2, 6.7 the final refutation of d1 : 183c4–187a8, 7.1 the puzzle of misidentification: 187e5–188c8, 7.2 second puzzle about false belief: “believing what is not”: 188c10–189b9, 7.3 third puzzle about false belief: allodoxia : 189b10–190e4, 7.4 fourth puzzle about false belief: the wax tablet: 190e5–196c5, 7.5 fifth puzzle about false belief: the aviary: 196d1–200d4, 7.6 the final refutation of d2 : 200d5–201c7, 8.1 the dream of socrates: 201d8–202d7, 8.2 critique of the dream theory: 202d8–206c2, 8.3 three attempts to understand logos : 206c2–210a9, 9. conclusion, other internet resources, related entries.

The Theaetetus, which probably dates from about 369 BC, is arguably Plato’s greatest work on epistemology. (Arguably, it is his greatest work on anything.) Plato (c.427–347 BC) has much to say about the nature of knowledge elsewhere. But only the Theaetetus offers a set-piece discussion of the question “What is knowledge?”

Like many other Platonic dialogues, the Theaetetus is dominated by question-and-answer exchanges, with Socrates as main questioner. His two respondents are Theaetetus, a brilliant young mathematician, and Theaetetus’ tutor Theodorus, who is rather less young (and rather less brilliant).

Also like other Platonic dialogues, the main discussion of the Theaetetus is set within a framing conversation (142a–143c) between Eucleides and Terpsion (cp. Phaedo 59c). This frame may be meant as a dedication of the work to the memory of the man Theaetetus. Sedley 2004 (6–8) has argued that it is meant to set some distance between Plato’s authorial voice and the various other voices (including Socrates’) that are heard in the dialogue. Alternatively, or also, it may be intended, like Symposium 172–3, to prompt questions about the reliability of knowledge based on testimony. (Cp. the law-court passage ( Theaetetus 201a–c), and Socrates’ dream ( Theaetetus 201c–202c).)

The Theaetetus ’ most important similarity to other Platonic dialogues is that it is aporetic —it is a dialogue that ends in an impasse . The Theaetetus reviews three definitions of knowledge in turn; plus, in a preliminary discussion, one would-be definition which, it is said, does not really count. Each of these proposals is rejected, and no alternative is explicitly offered. Thus we complete the dialogue without discovering what knowledge is. We discover only three things that knowledge is not ( Theaetetus 210c; cp. 183a5, 187a1).

This matters, given the place that the Theaetetus is normally assigned in the chronology of Plato’s writings. Most scholars agree that Plato’s first writings were the “Socratic” dialogues (as they are often called), which ask questions of the “What is…?” form and typically fail to find answers: “What is courage?” ( Laches ), “What is self-control?” ( Charmides ), “What is justice?” ( Alcibiades I ; Republic 1), “What is holiness?” ( Euthyphro ), “What is friendship?” ( Lysis ), “What is virtue?” ( Meno ), “What is nobility?” ( Hippias Major ). After some transitional works ( Protagoras, Gorgias, Cratylus, Euthydemus ) comes a series of dialogues in which Plato writes to a less tightly-defined format, not always focusing on a “What is…?” question, nor using the question-and-answer interrogative method that he himself depicts as strictly Socratic: the Phaedo , the Phaedrus , the Symposium, and the Republic . In these dialogues Plato shows a much greater willingness to put positive and ambitious metaphysical views in Socrates’ mouth, and to make Socrates the spokesman for what we call “Plato’s theory of Forms.”

After these, it is normally supposed that Plato’s next two works were the Parmenides and the Theaetetus , probably in that order. If so, and if we take as seriously as Plato seems to the important criticisms of the theory of Forms that are made in the Parmenides , then the significance of the Theaetetus ’s return to the aporetic method looks obvious. Apparently Plato has abandoned the certainties of his middle-period works, such as the theory of Forms, and returned to the almost-sceptical manner of the early dialogues. In the Theaetetus , the Forms that so dominated the Republic ’s discussions of epistemology are hardly mentioned at all. A good understanding of the dialogue must make sense of this fact.

At the gates of the city of Megara in 369 BC, Eucleides and Terpsion hear a slave read out Eucleides’ memoir of a philosophical discussion that took place in 399 BC, shortly before Socrates’ trial and execution (142a–143c). In this, the young Theaetetus is introduced to Socrates by his mathematics tutor, Theodorus. Socrates questions Theaetetus about the nature of expertise, and this leads him to pose the key question of the dialogue: “What is knowledge?” (143d–145e). Theaetetus’ first response ( D0 ) is to give examples of knowledge such as geometry, astronomy, harmony, arithmetic (146a–c). Socrates objects that, for any x , examples of x are neither necessary nor sufficient for a definition of x (146d–147e). Theaetetus admits this, and contrasts the ease with which he and his classmates define mathematical terms with his inability to define knowledge (147c–148e). Socrates offers to explain Theaetetus’ bewilderment about the question “What is knowledge?” by comparing himself with a midwife: Theaetetus, he suggests, is in discomfort because he is in intellectual labour (148e–151d).

Thus prompted, Theaetetus states his first acceptable definition, which is the proposal that

Socrates does not respond to this directly. Instead he claims that D1 entails two other theories (Protagoras’ and Heracleitus’), which he expounds (151e–160e) and then criticises (160e–183c). Socrates eventually presents no fewer than eleven arguments, not all of which seem seriously intended, against the Protagorean and Heracleitean views. If any of these arguments hit its target, then by modus tollens D1 is also false. A more direct argument against D1 is eventually given at 184–7.

In 187b4–8, Theaetetus proposes a second definition of knowledge:

D2 provokes Socrates to ask: how can there be any such thing as false belief? There follows a five-phase discussion which attempts to come up with an account of false belief. All five of these attempts fail, and that appears to be the end of the topic of false belief. Finally, at 200d–201c, Socrates returns to D2 itself. He dismisses D2 just by arguing that accidental true beliefs cannot be called knowledge , giving Athenian jurymen as an example of accidental true belief.

Theaetetus tries a third time. His final proposal is:

The ensuing discussion attempts to spell out what it might be like for D3 to be true, then makes three attempts to spell out what a logos is.

In 201d–202d, the famous passage known as The Dream of Socrates , a two-part ontology of elements and complexes is proposed. Parallel to this ontology runs a theory of explanation that claims that to explain, to offer a logos, is to analyse complexes into their elements, i.e., those parts which cannot be further analysed. Crucially, the Dream Theory says that knowledge of O is true belief about O plus an account of O ’s composition. If O is not composite, O cannot be known, but only “perceived” (202b6). When Socrates argues against the Dream Theory (202d8–206b11), it is this entailment that he focuses on.

Socrates then turns to consider, and reject, three attempts to spell out what a logos is—to give an account of “account.” The first attempt takes logos just to mean “speech” or “statement” (206c–e). The second account (206e4–208b12) of “ logos of O ” takes it as “enumeration of the elements of O .” The third and last proposal (208c1–210a9) is that to give the logos of O is to cite the sêmeion or diaphora of O , the “sign” or diagnostic feature wherein O differs from everything else.

All three attempts to give an account of “account” fail. The day’s discussion, and the dialogue, end in aporia. Socrates leaves to face his enemies in the courtroom.

The Theaetetus is a principal field of battle for one of the main disputes between Plato’s interpreters. This is the dispute between Unitarians and Revisionists .

Unitarians argue that Plato’s works display a unity of doctrine and a continuity of purpose throughout. Unitarians include Aristotle, Proclus, and all the ancient and mediaeval commentators; Bishop Berkeley; and in the modern era, Schleiermacher, Ast, Shorey, Diès, Ross, Cornford, and Cherniss.

Revisionists retort that Plato’s works are full of revisions, retractations, and changes of direction. Eminent Revisionists include Lutoslawski, Ryle, Robinson, Runciman, Owen, McDowell, Bostock, and many recent commentators.

Unitarianism is historically the dominant interpretive tradition. Revisionism, it appears, was not invented until the text-critical methods, such as stylometry, that were developed in early nineteenth-century German biblical studies were transferred to Plato.

In the twentieth century, a different brand of Revisionism has dominated English-speaking Platonic studies. This owes its impetus to a desire to read Plato as charitably as possible, and a belief that a charitable reading of Plato’s works will minimise their dependence on the theory of Forms. (Corollary: Unitarians are likelier than Revisionists to be sympathetic to the theory of Forms.)

Unitarianism could be the thesis that all of Plato’s work is, really, Socratic in method and inspiration, and that Plato should be credited with no view that is not endorsed in the early dialogues. (In some recent writers, Unitarianism is this thesis: see Penner and Rowe (2005).) But this is not the most usual form of Unitarianism, which is more likely to “read back” the concerns of the Phaedo and the Republic into the Socratic dialogues, than to “read forward” the studied agnosticism of the early works into these more ambitious later dialogues. Likewise, Revisionism could be evidenced by the obvious changes of outlook that occur, e.g., between the Charmides and the Phaedo , or again between the Protagoras and the Gorgias . But the main focus of the Revisionist/Unitarian debate has never been on these dialogues. The contrasts between the Charmides and the Phaedo , and the Protagoras and the Gorgias, tell us little about the question whether Plato ever abandoned the theory of Forms. And that has usually been the key dispute between Revisionists and Unitarians.

Hence the debate has typically focused on the contrast between the “the Middle Period dialogues” and “the Late dialogues.” Revisionists say that the Middle Period dialogues enounce positive doctrines, above all the theory of Forms, which the Late dialogues criticise, reject, or simply bypass. The main place where Revisionists (e.g., Ryle 1939) suppose that Plato criticises the theory of Forms is in the Parmenides (though some Revisionists find criticism of the theory of Forms in the Theaetetus and Sophist as well). The main places where Revisionists look to see Plato managing without the theory of Forms are the Theaetetus and Sophist .

Ryle’s Revisionism was soon supported by other Oxford Plato scholars such as Robinson 1950 and Runciman 1962 (28). Revisionism was also defended by G.E.L. Owen. More recently, McDowell 1976, Bostock 1988, and Burnyeat 1990 are three classic books on the Theaetetus of a decidedly Revisionist tendency. (McDowell shows a particularly marked reluctance to bring in the theory of Forms anywhere where he is not absolutely compelled to.)

Revisionists are committed by their overall stance to a number of more particular views . They are more or less bound to say that the late Plato takes the Parmenides’ critique of the theory of Forms to be cogent, or at least impressive; that the Sophist’ s theory of “the five greatest kinds” ( Sophist 254b–258e) is not a development of the theory of Forms; and that the Timaeus was written before the Parmenides, because of the Timaeus’ apparent defence of theses from the theory of Forms. Their line on the Theaetetus will be that its argument does not support the theory of Forms; that the Theaetetus is interesting precisely because it shows us how good at epistemology Plato is once he frees himself from his obsession with the Forms.

Some of these Revisionist claims look easier for Unitarians to dispute than others. For example, Plato does not think that the arguments of Parmenides 130b–135c actually disprove the theory of Forms. Rather, it is obviously Plato’s view that Parmenides’ arguments against the Forms can be refuted. See Parmenides 135a–d, where Plato explicitly says—using Parmenides as his mouthpiece—that these arguments will be refuted by anyone of adequate philosophical training. (Whether anyone “of adequate philosophical training” is available is, of course, another question.)

Another problem for the Revisionist concerns Owen 1965’s proposal, adopted by Bostock 1988, to redate the Timaeus to the Middle Period, thus escaping the conclusion that Plato still accepted the theory of Forms at the end of his philosophical career. The trouble with this is that it is not only the Timaeus that the Revisionist needs to redate. In quite a number of apparently Late dialogues, Plato seems sympathetic to the theory of Forms: see e.g., Philebus 61e and Laws 965c.

On the other hand, the Revisionist claim that the Theaetetus shows Plato doing more or less completely without the theory of Forms is very plausible. There are no explicit mentions of the Forms at all in the Theaetetus , except possibly (and even this much is disputed) in what many take to be the philosophical backwater of the Digression. The main argument of the dialogue seems to get along without even implicit appeal to the theory of Forms. In the Theaetetus , Revisionism seems to be on its strongest ground of all.

The usual Unitarian answer is that this silence is studied. In the Theaetetus, Unitarians suggest, Plato is showing what knowledge is not . His argument is designed to show that certain sorts of alternatives to Plato’s own account of knowledge must fail. Plato demonstrates this failure by the ‘maieutic’ method of developing those accounts until they fail. Thus the Theaetetus shows the impossibility of a successful account of knowledge that does not invoke the Forms.

The fault-line between Unitarians and Revisionists is the deepest fissure separating interpreters of the Theaetetus . It is not the only distinction among overall interpretations of the dialogue. It has also been suggested, both in the ancient and the modern eras, that the Theaetetus is a sceptical work; that the Theaetetus is a genuinely aporetic work; and that the Theaetetus is a disjointed work. However, there is no space to review these possibilities here. It is time to look more closely at the detail of the arguments that Plato gives in the distinct sections of the dialogue.

We should not miss the three philosophical theses that are explicitly advanced in the Introduction. They are offered without argument by Socrates, and agreed to without argument by Theaetetus, at 145d7–145e5:

The wise are wise sophiai (= by/ because of/ in respect of/ as a result of wisdom:145d11).
To learn is to become wiser about the topic you are learning about (145d8–9).
Wisdom ( sophia ) and knowledge ( epistêmê ) are the same thing (145e5).

All three theses might seem contentious today. (1) seems to allude to Phaedo 100e’s notorious thesis about the role of the Form of F -ness in any x ’s being F —that x is F “ by the Form of F -ness.” (2) looks contentious because it implies (3); and (3) brings me to a second question about 142a–145e (which is also an important question about the whole dialogue): What is the meaning of the Greek word that I am translating as “knowledge,” epistêmê ?

Much has been written about Plato’s words for knowledge. One important question raised by Runciman 1962 is the question whether Plato was aware of the commonplace modern distinction between knowing that, knowing how, and knowing what (or whom). Nothing is more natural for modern philosophers than to contrast knowledge of objects (knowledge by acquaintance or objectual knowledge; French connaître ) with knowledge of how to do things (technique knowledge), and with knowledge of propositions or facts (propositional knowledge; French savoir ). Runciman doubts that Plato is aware of this threefold distinction (1962, 17): “At the time of writing the Theaetetus Plato had made no clear distinction [between] knowing that, knowing how, and knowing by acquaintance.”

Against this, Plato’s word for knowing how is surely tekhnê , from which we get the English word “technique.” Plato obviously thinks tekhnê incidental to a serious discussion of epistêmê . This is part of the point of the argument against definition by examples that begins at 146d (cp. 177c–179b).

As for the difference between knowing that and knowledge by acquaintance: the Theaetetus does mix passages that discuss the one sort of knowledge with passages that discuss the other. This does not imply that Plato was unaware of the difference. Perhaps he wants to discuss theories of knowledge that find deep conceptual connections between the two sorts of knowledge.

A grammatical point is relevant here. The objectual “I know Socrates” in classical Greek is oida (or gignôskô ) ton Sôkratên ; the propositional “I know Socrates is wise” is oida (or gignôskô ) ton Sôkratên sophon onta , literally “I know Socrates being wise” or, colloquially, just oida ton Sôkratên sophon , literally “I know Socrates wise”. Thus the Greek idiom can readily treat the object of propositional knowledge, which in English would most naturally be a that-clause, as a thing considered as having a quality . We might almost say that Greek treats what is known in propositional knowledge as just one special case of what is known in objectual knowledge. This suggests that the ancient Greeks naturally saw propositional and objectual knowledge as more closely related than we do (though not necessarily as indistinguishable). If so, Plato may have felt able to offer a single treatment for the two kinds of knowledge without thereby confusing them. The point will be relevant to the whole of the Theaetetus .

At 145d Socrates states the “one little question that puzzles” him: “What is knowledge?” Theaetetus’ first response ( D0 ) is to offer examples of knowledge (146c). Socrates rejects this response, arguing that, for any x , examples of x are neither necessary nor sufficient for a definition of x . They are not necessary, because they are irrelevant (146e). They are not sufficient, because they presuppose the understanding that a definition is meant to provide (147a–b). Moreover (147c), a definition could be briefly stated, whereas talking about examples is “an interminable diversion” ( aperanton hodon ).

Does Socrates produce good arguments against definition by examples? Many philosophers think not (McDowell 1976 (115), Geach 1966, Santas 1972, Burnyeat 1977). They often argue this by appealing to the authority of Wittgenstein, who famously complains ( The Blue and Brown Books , 20) that “When Socrates asks the question, ‘What is knowledge?’, he does not regard it even as a preliminary answer to enumerate cases of knowledge.” For arguments against this modern consensus, see Chappell 2005 (36–37).

Some commentators have taken Socrates’ critique of definition by examples to be an implicit critique of the Republic ’s procedure of distinguishing knowledge, belief, and ignorance by distinguishing their objects. The suggestion was first made by Ryle 1990 (23), who points out that “Socrates makes it clear that what he wants discussed is not a list of things that people know,” “but an elucidation of the concept of knowledge.” Ryle suggests that “Attention to this simple point might have saved Cornford from saying that the implicit conclusion of the dialogue is that ‘true knowledge has for its objects things of a different order’.” Ryle thinks it “silly” to suggest that knowledge can be defined merely by specifying its objects.

However, 145e–147c cannot be read as a critique of the Republic ’s procedure of distinguishing knowledge from belief by their objects. 145e–147c is not against defining knowledge by examples of objects of knowledge; it is against defining knowledge by examples of kinds of knowledge. (See e.g., 146e7, “We weren’t wanting to make a list of kinds of knowledge.”) This is a different matter.

Why, anyway, would the Platonist of the Republic think that examples of the objects of knowledge are enough for a definition of knowledge? He is surely the last person to think that. The person who will think this is the empiricist, who thinks that we acquire all our concepts by exposure to examples of their application: Locke, Essay II.1, Aristotle, Posterior Analytics 100a4–9. For the Platonist, definition by examples is never even possible; for the empiricist, definition by examples is the natural method in every case. This suggests that empiricism is a principal target of the argument of the Theaetetus . More about this in sections 6–8.

Theaetetus is puzzled by his own inability to answer Socrates’ request for a definition of knowledge, and contrasts it with the ease with which he can provide mathematical definitions. He gives an example of a mathematical definition; scholars are divided about the aptness of the parallel between this, and what would be needed for a definition of knowledge. Socrates’ response, when Theaetetus still protests his inability to define knowledge, is to compare himself to a midwife in a long and intricate analogy.

Many ancient Platonists read the midwife analogy, and more recently Cornford 1935 has read it, as alluding to the theory of recollection. But it is better not to import metaphysical assumptions into the text without good reason, and it is hard to see what the reason would be beyond a determination to insist that Plato always maintained the theory of recollection. With or without this speculation, the midwife passage does tell us something important about how the Theaetetus is going to proceed. In line with the classification that the ancient editors set at the front of the dialogue, it is going to be peirastikos , an experimental dialogue. It will try out a number of suggestions about the nature of knowledge. As in the aporetic dialogues, there is no guarantee that any of these suggestions will be successful (and every chance that none of them will be).

So read, the midwife passage can also tell us something important about the limitations of the Theaetetus’ inquiry. The limitations of the inquiry are the limitations of the main inquirers, and neither (the historical) Socrates nor Theaetetus was a card-carrying adherent of Plato’s theory of Forms. Perhaps the dialogue brings us only as far as the threshold of the theory of Forms precisely because, on Socratic principles, one can get no further. To get beyond where the Theaetetus leaves off, you have to be a Platonist. (For book-length developments of this reading of the Theaetetus, see Sedley 2004 and Chappell 2005.)

6. First Definition ( D1 ): “Knowledge is Perception”: 151e–187a

Between Stephanus pages 151 and 187, and leaving aside the Digression, 172–177 (section 6d), 31 pages of close and complex argument state, discuss, and eventually refute the first of Theaetetus’ three serious attempts at a definition of knowledge:

As before, there are two main alternative readings of 151–187: the Unitarian and the Revisionist. On the Unitarian reading, Plato’s purpose is to salvage as much as possible of the theories of Protagoras and Heracleitus (each respectfully described as ou phaulon : 151e8, 152d2). Plato’s strategy is to show that these theories have their own distinctive area of application, the perceptible or sensible world, within which they are true. However, the sensible world is not the whole world, and so these theories are not the whole truth. We get absurdities if we try to take them as unrestrictedly true. To avoid these absurdities it is necessary to posit the intelligible world (the world of the Forms) alongside the sensible world (the world of perception). When this is done, Platonism subsumes the theories of Protagoras and Heracleitus as partial truths. On this reading, the strategy of the discussion of D1 is to transcend Protagoras and Heracleitus: to explain their views by showing how they are, not the truth, but parts of a larger truth. In the process the discussion reveals logical pressures that may push us towards the two-worlds Platonism that many readers, e.g., Ross and Cornford, find in the Republic and Timaeus.

On the Revisionist reading, Plato’s purpose is to refute the theories of Protagoras and Heracleitus. He thinks that the absurdities those theories give rise to, come not from trying to take the theories as unrestrictedly true, but from trying to take them as true at all , even of the sensible world. Anyone who tries to take seriously the thesis that knowledge is perception has to adopt theories of knowledge and perception like Protagoras’ and Heracleitus’. But their theories are untenable. By modus tollens this shows that D1 itself is untenable. On this reading, the strategy of the discussion of D1 is to move us towards the view that sensible phenomena have to fall under the same general metaphysical theory as intelligible phenomena.

This outline of the two main alternatives for 151–187 shows how strategic and tactical issues of Plato interpretation interlock. For instance, the outline shows how important it is for an overall understanding of the Theaetetus to have a view on the following questions of detail (more about them later):

At 156a–157c, is Socrates just reporting, or also endorsing, a Heracleitean flux theory of perception?
What is the date of the Timaeus , which seems (28–29, 45b–46c, 49e) to present a very similar theory of perception to that found in Theaetetus 156–7?
What does Plato take to be the logical relations between the three positions under discussion in 151–184 ( D1 , Protagoras’ theory, and Heracleitus’ theory)? The closer he takes them to be, the more support that seems to give to the Revisionist view that the whole of 151–187 is one gigantic modus tollens . The more separate they are, the better for those versions of Unitarianism that suggest that Plato wants to pick and choose among the positions offered in 151–187.

So much for the overall structure of 151–187; now for the parts.

At 151d7–e3 Theaetetus proposes:

Socrates immediately equates D1 with Protagoras’s thesis that

and takes this, in turn, to entail the thesis:

Socrates then adds that, in its turn, PS entails Heracleitus’ view that “All is flux,” that there are no stably existing objects with stably enduring qualities .

The first of these deft exchanges struck the Anonymous Commentator as disingenuous: “Plato himself knew that Protagoras’ opinion about knowledge was not the same as Theaetetus’” (Anon, ad loc. ). Certainly it is easy to see counter-examples to the alleged entailment. Take, for instance, the thesis that knowledge is awareness (which is often the right way to translate aisthêsis ). Or take the thesis that to know is to perceive things as God, or the Ideal Observer, perceives them, and that we fail to know (or to perceive) just insofar as our opinions are other than God’s or the Ideal Observer’s. These theses are both versions of D1 . Neither version entails the claim that “man is the measure of all things” ( Hm )—nor the Protagorean view that lies behind that slogan.

So how, if at all, does D1 entail all the things that Socrates apparently makes it entail in 151–184? And does Plato think it has all these entailments? Evidently the answer to that depends on how we understand D1 . In particular, it depends on the meaning of the word aisthêsis , “perception,” in D1 . If the slogan “Knowledge is perception” equates knowledge with what ordinary speakers of classical Greek would have meant by aisthêsis , then D1 does not entail Protagoras’ and Heracleitus’ views. In the ordinary sense of aisthêsis , there are (as just pointed out) too many other possible ways of spelling out D1 for the move from D1 to Hm to be logically obligatory. But if the slogan “Knowledge is perception” equates knowledge with what Protagoras and Heracleitus meant by aisthêsis , D1 does entail Protagoras’ and Heracleitus’ views. Of course it does; for then D1 simply says that knowledge is just what Protagoras and Heracleitus say knowledge is.

At 152b1–152c8 Socrates begins his presentation of Protagoras’ view that things are to any human just as they appear to that human by taking the example of a wind which affects two people differently. Such cases, he says, support Protagoras’ analysis: “that the wind is cold to the one who feels cold , but not cold to the one who does not feel cold. ”

Some scholars (Cornford 1935, 33–4; Waterlow 1977) think that the point of the argument is that both “the wind in itself is cold” and “the wind in itself is not cold (but warm)” are true: “‘Warm’ and ‘cold’ are two properties which can co-exist in the same physical object. I perceive the one, you perceive the other.” The trouble with this suggestion is that much of the detail of the Protagorean/Heracleitean position in 151–184 seems to be generated by Protagoras’ desire to avoid contradiction. If Cornford thinks that Protagoras is not concerned to avoid contradicting himself, then he has a huge task of reinterpretation ahead of him.

Rather, perhaps, the point of the argument is this: Neither “The wind in itself is cold” nor “The wind in itself is warm” is true. If we had grounds for affirming either, we would have equally good grounds for affirming both; but the conjunction “The wind in itself is cold and the wind in itself is warm” is a contradiction. This contradiction, says Protagoras, obliges us to give up all talk about “the wind in itself,” and switch to relativised talk about the wind as it seems to me or to you, etc. (The same contradiction pushes the Plato of the Republic in the opposite direction: it leads him to place no further trust in any relativised talk, precisely because such talk cannot get us beyond such contradictions.)

So we have moved from D1 , to Hm , to PS . At 152c8–152e1 Socrates adds that, in its turn, PS entails Heracleitus’ view that “All is flux,” that there are no stably existing objects with stably enduring qualities. The reason given for this is the same thought as the one at the centre of the cold-wind argument: that everything to which any predicate can be applied, according to one perception, can also have the negation of that predicate applied to it, according to an opposite perception with equally good credentials.

After a passage (152e1–153d5) in which Socrates presents what seem to be deliberately bad arguments, eight of them, for Heracleitus’ flux thesis, Socrates notes three shocking theses which the flux theory implies:

Qualities have no independent existence in time and space (153d6–e1).
Qualities do not exist except in perceptions of them (153e3–154a8).
(The dice paradox:) changes in a thing’s qualities are not so much changes in that thing as in perceptions of that thing (154a9–155c6).

These shocking implications, Socrates says, give the phenomenal subjectivist his reason to reject the entire object/quality metaphysics, and to replace it with a metaphysics of flux.

In 155c–157c the flux theory is used to develop a Protagorean/Heracleitean account of perception, to replace accounts based on the object/property ontology of common sense. Socrates notes the subversive implications of the theory of flux for the meaningfulness and truth-aptness of most of our language as it stands. (He returns to this point at 183a–b.) The ontology of the flux theory distinguishes kinds of “process” ( kinêsis ), i.e., of flux, in two ways: as fast or slow, and as active or passive. Hence there are four such processes. On these the flux theory’s account of perception rests.

A rather similar theory of perception is given by Plato in Timaeus 45b–46c, 67c–68d. This fact has much exercised scholars, since it relates closely to the question whether Plato himself accepts the flux theory of perception (cp. Theaetetus 157c5). The question is important because it connects with the question of whether the Revisionist or Unitarian reading of 151–187 is right. (For more on this issue, see Cornford 1935 (49–50); Crombie 1963, II (21–22); Burnyeat 1990 (17–18); McDowell 1973 (139–140), Chappell 2005 (74–78).)

At 157c–160c Socrates states a first objection to the flux theory. This asks how the flux theorist is to distinguish false (deceptive) appearances such as dreams from the true (undeceptive) appearances of the waking world. The flux theorist’s answer is that such appearances should not be described as ‘true’ and ‘false’ appearances to the same person. Rather they should be described as different appearances to different people. According to the flux theorist, we have the same person if and only if we have the same combination of a perception and a perceiving (159c–d). So there is no need to call any appearances false . Thus we preserve the claim that all appearances are true—a claim which must be true if knowledge is perception in the sense that Socrates has taken that definition.

160b–d summarises the whole of 151–160. Socrates shows how the exploration of Theaetetus’ identification of knowledge with perception has led us to develop a whole battery of views: in particular, a Protagorean doctrine of the incorrigibility of perception, and a Heracleitean account of what perception is. Thus “perception has one of the two marks of knowledge, infallibility” (Cornford 1935, 58); “and, if we can accept Protagoras’ identification of what appears to me with what is, ignoring the addition ‘for me’ and the distinction between being and becoming, the case will be complete.”

160e marks the transition from the statement and exposition of the definition of knowledge as perception ( D1 ), to the presentation of criticism and refutation of that definition.

Scholars have divided about the overall purpose of 160e–186e. Mostly they have divided along the lines described in section 3, taking either a Revisionist or a Unitarian view of Part One of the Theaetetus .

Revisionists say that the target of the critique of 160e–186e is everything that has been said in support and development of D1 ever since 151. Unitarians argue that Plato’s criticism of D1 in 160e–186e is more selective. Obviously his aim is to refute D1 , the equation of knowledge with perception. But that does not oblige him to reject the account of perception that has been offered in support of D1 . And Plato does not reject this account: he accepts it.

Thus the Unitarian Cornford argues that Plato is not rejecting the Heracleitean flux theory of perception. He is rejecting only D1 ’s claim that knowledge is that sort of perception. It remains possible that perception is just as Heracleitus describes it. Likewise, Cornford suggests, the Protagorean doctrine that “man is the measure of all things” is true provided it is taken to mean only “all things that we perceive .”

If some form of Unitarianism is correct, an examination of 160–186 should show that Plato’s strategy in the critique of D1 highlights two distinctions:

A distinction between the claim that the objects of perception are in flux, and the claim that everything is in flux.
A distinction between bare sensory awareness, and judgement on the basis of such awareness.

One vital passage for distinction (1) is 181b–183b. If Unitarianism is right, this passage should be an attack on the Heracleitean thesis that everything is in flux, but not an attack on the Heracleitean thesis that the objects of perception are in flux. According to Unitarians, the thesis that the objects of perception are in flux is a Platonic thesis too. Readers should ask themselves whether this is the right way to read 181b –183b.

Distinction (2) seems to be explicitly stated at 179c. There also seems to be clear evidence of distinction (2) in the final argument against D1 , at 184–187. Distinction (2) is also at work, apparently, in the discussion of some of the nine objections addressed to the Protagorean theory. Some of these objections can plausibly be read as points about the unattractive consequences of failing to distinguish the Protagorean claim that bare sense-awareness is incorrigible (as the Unitarian Plato agrees) from the further Protagorean claim that judgements about sense-awareness are incorrigible (which the Unitarian Plato denies).

The criticism of D1 breaks down into twelve separate arguments, interrupted by the Digression (172c–177c: translated and discussed separately in section 6.4 below). There is no space here to comment in detail on every one of these arguments, some of which, as noted above, have often been thought frivolous or comically intended (cp. 152e1–153d5). Some brief notes on the earlier objections will show what the serious point of each might be.

The first objection to Protagoras (160e–161d) observes that if all perceptions are true, then there is no reason to think that animal perceptions are inferior to human ones: a situation which Socrates finds absurd.

If this objection is really concerned with perceptions strictly so called, then it obviously fails. Protagoras just accepts this supposedly absurd consequence; and apparently he is right to do so. If we consider animals and humans just as perceivers, there is no automatic reason to prefer human perceptions. Many animal perceptions are superior to human perceptions (dogs’ hearing, hawks’ eyesight, dolphins’ echolocatory ability, most mammals’ sense of smell, etc.), and the Greeks knew it, cf. Homer’s commonplace remarks about “far-sighted eagles”, or indeed Aristotle, in the Eudemian Ethics , 1231a5–6. The objection works much better rephrased as an objection about judgements about perceptions, rather than about perceptions strictly so called. Humans are no more and no less perceivers than pigs, baboons, or tadpoles. But they are different in their powers of judgement about perceptions.

This distinction between arguments against a Protagorean view about perception and a Protagorean view about judgement about perception is relevant to the second objection too (161d–162a). This objection (cp. Cratylus 386c) makes the point that Protagoras’ theory implies that no one is wiser than anyone else. Notably, the argument does not attack the idea that perception is infallible. Rather, it attacks the idea that the opinion or judgement that anyone forms on the basis of perception is infallible (161d3). (This is an important piece of support for Unitarianism: cp. distinction (2) above.)

A third objection to Protagoras’ thesis is very quickly stated in Socrates’ two rhetorical questions at 162c2–6. Since Protagoras’ thesis implies that all perceptions are true, it not only has the allegedly absurd consequence that animals’ perceptions are not inferior to humans. It also has the consequence that humans’ perceptions are not inferior to the gods’. This consequence too is now said to be absurd.

As with the first two objections, so here. If we consider divinities and humans just as perceivers, there is no automatic reason to prefer divine perceptions, and hence no absurdity. Plato may well want us to infer that the Greek gods are not different just in respect of being perceivers from humans. But they are different in their powers of judgement about perceptions.

The next four arguments (163a–168c) present counter-examples to the alleged equivalence of knowledge and perception. The fourth observes that, if perception = knowledge, then anyone who perceives an utterance in a given language should have knowledge of that utterance, i.e., understand it—which plainly doesn’t happen. The fifth raises a similar problem about memory and perception: remembering things is knowing them, but not perceiving them. The sixth (the “covered eye”) objection contrasts not perceiving an object (in one sensory modality) with not knowing it . If perception = knowledge, seeing an object with one eye and not seeing it with the other would appear to be a case of the contradictory state of both knowing it and not knowing it. The seventh points out that one can perceive dimly or faintly, clearly or unclearly, but that these adverbial distinctions do not apply to ways of knowing—as they must if knowing is perceiving.

In 165e4–168c5, Socrates sketches Protagoras’s response to these seven objections. Protagoras makes two main points. First, he can meet some of the objections by distinguishing types and occasions of perception. Second, teaching as he understands it is not a matter of getting the pupil to have true rather than false beliefs. Since there are no false beliefs, the change that a teacher can effect is not a change from false belief to true belief or knowledge. Rather, Protagoras’ model of teaching is a therapeutic model. What a good teacher does, according to him, is use arguments (or discourses: logoi ) as a good doctor uses drugs, to replace the state of the soul in which “bad things are and appear” with one in which “good things are and appear.” While all beliefs are true , not all beliefs are beneficial .

A difficulty for Protagoras’ position here is that, if all beliefs are true, then all beliefs about which beliefs are beneficial must be true. But surely, some beliefs about which beliefs are beneficial contradict other beliefs about which beliefs are beneficial; especially if some people are better than others at bringing about beneficial beliefs. (For example, no doubt Plato’s and Protagoras’ beliefs conflict at this point.) This means that Protagoras’ view entails a contradiction of the same sort as the next objection–the famous peritropê —seems to be meant to bring out.

The peritropê (“table-turning”) objection (171a–b) is this. Suppose I believe, as Protagoras does, that “All beliefs are true,” but also admit that “There is a belief that ‘Not all beliefs are true’.” If all beliefs are true, the belief that “Not all beliefs are true” must be true too. But if that belief is true, then by disquotation, not all beliefs are true. So I refute myself by contradicting myself; and the same holds for Protagoras.

The validity of the objection has been much disputed. Burnyeat, Denyer and Sedley all offer reconstructions of the objection that make it come out valid. McDowell and Bostock suggest that although the objection does not prove what it is meant to prove (self-contradiction), it does prove a different point (about self-defeat) which is equally worth making.

Socrates’ ninth objection presents Protagoras’ theory with a dilemma. If the theory is completely general in its application, then it must say that not only what counts as justice in cities, but also what benefits cities, is a relative matter. As Protagoras has already admitted (167a3), it is implausible to say that benefit is a relative notion. But the alternative, which Protagoras apparently prefers, is a conceptual divorce between the notions of justice and benefit, which restrict the application of Protagoras’ theory to the notion of justice. Socrates obviously finds this conceptual divorce unattractive, though he does not, directly, say why. Instead, he offers us the Digression.

An obvious question: what is the Digression for? One answer (defended in Chappell 2004, ad loc.) would be that it is a critique of the society that produces the conceptual divorce between justice and benefit that has just emerged. Socrates draws an extended parallel between two types of character, the philosophical man and the man of rhetoric, to show that it is better to be the philosophical type.

The Digression is “philosophically quite pointless,” according to Ryle 1966: 158. Less dismissively, McDowell 1976: 174 suggests that the Digression serves “a purpose which, in a modern book, might be served by footnotes or an appendix.” Similarly, Cornford 1935 (83) suggests that Plato aims to give the reader some references for anti-relativist arguments that he presents elsewhere: “To argue explicitly against it would perhaps take him too far from the original topic of perception. Instead, he inserts [the Digression], which contains allusions to such arguments in other works of his.”

Perhaps the Digression paints a picture of what it is like to live in accordance with the two different accounts of knowledge, the Protagorean and the Platonist, that Plato is comparing. Thus the Digression shows us what is ethically at stake in the often abstruse debates found elsewhere in the Theaetetus . Its point is that we can’t make a decision about what account of knowledge to accept without making all sorts of other decisions, not only about the technical, logical and metaphysical matters that are to the fore in the rest of the Theaetetus , but also about questions of deep ethical significance. So, for instance, it can hardly be an accident that, at 176c2, the difference between justice and injustice is said to be a difference between knowledge ( gnôsis ) and ignorance ( agnoia ).

Another common question about the Digression is: does it introduce or mention the Platonic Forms? Certainly the Digression uses phrases that are indisputably part of the Middle-Period language for the Forms. If Plato uses the language of the theory of Forms in a passage which is admitted on all sides to allude to the themes of the Republic , it strains credulity to imagine that Plato is not intentionally referring to the Forms in that passage.

On the other hand, as the Revisionist will point out, the Theaetetus does not seem to do much with the Forms that are thus allegedly introduced. But perhaps it would undermine the Unitarian reading of the Theaetetus if the Forms were present in the Digression in the role of paradigm objects of knowledge. For the Unitarian reading, at least on the version that strikes me as most plausible, says that the aim of the Theaetetus is to show that, in the end, we cannot construct a theory of knowledge without the Forms—a claim which is to be proved by trying and failing, three times, to do so. So if the Forms were there in the Digression, perhaps that would be a case of “giving the game away.”

After the Digression Socrates returns to criticising Protagoras’ relativism. His last objection is that there is no coherent way of applying Protagoras’ relativism to judgements about the future.

How might Protagoras counter this objection? Protagoras has already suggested that the past may now be no more than whatever I now remember it to have been (166b). Perhaps he can also suggest that the future is now no more than I now believe it will be. No prediction is ever proved wrong, just as no memory is ever inaccurate. All that happens is it seems to one self at one time that something will be true (or has been true), and seems to another self at another time that something different is true.

But these appeals to distinctions between Protagorean selves—future or past—do not help. Suppose we grant to Protagoras that, when I make a claim about how the future will be, this claim concerns how things will be for my future self . It is just irrelevant to add that my future self and I are different beings. Claims about the future still have a form that makes them refutable by someone’s future experience. If I predict on Monday that on Tuesday my head will hurt, that claim is falsified either if I have no headache on Tuesday, or if, on Tuesday, there is someone who is by convention picked out as my continuant whose head does not hurt.

Similarly with the past. Suppose I know on Tuesday that on Monday I predicted that on Tuesday my head would hurt. It is no help against the present objection for me to reflect, on Tuesday, that I am a different person now from who I was then. My Monday-self can only have meant either that his head would hurt on Tuesday, which was a false belief on his part if he no longer exists on Tuesday; or else that the Tuesday-self would have a sore head. But if the Tuesday-self has no sore head, then my Monday-self made a false prediction, and so must have had a false belief. Either way, the relativist does not escape the objection.

Moreover, this defence of Protagoras does not evade the following dilemma. Either what I mean by claiming (to take an example of Bostock’s) that “The wine will taste raw to me in five years’ time” is literally that. Or else what I mean is just “ It seems to me that the wine will taste raw to me in five years’ time.”

Suppose I mean the former assertion. If the wine turns out not to taste raw five years hence, Protagoras has no defence from the conclusion that I made a false prediction about how things would seem to me in five years. Or suppose I meant the latter assertion. Then I did not make a prediction , strictly speaking, at all; merely a remark about what presently seems to me. Either way, Protagoras loses.

Socrates argues that if Heracleitus’ doctrine of flux is true, then no assertion whatever can properly be made. Therefore (a) Heracleitus’ theory of flux no more helps to prove that knowledge is perception than that knowledge is not perception, and (b) Heracleiteans cannot coherently say anything at all, not even to state their own doctrine.

There are two variants of the argument. On the first of these variants, evident in 181c2–e10, Socrates distinguishes just two kinds of flux or process, namely qualitative alteration and spatial motion, and insists that the Heracleiteans are committed to saying that both are continual. On the second variant, evident perhaps at 182a1, 182e4–5, Socrates distinguishes indefinitely many kinds of flux or process, not just qualitative alteration and motion through space, and insists that the Heracleiteans are committed to saying that every kind of flux is continual.

Now the view that everything is always changing in every way might seem a rather foolish view to take about everyday objects. But, as 182a2–b8 shows, the present argument is not about everyday objects anyway. Plato does not apply his distinction between kinds of change to every sort of object whatever, including everyday objects. He applies it specifically to the objects (if that is the word) of Heracleitean metaphysics. These items are supposed by the Heracleitean to be the reality underlying all talk of everyday objects. It is at the level of these Heracleitean perceivings and perceivers that Plato’s argument against Heracleitus is pitched. And it is not obviously silly to suppose that Heracleitean perceivings and perceivers are constantly changing in every way.

The argument that Socrates presents on the Heracleiteans’ behalf infers from “Everything is always changing in every way” that “No description of anything is excluded.” How does this follow? McDowell 1976: 181–2 finds the missing link in the impossibility of identifications . We cannot (says McDowell) identify a moving sample of whiteness, or of seeing, any longer once it has changed into some other colour, or perception.

But this only excludes re identifications: presumably I can identify the moving whiteness or the moving seeing until it changes, even if this only gives me an instant in which to identify it. This point renders McDowell’s version, as it stands, an invalid argument. If it is on his account possible to identify the moving whiteness until it changes , then it is on his account possible to identify the moving whiteness. But if that is possible, then his argument contradicts itself: for it goes on to deny this possibility.

Some other accounts of the argument also commit this fallacy. Compare Sayre’s account (1969: 94): “If no statement, either affirmative or negative, can remain true for longer than the time taken in its utterance, then no statement can be treated as either true or false, and the cause of communicating with one’s fellow beings must be given up as hopeless.”

Sayre’s argument aims at the conclusion “No statement can be treated as either true or false.” But Sayre goes via the premiss “Any statement remains true no longer than the time taken in its utterance.” If there are statements which are true, even if they are not true for very long, it is not clear why these statements cannot be treated as true, at least in principle (and in practice too, given creatures with the right sensory equipment and sense of time).

McDowell’s and Sayre’s versions of the argument also face the following objection. It is obvious how, given flux, a present-tense claim like “Item X is present” can quickly cease to be true, because e.g., “Item Y is present” comes to replace it. But it isn’t obvious why flux should exclude the possibility of past-tense statements like “Item X flowed into item Y between t 1 and t 2 ,” or of tenseless statements like “Item X is present at t 1 , item Y is present at t 2 .” As Bostock 1988: 105–6 points out, “So long as we do have a language with stable meanings, and the ability to make temporal distinctions, there is no difficulty at all about describing an ever-changing world.”

“So long as” : to make the argument workable, we may suggest that its point is that the meanings of words are exempt from flux. If meanings are not in flux, and if we have access to those meanings, nothing stops us from identifying the whiteness at least until it flows away. But if meanings are in flux too, we will have the result that the argument against Heracleitus actually produces at 183a5: anything at all will count equally well as identifying or not identifying the whiteness. “Unless we recognise some class of knowable entities exempt from the Heracleitean flux and so capable of standing as the fixed meanings of words, no definition of knowledge can be any more true than its contradictory. Plato is determined to make us feel the need of his Forms without mentioning them” (Cornford 1935, 99).

Socrates completes his refutation of the thesis that knowledge is perception by bringing a twelfth and final objection, directed against D1 itself rather than its Protagorean or Heracleitean interpretations. This objection says that the mind makes use of a range of concepts which it could not have acquired, and which do not operate, through the senses: e.g., “existence,” “sameness,” “difference.” So there is a part of thought, and hence of knowledge, which has nothing to do with perception. Therefore knowledge is not perception.

Unitarians and Revisionists will read this last argument against D1 in line with their general orientations. Unitarians will suggest that Socrates’ range of concepts common to the senses is a list of Forms. They will point to the similarities between the image of the senses as soldiers in a wooden horse that Socrates offers at 184d1 ff., and the picture of a Heracleitean self, existing only in its awareness of particular perceptions, that he drew at 156–160.

Revisionists will retort that there are important differences between the Heracleitean self and the wooden-horse self, differences that show that Heracleiteanism is no longer in force in 184–187. They will insist that the view of perception in play in 184–187 is Plato’s own non-Heracleitean view of perception. Thus Burnyeat 1990: 55–56 argues that, since Heracleiteanism has been refuted by 184, “the organs and subjects dealt with [in the Wooden Horse passage] are the ordinary stable kind which continue in being from one moment to the next.” On the other hand, notice that Plato’s equivalent for Burnyeat’s “organs and subjects” is the single word aisthêseis (184d2). On its own, the word can mean either “senses” or “sensings”; but it seems significant that it was the word Plato used at 156b1 for one of the two sorts of Heracleitean “offspring.” Plato speaks of the aisthêseis concealed “as if within a Wooden Horse” as pollai tines (184d1), “indefinitely many.” But while there are indefinitely many Heracleitean sensings , there are not, of course, indefinitely many senses . Indeed even the claim that we have many senses ( pollai ), rather than several ( enioi , tines ), does not sound quite right, either in English or in Greek. This is perhaps why most translators, assuming that aisthêseis means “senses,” put “a number of senses” for pollai tines aisthêseis . Perhaps this is a mistake, and what aisthêseis means here is “Heracleitean sensings.” If so, this explains how the aisthêseis inside any given Wooden Horse can be pollai tines.

If the aisthêseis in the Wooden Horse are Heracleitean sensings , not ordinary, un-Heracleitean senses , this supports the Unitarian idea that 184–187 is contrasting Heracleitean perceiving of particulars with Platonic knowing of the Forms (or knowing of particulars via , and in terms of , the Forms).

Another piece of evidence pointing in the same direction is the similarity between Plato’s list of the “common notions” at Theaetetus 186a and closely contemporary lists that he gives of the Forms, such as the list of Forms ( likeness , multitude , rest and their opposites) given at Parmenides 129d, with ethical additions at Parmenides 130b. There are also the megista genê (“greatest kinds”) of Sophist 254b–258e ( being , sameness , otherness , rest and change ); though whether these genê are Forms is controversial.

7. Second Definition ( D2 ): “Knowledge is True Judgement”: 187b–201c

151–187 has considered and rejected the proposal that knowledge is perception. Sometimes in 151–187 “perception” seems to mean “immediate sensory awareness”; at other times it seems to mean “judgements made about immediate sensory awareness.” The proposal that “Knowledge is immediate sensory awareness” is rejected as incoherent: “Knowledge is not to be found in our bodily experiences, but in our reasonings about those experiences” (186d2). The proposal that “Knowledge is judgement about immediate sensory awareness” raises the question how judgements, or beliefs, can emerge from immediate sensory awareness. Answering this question is the main aim in 187–201.

Empiricists claim that sensation, which in itself has no cognitive content, is the source of all beliefs, which essentially have cognitive content—which are by their very nature candidates for truth or falsity. So unless we can explain how beliefs can be true or false, we cannot explain how there can be beliefs at all. Hence Plato’s interest in the question of false belief. What Plato wants to show in 187–201 is that there is no way for the empiricist to construct contentful belief from contentless sensory awareness alone. The corollary is, of course, that we need something else besides sensory awareness to explain belief. In modern terms, we need irreducible semantic properties. In Plato’s terms, we need the Forms.

In pursuit of this strategy of argument in 187–201, Plato rejects in turn five possible empiricist explanations of how there can be false belief. In the First Puzzle (188a–c) he proposes a basic difficulty for any empiricist. Then he argues that no move available to the empiricist circumvents this basic difficulty, however much complexity it may introduce (the other four Puzzles: 188d–201b). The Fifth Puzzle collapses back into the Third Puzzle, and the Third Puzzle collapses back into the First. The proposal that gives us the Fourth Puzzle is disproved by the counter-examples that make the Fifth Puzzle necessary. As for the Second Puzzle, Plato deploys this to show how empiricism has the disabling drawback that it turns an outrageous sophistical argument into a valid disproof of the possibility of at least some sorts of false belief.

Thus 187–201 continues the critique of perception-based accounts of knowledge that 151–187 began. Contrary to what some—for instance Cornford—have thought, it is no digression from the main path of the Theaetetus . On the contrary, the discussion of false belief is the most obvious way forward.

As Plato stresses throughout the dialogue, it is Theaetetus who is caught in this problem about false belief. It is not Socrates, nor Plato. There is clear evidence at Philebus 38c ff. that false belief (at least of some sorts) was no problem at all to Plato himself (at least at some points in his career). Plato’s question is not “How on earth can there be false judgement?” Rather it is “What sort of background assumptions about knowledge must Theaetetus be making, given that he is puzzled by the question how there can be false judgement?”

Is it only false judgements of identity that are at issue in 187–201, or is it any false judgement? One interpretation of 187–201 says that it is only about false judgements of misidentification. Call this view misidentificationism . The main alternative interpretation of 187–201 says that it is about any and every false judgement. Call this view anti-misidentificationism . The present discussion assumes the truth of anti-misidentificationism; see Chappell 2005: 154–157 for the arguments.

I turn to the detail of the five proposals about how to explain false belief that occupy Stephanus pages 187 to 200 of the dialogue.

The first proposal about how to explain the possibility of false belief is the proposal that false belief occurs when someone misidentifies one thing as another. To believe or judge falsely is to judge, for some two objects O1 and O2 , that O1 is O2 .

How can such confusions even occur? Plato presents a dilemma that seems to show that they can’t. The objects of the judgement, O1 and O2 , must either be known or unknown to the judger x . Suppose one of the objects, say O1 , is unknown to x . In that case, O1 cannot figure in x ’s thoughts at all, since x can only form judgements using objects that he knows. So if O1 is not an object known to x , x cannot make any judgement about O1 . A fortiori, then, x can make no false judgement about O1 either.

If, on the other hand, both O1 and O2 are known to x , then x can perhaps make some judgements about O1 and O2 ; but not the false judgement that “ O1 is O2 .” If x knows O1 and O2 , x must know that O1 is O1 and O2 is O2 , and that it would be a confusion to identify them. So apparently false belief is impossible if the judger does not know both O1 and O2 ; but also impossible if he does know both O1 and O2 .

I cannot mistake X for Y unless I am able to formulate thoughts about X and Y . But I will not be able to formulate thoughts about X and Y unless I am acquainted with X and Y . Being acquainted with X and Y means knowing X and Y ; and anyone who knows X and Y will not mistake them for each other.

Why think this a genuine puzzle? There seem to be plenty of everyday cases where knowing some thing in no way prevents us from sometimes mistaking that thing for something else. One example in the dialogue itself is at 191b (cp. 144c5). It is perfectly possible for someone who knows Socrates to see Theaetetus in the distance, and wrongly think that Theaetetus is Socrates. The First Puzzle does not even get off the ground, unless we can see why our knowledge of X and Y should guarantee us against mistakes about X and Y . Who is the puzzle of 188a–c supposed to be a puzzle for ?

Some authors, such as Bostock, Crombie, McDowell, and White, think that Plato himself is puzzled by this puzzle. Thus Crombie 1963: 111 thinks that Plato advances the claim that any knowledge at all of an object O is sufficient for infallibility about O because he fails to see the difference between “being acquainted with X ” and “being familiar with X .” But to confuse knowing everything about X with knowing enough about X to use the name ‘ X ’ is really a very simple mistake. Plato would not be much of a philosopher if he made this mistake.

If (as is suggested in e.g. Chappell 2004, ad loc.) 187–201 is an indirect demonstration that false belief cannot be explained by empiricism (whether this means a developed philosophical theory, or the instinctive empiricism of some people’s common sense), then it is likely that the First Puzzle states the basic difficulty for empiricism, to which the other four Puzzles look for alternative solutions. The nature of this basic difficulty is not fully, or indeed at all, explained by the First Puzzle. We have to read on and watch the development of the argument of 187–201 to see exactly what the problem is that gives the First Puzzle its bite.

The second proposal says that false judgement is believing or judging ta mê onta , “things that are not” or “what is not.” Socrates observes that if “what is not” is understood as it often was by Greek thinkers, as meaning “nothing,” then this proposal leads us straight into the sophistical absurdity that false beliefs are the same thing as beliefs about nothing (i.e., contentless beliefs). But there can be no beliefs about nothing; and there are false beliefs; so false belief isn’t the same thing as believing what is not.

Some think the Second Puzzle a mere sophistry. Bostock 1988: 165 distinguishes two versions of the sophistry: “On one version, to believe falsely is… to believe what is not ‘just by itself’; on the other version, it is to believe what is not ‘about one of the things which are’”. The argument of the first version, according to Bostock, “is just that there is no such thing as what is not (the case); it is a mere nonentity. But just as you cannot perceive a nonentity, so equally you cannot believe one either.” Bostock proposes the following solution to this problem: “We may find it natural to reply to this argument by distinguishing… propositions [from] facts, situations, states of affairs, and so on. Then we shall say that the things that are believed are propositions, not facts… so a false belief is not directed at a non-existent.”

This raises the question whether a consistent empiricist can admit the existence of propositions. At least one great modern empiricist, Quine 1953: 156–7, thinks not. Plato agrees: he regards a commitment to the existence of propositions as evidence of Platonism, acceptance of the claim that abstract objects (and plenty of them) genuinely exist. So an explanation of false judgement that invoked entities called propositions would be unavailable to the sort of empiricist that Plato has in his sights.

Bostock’s second version of the puzzle makes it an even more transparent sophistry, turning on a simple confusion between the “is” of predication and the “is” of existence. As pointed out above, we can reasonably ask whether Plato made this distinction, or made it as we make it.

If the structure of the Second Puzzle is really as Bostock suggests, then the Second Puzzle is just the old sophistry about believing what is not (cp. Parmenides DK 29B8 , Euthydemus 283e ff., Cratylus 429d, Republic 477a, Sophist 263e ff.). Moreover, on this interpretation of the Second Puzzle, Plato is committed, in his own person and with full generality, to accepting (at least provisionally) a very bad argument for the conclusion that there can be no false belief. It would be nice if an interpretation of the Second Puzzle were available that saw it differently: e.g., as accepted by him only in a context where special reasons make the Second Puzzle very plausible in that context.

One such interpretation is defended e.g., by Burnyeat 1990: 78, who suggests that the Second Puzzle can only work if we accept the “scandalous analogy between judging what is not and seeing or touching what is not there to be seen or touched”: “A model on which judgements relate to the world in the same sort of unstructured way as perceiving or (we may add) naming, will tie anyone in knots when it comes to the question ‘What is a false judgement the judgement/ name of?’. The only available answer, when the judgement is taken as an unstructured whole, appears to be: Nothing.”

Notice that it is the empiricist who will most naturally tend to rely on this analogy. It is the empiricist who finds it natural to assimilate judgement and knowledge to perception, so far as he can. So we may suggest that the Second Puzzle is a mere sophistry for any decent account of false judgement, but a good argument against the empiricist account of false judgement that Plato is attacking. The moral of the Second Puzzle is that empiricism validates the old sophistry because it treats believing or judging as too closely analogous to seeing: 188e4–7. For empiricism judgement, and thought in general, consists in awareness of the ideas that are present to our minds, exactly as they are present to our minds. It cannot consist in awareness of those ideas as they are not ; because (according to empiricism) we are immediately and incorrigibly aware of our own ideas, it can only consist in awareness of those ideas as they are . Nor can judgement consist in awareness of ideas that are not present to our minds, for (according to empiricism) what is not present to our minds cannot be a part of our thoughts. Still less can judgement consist in awareness of ideas that do not exist at all.

The old sophists took false belief as “judging what is not”; they then fallaciously slid from “judging what is not,” to “judging nothing,” to “not judging at all,” and hence concluded that no judgement that was ever actually made was a false judgement. The empiricism that Plato attacks not only repeats this logical slide; it makes it look almost reasonable. The point of the Second Puzzle is to draw out this scandalous consequence.

Literally translated, the third proposal about how to explain the possibility of false belief says that false belief occurs “when someone exchanges ( antallaxamenos ) in his understanding one of the things that are with another of the things that are, and says is ” (189b12–c2).

Perhaps the best way to read this very unclear statement is as meaning that the distinctive addition in the third proposal is the notion of inadvertency . The point of Socrates’ argument is that this addition does not help us to obtain an adequate account of false belief because thought ( dianoia ) has to be understood as an inner process, with objects that we are always fully and explicitly conscious of. If we are fully and explicitly conscious of all the objects of our thoughts, and if the objects of our thoughts are as simple as empiricism takes them to be, there is simply no room for inadvertency. But without inadvertency, the third proposal simply collapses back into the first proposal, which has already been refuted.

The empiricist conception of knowledge that Theaetetus unwittingly brings forth, and which Socrates is scrutinising, takes the objects of thought to be simple mental images which are either straightforwardly available to be thought about, or straightforwardly absent. The First Puzzle showed that there is a general problem for the empiricist about explaining how such images can be confused with each other, or indeed semantically conjoined in any way at all. The Second Puzzle showed that, because the empiricist lacks clear alternatives other than that someone should have a mental image or lack it, he is wide open to the sophistical argument which identifies believing with having a mental image , and then identifies believing what is with having a mental image , too—and so “proves” the impossibility of false belief. The Third Puzzle restricts itself (at least up to 190d7) to someone who has the requisite mental images, and adds the suggestion that he manages to confuse them by a piece of inadvertency. Socrates’ rejoinder is that nothing has been done to show how there can be inadvertent confusions of things that are as simple and unstructured, and as simply grasped or not grasped, as the empiricist takes mental images to be. Just as speech is explicit outer dialogue, so thought is explicit inner dialogue. What the empiricist needs to do to show the possibility of such a confusion is to explain how, on his principles, either speech or thought can fail to be fully explicit and fully “in touch” with its objects, if it is “in touch” with them at all.

In the discussion of the Fourth and Fifth Puzzles, Socrates and Theaetetus together work out the detail of two empiricist attempts to explain just this. It then becomes clearer why Plato does not think that the empiricist can explain the difference between fully explicit and not-fully-explicit speech or thought. Plato thinks that, to explain this, we have to abandon altogether the empiricist conception of thought as the concatenation (somehow) of semantically inert simple mental images. Instead, we have to understand thought as the syntactic concatenation of the genuine semantic entities, the Forms . Mistakes in thought will then be comprehensible as mistakes either about the logical interrelations of the Forms, or about the correct application of the Forms to the sensory phenomena.

The Wax Tablet passage offers us a more explicit account of the nature of thought, and its relationship with perception. The story now on offer says explicitly that perception relates to thought roughly as Humean “impressions” relate to Humean “ideas” (191d; compare Hume, First Enquiry II). The objects of perception, as before, are a succession of constantly-changing immediate awarenesses. The objects of thought, it is now added, are those objects of perception to which we have chosen to give a measure of stability by imprinting them on the wax tablets in our minds. (The image of memory as writing in the mind had currency in Greek thought well before Plato’s time: see e.g. Aeschylus, Eumenides 275.)

This new spelling-out of the empiricist account of thought seems to offer new resources for explaining the possibility of false belief. The new explanation can say that false belief occurs when there is a mismatch, not between two objects of thought , nor between two objects of perception , but between one object of each type.

This proposal faces a simple and decisive objection. No one disputes that there are false beliefs that cannot be explained as mismatches of thought and perception: e.g., false beliefs about arithmetic. The Wax Tablet does not explain how such false beliefs happen; indeed it entails that they can’t happen. Such mistakes are confusions of two objects of thought, and the Wax Tablet model does not dispute the earlier finding that there can be no such confusions. So the Wax Tablet model fails.

There is of course plenty more that Plato could have said in criticism of the Wax Tablet model. Most obviously, he could have pointed out the absurdity of identifying any number with any individual’s thought of that number (195e9 ff.); especially when the numerical thought in question is no more than an ossified perception. In the present passage Plato is content to refute the Wax Tablet by the simplest and shortest argument available: so he does not make this point. But perhaps the point is meant to occur to the reader; for the same absurdity reappears in an even more glaring form in the Aviary passage.

If we had a solution to the very basic problem about how the empiricist can get any content at all out of sensation, then the fourth proposal might show how the empiricist could explain false belief involving perception. The fifth and last proposal about how to explain the possibility of false belief attempts to remedy the fourth proposal’s incapacity—which Plato says refutes it, 196c5–7—to deal with cases of false belief involving no perception, such as false arithmetical beliefs.

It attempts this by deploying a distinction between knowledge that someone merely has (latent knowledge) and knowledge that he is actually using (active knowledge) . (Perhaps Plato is now exploring “the intermediate stages between knowing and not knowing” mentioned at 188a2–3.) The suggestion is that false belief occurs when someone wants to use some item of latent knowledge in his active thought, but makes a wrong selection from among the items that he knows latently.

If this proposal worked it would cover false arithmetical belief. But the proposal does not work, because it is regressive. If there is a problem about the very possibility of confusing two things, it is no answer to this problem to suppose that for each thing there is a corresponding item of knowledge, and that what happens when two things are confused is really that the two corresponding items of knowledge are confused (200a–b).

The Aviary rightly tries to explain false belief by complicating our picture of belief. But it complicates in the wrong way and the wrong place. It is no help to complicate the story by throwing in further objects of the same sort as the objects that created the difficulty about false belief in the first place. What is needed is a different sort of object for thought: a kind of object that can be thought of under different aspects (say, as “the sum of 5 and 7,” or as “the integer 12”). There are no such aspects to the “items of knowledge” that the Aviary deals in. As with the conception of the objects of thought and knowledge that we found in the Wax Tablet, it is this lack of aspects that dooms the Aviary’s conception of the objects of knowledge too. Like the Wax Tablet, the Aviary founders on its own inability to accommodate the point that thought cannot consist merely in the presentation of a series of inert “objects of thought.” Whether these objects of thought are mental images drawn from perception or something else, the thinking is not so much in the objects of thought as in what is done with those objects (186d2–4).

We may illustrate this by asking: When the dunce who supposes that 5 + 7 = 11 decides to activate some item of knowledge to be the answer to “What is the sum of 5 and 7?,” which item of knowledge does he thus decide to activate? At first only two answers seem possible: either he decides to activate 12, or he decides to activate 11. If he decides to activate 12, then we cannot explain the fact that what he actually does is activate 11, except by saying that he mistakes the item of knowledge which is 11 for the item of knowledge which is 12. But this mistake is the very mistake ruled out as impossible right at the beginning of the inquiry into false belief (188a–c). Alternatively, if he decides to activate 11, then we have to ask why he decides to do this. The most plausible answer to that question is: “Because he believes falsely that 5 + 7 = 11.” But as noted above, if he has already formed this false belief, within the account that is supposed to explain false belief, then a regress looms.

In fact, the correct answer to the question “Which item of knowledge does the dunce decide to activate?” is neither “12” nor “11.” It is “ that number which is the sum of 5 and 7.” But this answer does not save the Aviary theorist from the dilemma just pointed out; for it is not available to him. To be able to give this answer, the Aviary theorist would have to be able to distinguish “that number which is the sum of 5 and 7” from “12.” But since “12” is “ that number which is the sum of 5 and 7,” this distinction cannot be made by anyone who takes the objects of thought to be simple in the way that the Aviary theorist seems to.

At 199e1 ff. Theaetetus suggests an amendment to the Aviary. This is that we might have items of ignorance in our heads as well as items of knowledge. As Socrates remarks, these ignorance-birds can be confused with knowledge-birds in just the same way as knowledge-birds can be confused with each other. So the addition does not help.

At 200d–201c Socrates argues more directly against D2 . He offers a counter-example to the thesis that knowledge is true belief. A skilled lawyer can bring jurymen into a state of true belief without bringing them into a state of knowledge; so knowledge and true belief are different states.

McDowell 1976: 227–8 suggests that this swift argument “contradicts the most characteristic expositions of the Theory of Forms, which indicate that the title ‘knowledge’ should be reserved for a relation between the mind and the Forms untainted by any reliance on perception.” By contrast Plato here tells us, quite unambiguously, that the jury are persuaded into a state of true belief “about things which only someone who sees them can know” (201b8). This implies that there can be knowledge which is entirely reliant on perception. (One way out of this is to deny that Plato ever thought that knowledge is only of the Forms, as opposed to thinking that knowledge is paradigmatically of the Forms. For this more tolerant Platonist view about perception see e.g. Philebus 58d–62d, and Timaeus 27d ff.)

The jury argument seems to be a counter-example not only to D2 but also to D3 , the thesis that knowledge is true belief with an account (provided we allow that the jury “have an account”).

A third problem about the jury argument is that Plato seems to offer two incompatible explanations of why the jury don’t know: first that they have only a limited time to hear the arguments (201b3, 172e1); and second that their judgement is second-hand (201b9).

8. Third Definition ( D3 ): “Knowledge is True Judgement With an Account”: 201d–210a

Theaetetus’ third proposal about how to knowledge is ( D3 ) that it is true belief with an account ( meta logou alêthê doxan ).

D3 apparently does nothing at all to solve the main problems that D2 faced. Besides the jurymen counter-example just noted, 187–201 showed that we could not define knowledge as true belief unless we had an account of false belief. This problem has not just evaporated in 201–210. It will remain as long as we propose to define knowledge as true belief plus anything. Significantly, this does not seem to bother Plato—as we might expect if Plato is not even trying to offer an acceptable definition of knowledge, but is rather undermining unacceptable definitions.

One crucial question about Theaetetus 201–210 is the question whether the argument is concerned with objectual or propositional knowledge. This is a basic and central division among interpretations of the whole passage 201–210, but it is hard to discuss it properly without getting into the detail of the Dream Theory: see section 8a.

A second question, which arises often elsewhere in the Theaetetus , is whether the argument’s appearance of aporia reflects genuine uncertainty on Plato’s part, or is rather a kind of literary device. Is Plato thinking aloud, trying to clarify his own view about the nature of knowledge, as Revisionists suspect? Or is he using an aporetic argument only to smoke out his opponents, as Unitarians think?

The evidence favours the latter reading. There are a significant number of other passages where something very like Theaetetus’ claim ( D3 ) that knowledge is “true belief with an account” is not only discussed, but actually defended: for instance, Meno 98a2, Phaedo 76b5–6, Phaedo 97d–99d2, Symposium 202a5–9, Republic 534b3–7, and Timaeus 51e5. So it appears that, in the Theaetetus , Plato cannot be genuinely puzzled about what knowledge can be. Nor can he genuinely doubt his own former confidence in one version of D3 . If he does have a genuine doubt or puzzle of this sort, it is simply incredible that he should say what he does say in 201–210 without also expressing it.

What Plato does in 201–210 is: present a picture (Socrates’ Dream) of how things may be if D3 is true (201c–202c); raise objections to the Dream theory which are said (206b12) to be decisive (202c–206c); and present and reject three further suggestions about the meaning of logos , and so three more versions of D3 (206c–210a). But none of these four interpretations of D3 is Plato’s own earlier version of D3 , which says that knowledge = true belief with an account of the reason why the true belief is true . If what Plato wants to tell us in Theaetetus 201–210 is that he no longer accepts any version of D3 , not even his own version, then it is extraordinary that he does not even mention his own version, concentrating instead on versions of D3 so different from Plato’s version as to be obviously irrelevant to its refutation.

Unitarians can suggest that Plato’s strategy is to refute what he takes to be false versions of D3 so as to increase the logical pressure on anyone who rejects Plato’s version of D3 . In particular, he wants to put pressure on the empiricist theories of knowledge that seem to be the main target of the Theaetetus . What Plato wants to show is, not only that no definition of knowledge except his own, D3 , is acceptable, but also that no version of D3 except his own is acceptable.

Rather as Socrates offered to develop D1 in all sorts of surprising directions, so now he offers to develop D3 into a sophisticated theory of knowledge. This theory, usually known as the “Dream of Socrates” or the “Dream Theory,” posits two kinds of existents, complexes and simples, and proposes that “an account” means “an account of the complexes that analyses them into their simple components.” Thus “knowledge of x ” turns out to mean “true belief about x with an account of x that analyses x into its simple components.”

Taken as a general account of knowledge, the Dream Theory implies that knowledge is only of complexes, and that there can be no knowledge of simples. Socrates attacks this implication.

A common question about the Dream Theory is whether it is concerned with objectual or propositional knowledge. Those who take the Dream Theory to be concerned with propositional knowledge include Ryle 1990: 27–30: “from 201 onwards Plato concentrates on ‘know’ ( connaître ): [Socrates’ Dream] is a logician’s theory, a theory about the composition of truths and falsehoods.” Those who take the Dream Theory to be concerned with objectual knowledge include White 1976: 177, and Crombie 1963: II: 41–42; also Bostock 1988. A third way of taking the Dream Theory, which may well be the most promising interpretation, is to take it as a Logical Atomism : as a theory which founds an account of propositional structure on an account of the concatenation of simple objects of experience or acquaintance such as “sense data.”

The Logical-Atomist reading of the Dream Theory undercuts the propositional/objectual distinction. On this reading, the Dream Theory claims that simple, private objects of experience are the elements of the proposition; thus, the Dream Theory is both a theory about the structure of propositions and a theory about simple and complex objects. It claims in effect that a proposition’s structure is that of a complex object made up out of simple objects, where these simple objects are conceived in the Russellian manner as objects of inner perception or acquaintance, and the complexes which they compose are conceived in the phenomenalist manner as (epistemological and/ or semantic) constructs out of those simple objects.

This supposition makes good sense of the claim that we ourselves are examples of complexes (201e2: “the primary elements ( prôta stoikheia ) of which we and everything else are composed…”). If the Dream theorist is a Logical Atomist, he will think that there is a clear sense in which people, and everything else, are composed out of sense data. He will also think that descriptions of objects, too, are complexes constructed in another way out of the immediately available simples of sensation.

For such a theorist, epistemology and semantics alike rest upon the foundation provided by the simple objects of acquaintance. Both thought and meaning consist in the construction of complex objects out of those simple objects. Philosophical analysis, meanwhile, consists in stating how the complexes involved in thought and meaning are constructed out of simples. This statement involves, amongst other things, dividing down to and enumerating the (simple) parts of such complexes.

What then is the relation of the Dream Theory to the problems posed for empiricism by the discussion of D2 in 187–201? The fundamental problem for empiricism, as we saw, is the problem how to get from sensation to content : the problem of how we could start with bare sense-data, and build up out of them anything that deserved to be called meaning . Plato thinks that there is a good answer to this, though it is not an empiricist answer. Sense experience becomes contentful when it is understood and arranged according to the structures that the Forms give it. So to understand sense experience is, in the truest sense, “to give an account” for it.

The empiricist cannot offer this answer to the problem of how to get from sensation to content without ceasing to be an empiricist. What the empiricist can do is propose that content arises out of sets of sense experiences. We get to the level of belief and knowledge only when we start to consider such sets: before that we are at the level only of perception. Our beliefs, couched in expressions that refer to and quantify over such sets, will then become knowledge (a) when they are true, and (b) when we understand the full story of their composition out of such sets.

If this is the point of the Dream Theory, then the best answer to the question “Whose is the Dream Theory?” is “It belongs to the empiricist whom Plato is attacking.”

The Dream Theory says that knowledge of O is true belief about O plus an account of O ’s composition. If O is not composite, O cannot be known, but only “perceived” (202b6).

Socrates’ main strategy in 202d8–206c2 is to attack the Dream’s claim that complexes and elements are distinguishable in respect of knowability. To this end he deploys a dilemma. A complex, say a syllable, is either (a) no more than its elements (its letters), or (b) something over and above those elements.

202d8–203e1 shows that unacceptable consequences follow from alternative (a), that a complex is no more than its elements. If I am to know a syllable SO , and that syllable is no more than its elements, then I cannot know the syllable SO without also knowing its elements S and O . Indeed, it seems that coming to know the parts S and O is both necessary and sufficient for coming to know the syllable SO . But if that is right, and if the letter/syllable relation models the element/complex relation, then if any complex is knowable , its elements will be knowable too; and if any complex’s elements are unknowable , then the complex will be unknowable too. This result contradicts the Dream Theory.

203e2–205e8 shows that unacceptable consequences follow from alternative (b), that a complex is something over and above its elements. In that case, to know the syllable is to know something for which knowledge of the elements is not sufficient. The syllable turns out to be “a single Idea that comes to be out of the fitted-together elements” (204a1–2). But then the syllable does not have the elements as parts: if it did, that would compromise its singularity. And if the elements are not the parts of the syllable, nothing else can be. So the syllable has no parts, which makes it as simple as an element. Thus if the element is unknowable, the syllable must be unknowable too. This result contradicts the Dream Theory too.

Finally, in 206a1–c2, Plato makes a further, very simple, point against the Dream Theory. Our own experience of learning letters and syllables shows that it is both more basic and more important to know elements than complexes, not vice versa as the Dream Theory implies. The thesis that the complexes are knowable, the elements unknowable, is false to our experience, in which “knowledge of the elements is primary” (Burnyeat 1990:192).

The refutation of the Dream Theory’s attempt to spell out what it might be like for D3 to be true is followed by three attempts to give an account of what a logos is. The first attempt to give an account of “account” takes logos just to mean “speech” or “statement.” This is deemed obviously insufficient (206c1–206e3).

A second attempted explanation of “ logos of O” takes it as “enumeration of the elements of O .” The logos is a statement of the elements of the object of knowledge. You have knowledge of something when, in addition to your true belief about it, you are able also to “go through the elements” of that thing.

Plato’s objection to this proposal (208b) is that it leaves open the possibility that someone could count as having knowledge of the name “Theaetetus” even if they could do no more than write out the letters of the name “Theaetetus” in the right order. Since such a person can enumerate the elements of the complex, i.e., the letters of the name (207c8–d1), he has an account. Since he can arrange those letters in their correct order (208a9–10), he also has true belief. For all that, insists Plato, he does not have knowledge of the name “Theaetetus.”

Why not, we might ask? To see the answer we should bring in what Plato says about syllables at 207d8–208a3. Suppose someone could enumerate the letters of “Theaetetus,” and could give their correct order, and yet knew nothing about syllables. This person wouldn’t count as knowing “Theaetetus” because he would have no understanding of the principles that get us from ordered letters to names. Those principles are principles about how letters form syllables, and how syllables form names. A person who can state only the letters of “Theaetetus” and their order has no awareness of these principles.

To put it a modern way, a robot or an automatic typewriter might be able to reproduce or print the letters of “Theaetetus” correctly and in order. It might even be able to store such a correct ordering in its electronic memory. That would not show that such a machine understood how to spell “Theaetetus,” any more than the symbol-manipulating capacities of the man in Searle’s Chinese Room show that he understands Chinese. What is missing is an awareness of bridging or structuring principles, rules explaining how we get from strings of symbols, via syllables, to representations of Greek names.

Knowledge of such bridging principles can reasonably be called knowledge of why the letters of “Theaetetus” are what they are. So it is plausible to suggest that the moral of the argument is to point us to the need for an account in the sense of an explanation “Why?,” and so to the version of D3 that Plato himself accepts.

The third proposed account of logos says that to give the logos of O is to cite the sêmeion or diaphora of O . In the Wax Tablet passage, sêmeion meant ‘imprint’; in the present passage, it means the ‘sign’ or diagnostic feature wherein x differs from everything else, or everything else of O ’s own kind. So, presumably, knowledge of (say) Theaetetus consists in true belief about Theaetetus plus an account of what differentiates Theaetetus from every other human.

Socrates offers two objections to this proposal. First, if knowledge of Theaetetus requires a mention of his sêmeion , so does true belief about Theaetetus. Second, to possess “an account of Theaetetus’ sêmeion ” must mean either (a) having true belief about that sêmeion, or else (b) having knowledge of it. But it has already been pointed out that any true belief, if it is to qualify as being about Theaetetus at all, must already be true belief about his sêmeion. So interpretation (a) has the result that knowledge of Theaetetus = true belief about Theaetetus’ sêmeion + true belief about Theaetetus’ sêmeion . As for (b): if we want to know what knowledge is, it is no help to be told that knowledge of O = something else + knowledge of the sêmeion of O . We still need to know what knowledge of the sêmeion of O is. Nor will it help us to be launched on a vicious regress: as we will be if we are told that knowledge of the sêmeion of O = something else + knowledge of the sêmeion of the sêmeion of O .

This is where the argument ends, and Socrates leaves to meet his accusers.

The Theaetetus is an extended attack on certain assumptions and intuitions about knowledge that the intelligent man-in-the-street—Theaetetus, for instance—might find initially attractive, and which some philosophers known to Plato—Protagoras and Heracleitus, for instance—had worked up into complex and sophisticated philosophical theories. Basic to all these assumptions and intuitions, which here have been grouped together under the name “empiricism,” is the idea that knowledge is constructed out of perception and perception alone.

The first part of the Theaetetus attacks the idea that knowledge could be simply identified with perception. Perceptions alone have no semantic structure. So if this thesis was true, it would be impossible to state it.

The second part attacks the suggestion that knowledge can be defined as true belief, where beliefs are supposed to be semantically-structured concatenations of sensory impressions. Against this Plato argues that, unless something can be said to explain how impressions can be concatenated so as to give them semantic structure, there is no reason to grant that the distinction between true and false applies to such beliefs any more than it does to perceptions.

Finally, in the third part of the Theaetetus , an attempt is made to meet this challenge, and present some explanation of how semantic structures can arise out of mere perceptions or impressions. The proposed explanation is the Dream Theory, a theory interestingly comparable to Russellian Logical Atomism, which takes both propositions and objects to be complexes “logically constructed” out of simple sensory impressions. On this conception, knowledge will come about when someone is capable not only of using such logical constructions in thought, but of understanding how they arise from perception.

Socrates’ basic objection to this theory is that it still gives no proper explanation of how this logical construction takes place. Without such an explanation, there is no good reason to treat the complexes that are thus logically constructed as anything other than simples in their own right. We need to know how it can be that, merely by conjoining perceptions in the right way, we manage to achieve a degree of semantic structure that (for instance) makes it possible to refer to things in the world , such as Theaetetus. But this is not explained simply by listing all the simple perceptions that are so conjoined. Nor—and this is where we reach the third proposal of 208b11–210a9—is it explained by fixing on any of those perceptions in particular, and taking it to be the special mark of Theaetetus whereby reference to Theaetetus is fixed.

The third proposal about how to understand logos faces the difficulty that, if it adds anything at all to differentiate knowledge of O from true belief about O , then what it adds is a diagnostic quality of O . If there is a problem about how to identify O , there is a problem about how to identify the diagnostic quality too. This launches a vicious regress.

One way of preventing this regress is to argue that the regress is caused by the attempt to work up a definition of knowledge exclusively out of empiricist materials. Hence there is no way of avoiding such a vicious regress if you are determined to try to define knowledge on an exclusively empiricist basis. The right response is to abandon that attempt. Knowledge is indeed indefinable in empiricist terms. In those terms, it has no logos . In those terms, therefore, knowledge itself is unknowable.

The official conclusion of the Theaetetus is that we still do not know how to define knowledge. Even on the most sceptical reading, this is not to say that we have not learned anything about what knowledge is like. As Theaetetus says (210b6), he has given birth to far more than he had in him.

And as many interpreters have seen, there may be much more to the ending than that. It may even be that, in the last two pages of the Theaetetus , we have seen hints of Plato’s own answer to the puzzle. Perhaps understanding has emerged from the last discussion, as wisdom did from 145d–e, as the key ingredient without which no true beliefs alone can even begin to look like they might count as knowledge. Perhaps it is only when we, the readers, understand this point—that epistemological success in the last resort depends on having epistemological virtue—that we begin not only to have true beliefs about what knowledge is, but to understand knowledge.

References to Plato’s Theaetetus follow the pagination and lineation of E.A.Duke, W.F.Hicken, W.S.M.Nicholl, D.B.Robinson, J.C.G.Strachan, edd., Platonis Opera Tomus I.

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Plato | Plato: method and metaphysics in the Sophist and Statesman | Plato: middle period metaphysics and epistemology | Platonism: in metaphysics

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Explaining Knowledge: New Essays on the Gettier Problem

Rodrigo Borges, Claudio de Almeida, and Peter D. Klein (eds.), Explaining Knowledge: New Essays on the Gettier Problem , Oxford, 2017, 414pp., $100.00 (hbk), ISBN 9780198724551.

Reviewed by Jonathan Stoltz, University of St. Thomas

It has now been 55 years since Edmund Gettier's three-page article, "Is Justified True Belief Knowledge?", was published in Analysis . It can be argued that no other journal article in philosophy has had a more profound impact on the trajectory of philosophy than Gettier's. The article has been cited in more than 3,600 scholarly works and has spawned a number of new subfields within epistemology. Given this, one shouldn't be surprised to hear that a new book of essays on "the Gettier problem" has been published.

Let me begin by addressing one initial complaint that I can imagine being thrown at this new volume. In a world where several thousand articles already reference Gettier's 1963 paper and many hundreds of articles have already been published on the so-called Gettier problem, is it really necessary to commission and publish a book of new essays on the Gettier problem? If the book is meant to be a testament to the profound impact of Gettier's article, would not an anthology of twenty or twenty-five of the most famous articles already published on the problem have been just as worthy of publication? After all, it is difficult to defend the claim that this new book fills an existing gap in the philosophical literature. So, given that this is a collection of new essays, it is worth asking what this volume is seeking to accomplish -- what its cumulative value is -- and whether the essays deliver on that promise.

The editors' introduction provides a brief sketch of the key features of Gettier cases and walks readers through some of the most familiar lines of response. Little space, however, is devoted to offering a defense of the value of publishing these new essays. Readers are told that, "This is the perfect time to provide the philosophical community with the latest developments in the scholarship on this problem," but we are not told why this is so, or why these "latest developments" should come from new essays as opposed to recently published pieces.

In short, the introduction fails to make a compelling case for the importance of the book. This is not to say, of course, that the volume is a failure. Far from it. The twenty-three chapters are, on the whole, excellent contributions to the field of epistemology and provide a clear picture of the deep and lasting importance of the Gettier problem.

The list of contributing authors is a veritable Who's Who of contemporary epistemology. Some of the contributors -- Keith Lehrer, Alvin Goldman, Peter Klein, Fred Dretske -- were among the first wave of thinkers to publish articles that directly or indirectly responded to the Gettier problem back in the 1960s and early 1970s. But the book also includes many contributions by younger epistemologists who were born one or even two decades after the original publication of Gettier's article. The fact that the volume consists of chapters written by multiple generations of scholars reflects the lasting importance of the Gettier problem to contemporary epistemology. Among those living philosophers who have made the most significant contributions to the Gettier-problem literature, nearly all of them (setting aside Gettier himself) contributed chapters to this book. One notable exception is Timothy Williamson. His views are referenced in twelve of the twenty-three chapters, and in the editors' introduction as well. In many of those chapters Williamson's views are featured prominently. Given this, it is somewhat disappointing that Williamson did not author a chapter of his own. Nevertheless, the complete list of contributors is of the highest quality and the full collection reflects the quality of its contributors.

The essays are grouped under five themes, with four to six chapters treating each theme. The themes are: (I) Solving the Gettier Problem, (II) The Gettier Legacy, (III) Gettier and Philosophical Methodology, (IV) Gettier and Inferential Knowledge, and (V) Dissolving the Gettier Problem. It is not fully clear whether the solicited chapters were pre-assigned to these five themes, or whether the editors grouped articles together only after receiving them. Whatever the case, there are only rare occasions in which the contributors "talk" to one another within a single theme. For example, though six separate essays fall under the Part I theme of "Solving the Gettier Problem," and though the individual essays reach different conclusions about how the problem is to be solved, there are fewer occasions than one might have hoped where one of the authors references the views of other contributors whose proposed solutions to the Gettier problem differ from his or her own.

That this "talk" or "conversation" between chapters does not often occur is, it must be admitted, not particularly surprising or unusual, given the nature of collections of this sort. Yet, it is here where one wishes that the editors would have done more to showcase how each of the individual essays within a single theme fits with the other essays on that theme. It is not uncommon, for example, for edited volumes to include, at the beginning of each thematic group of essays, a short introduction to that theme that both keys readers in to the central topic at issue and walks readers through the relations between the articles in that group. But no such introductions are provided in this book. To express this mild criticism differently, this volume of essays is best construed not as a twenty-three chapter, integrated presentation of the present state of scholarship on the Gettier problem, but rather as a collection of twenty-three independent essays on the Gettier problem. In turn, this volume is more likely to be consulted by students and scholars who are looking for a specific article (capturing so-and-so's current views on the Gettier problem) than it is to be used by those who want to get a comprehensive picture of how the Gettier problem relates to broader issues in epistemology.

Having said all that, it must be emphasized that the individual articles are strong pieces of scholarship. The ten articles on "Solving the Gettier Problem" and "Dissolving the Gettier Problem" are well done, but it is the middle three parts that shine the brightest and give the best evidence of the lasting impact of Gettier's 1963 essay on current disputes. In particular, the essays on the themes of "Gettier and Philosophical Methodology" and "Gettier and Inferential Knowledge" constitute the most important contributions. The essays on the former theme grapple with two overlapping issues that have come to the fore in philosophy in recent years, and that are especially relevant to epistemology and the Gettier problem more specifically: the role of "intuition" in philosophical theorizing and the debate between "armchair" philosophy and experimental philosophy (X-Phi). Though the X-Phi movement and the recent disputes over appeals to intuitions in philosophy extend far beyond epistemology, the Gettier problem is one specific domain of inquiry where an examination of the value of intuitions (whether by philosophers or by "lay-persons") is of particular importance. The essays in this portion of the book are all on roughly the same side of the debate over the role of intuitions in philosophy, and (in very different ways) show how the Gettier problem can be used to support a productive role for intuitions in philosophy.

The essays on "Gettier and Inferential Knowledge" focus on specific principles of deductive closure and "counter-closure" in epistemology. In particular, most of the essays address some version of the thesis that, in cases of inferential reasoning, we can gain knowledge of a proposition q only if we have knowledge of the proposition p that was essential to our deductive inference from p to q . This principle of counter-closure is succinctly expressed by Branden Fitelson as (p. 313):

Counter-Closure (CC). If S competently deduces Q from her belief that P , (thereby) coming to know Q (via deductive inference), then S knew that P (and she maintained her knowledge of P throughout the inference.

Fitelson and the other contributors on this theme take up the question of whether one can possibly obtain inferential knowledge from a false belief, or whether there must be something along the lines of a "No false lemmas" constraint (or an even stronger constraint) on inferential knowledge. These chapters (both individually and in concert) serve to provide helpful syntheses of the growing literature over the past fifteen years that has argued against some version of counter-closure.

It would be neither possible nor worthwhile to discuss each and every one of the essays. As has been said, overall, the essays are very well done. To be sure, some chapters are more convincingly argued than others. Some chapters are better/more clearly written than others. Some chapters are much more squarely connected to the Gettier problem than others. But, on the whole, the essays in this book are of high quality and do serve to advance scholarship. What I shall do in the remainder of this review is zoom in on one question related to the Gettier problem and discuss how that question plays out in several of the essays.

The question to be addressed is this: What is a "Gettier case" and how should we demarcate what does and does not count as a "Gettier case"?

This may seem like a silly question on which to focus. After all, one thing that is abundantly clear from this new book is that Gettier's 1963 article has already had a lasting impact on many issues in contemporary epistemology, and the fruitfulness of Gettier's original article doesn't necessarily depend on philosophers having the "correct" understanding of what a Gettier case is. In an important sense, the value of Gettier's article is directly seen through its influence over the past fifty-five years, and this effect would not be diminished were we to discover that there is no philosophical consensus on what the Gettier problem actually is or on what counts as a Gettier case.

On the other hand, a substantial number of recent articles focus on identifying "the moral of the Gettier problem." But how philosophers understand the moral will depend heavily on how broadly or narrowly they conceive of Gettier cases. In particular, the articles on "Gettier and Philosophical Methodology" seek to draw inferences about the role of intuitions in philosophy. But what inferences can be drawn may very well hinge on how broadly one interprets the scope of Gettier cases. Peter Blouw, Wesley Buckwalter, and John Turri, in "Gettier Cases: A Taxonomy," put forward the provocative claim that we should altogether "abandon the notion of a 'Gettier case'" (p. 251).

I think that this is a mistake, and in the remainder of this review, I will show that Blouw, Buckwalter, and Turri reach their conclusion largely because they adopt such a broad understanding of "Gettier cases" that the whole notion ends up being bereft of philosophical value. Before that argument can be made, allow me, first, to propose five different ways in which one might demarcate the boundaries of Gettier cases (from the narrowest to the broadest readings):

( Gettier-baptized ) The class of Gettier cases includes all and only those (two) scenarios that are actually featured in his 1963 article.
( Infer. JTB + A ) The class of Gettier cases includes all and only those scenarios in which the subject lacks knowledge even though she forms, via inference (from a justified but false belief), a justified true belief.
( Infer. JTB ) The class of Gettier cases includes all and only those scenarios in which the subject lacks knowledge even though she forms, via inference, a justified true belief.
( JTB ) The class of Gettier cases includes all and only those scenarios in which the subject lacks knowledge even though she forms a justified true belief.
( TB ) The class of Gettier cases includes all and only those scenarios in which the subject lacks knowledge even though she forms a true belief.

This list is, no doubt, incomplete, but will suffice for my purposes.

The narrowest portrayal, (A), restricts the class of Gettier cases to just those two cases that are explicitly offered by Gettier himself and few if any philosophers defend such a narrow reading. The second proposal, (B), is not restricted to the actual scenarios described by Gettier, but it does demand that Gettier cases display the same genetic structure as is found in Gettier's original examples. In particular, Gettier cases must be situations in which the subject ends up with a justified true belief (that, nonetheless, is not knowledge), and in which this belief is reached via an inference from a justified false belief. Philosophers adopting this interpretation are inclined to place important weight on two assumptions -- (a) the fallibility of justification and (b) the closure of justification through known entailments -- both of which are explicitly affirmed by Gettier. Many of the essays appear to adopt an interpretation along the lines of (B), but this is clearest in Rodrigo Borges' "Inferential Knowledge and the Gettier Conjecture," where he repeatedly speaks of "Gettier's blueprint," which involves assumptions (a) and (b) above.

Some philosophers may claim that proposal (B) misses the point of Gettier's original article. Gettier's objective, after all, was to show that the justified true belief analysis of knowledge cannot be correct. Insofar as this is the case, it can be argued that what is truly essential to a Gettier case is not the genetic structure, but only the fact that a person forms a justified true belief but does not possess knowledge. In other words, what matters is not the way in which the belief is formed -- e.g., via inference from a justified false belief -- but only the fact that the relevant belief is justified and true . . . and yet not an instance of knowledge. This way of understanding Gettier cases, (D), can be seen in numerous recent articles. Now, it should be obvious that proposal (D) accepts many scenarios that would not count under proposal (B). In turn, the "moral" of the Gettier problem will likely be interpreted differently by proponents of (D) than it is by proponents of (B).

As I have said, many authors in this volume implicitly support an understanding of Gettier cases that fall along the lines of proposal (B). Those include not just Borges but perhaps also all those thinkers who are primarily concerned with the fallibility of justification, including Peter Klein, Robert Shope, Keith Lehrer, and others. For them, the explanatory value of Gettier cases is tied to the very assumptions that Gettier himself made about the nature of justification -- and, in particular, the key assumption that a justified belief can still be false.

Blouw, Buckwalter, and Turri, by contrast, adopt an interpretation of 'Gettier cases' that is far broader in scope. It is at least as broad as proposal (D), and potentially broader. They include in their taxonomy scenarios that do not involve inferential beliefs at all, and scenarios where the subject may hold no (relevant) false belief. Their interpretation includes as a Gettier case the classical example from Carl Ginet (via Goldman) of papier-mâché facades of red barns -- a scenario that would not be considered a Gettier case at all under proposal (B). Moreover, in their taxonomy, they do not even specify that the beliefs in question are justified. (In none of the examples they provide, nor in any of the five categories of Gettier cases that they propose, do they mention "justification" at all.) In this respect, their understanding of Gettier cases is so broad that it may very well include mere true beliefs (such as in their 'Gettier Category 5').

Given how broadly they interpret the concept of a Gettier case, and given that they don't even refer to the concept of justification when specifying their different categories, it is not at all surprising that they fail to find any predictive or explanatory value in the notion of a Gettier case. It is also not surprising that two of their categories -- 'Gettier Category 1' where there is no relevant false belief at all, and 'Gettier Category 5' where it is far from clear that the subject's belief is even justified -- were not. in experimental tests, judged to be (statistically) significantly different from control cases of knowledge and ignorance. They take all this as evidence that " there is no one thing that counts as a Gettier case " and that "the nominal category 'Gettier case' lacks explanatory value" (p. 251). I, by contrast, take their results as evidence that they have adopted a far too broad understanding of what counts as a 'Gettier case' and have indiscriminately lumped together many kinds of scenarios that should not be considered Gettier cases at all.

Be that as it may, the fact that the parameters of Gettier cases are still up for debate illustrates the importance of philosophers continuing to grapple with, and identify the lessons to be learned from, Gettier's article. But the article's ongoing importance was not really in dispute, as is seen from the diversity and strength of the articles collected together in this new book.

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Is Knowledge Justified True Belief?: [Essay Example], 684 words
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7.2 Knowledge
Fixing Plato's Traditional Account of Knowledge. Gettier cases demonstrate that Plato 's traditional account of knowledge as justified true belief is wrong. Specifically, Gettier cases show that a belief being true and justified is not sufficient for that belief to count as knowledge. In all the cases discussed, the subject seems to have a justified true belief but not knowledge.
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PDF Is Knowledge Justified True Belief?
Abstract: Is knowledge justified true belief? Most philo-sophers believe that the answer is clearly 'no', as demon-strated by Gettier cases. But Gettier cases don't obviously refute the traditional view that knowledge is justified true belief (JTB). There are ways of resisting Gettier cases, at least one of which is partly successful. Never-
A Priori Justification and Knowledge
A priori justification is a type of epistemic justification that is, in some sense, independent of experience. Gettier examples have led most philosophers to think that having a justified true belief is not sufficient for knowledge (see Section 4.4, below, and the examples there), but many still believe that it is necessary.In this entry, it will be assumed, for the most part, that even though ...
Is Justified True Belief Knowledge? Essay Questions
Is Justified True Belief Knowledge? Essay Questions. Edmund L. Gettier. 1. Construct a Gettier counterexample of your own to the claim that justified true belief is knowledge. Explain why it is a counterexample. 2. Explain why Gettier's case satisfies Ayer's definition of knowledge (in the previous reading) and why it provides a ...
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being justified to vary according to the individual's context and goals, thereby possibly making justification and knowledge more accessible than other JTB.accounts. Finally, I will conclude that we ought to preserve the concept of knowledge as roughly that of justified true belief, but that our set of cognitive values and ideals
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What is knowledge? I this paper I defend the claim that knowledge is justified true belief by arguing that, contrary to common belief, Gettier cases do not refute it. My defence will be of the anti-luck kind: I will argue that (1) Gettier cases necessarily involve veritic luck, and (2) that a plausible version of reliabilism excludes veritic luck. There is thus a prominent and plausible ...
PDF Is Justified True Belief Knowledge?
EDMUND GETTIER. Edmund Gettier is Professor Emeritus at the University of Massachusetts, Amherst. This short piece, published in 1963, seemed to many decisively to refute an otherwise attractive analysis of knowledge. It stimulated a renewed effort, still ongoing, to clarify exactly what knowledge comprises.
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Plato on Knowledge in the Theaetetus
Knowledge is "true belief with an account (logos)" ... is the empiricist, who thinks that we acquire all our concepts by exposure to examples of their application: Locke, Essay II.1, Aristotle, Posterior Analytics 100a4-9. For the Platonist, definition by examples is never even possible; for the empiricist, definition by examples is the ...
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Abstract. Is knowledge justified true belief? Most philosophers believe that the answer is clearly 'no', as demonstrated by Gettier cases. But Gettier cases don't obviously refute the traditional view that knowledge is justified true belief (JTB). There are ways of resisting Gettier cases, at least one of which is partly successful.
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Gettier's objective, after all, was to show that the justified true belief analysis of knowledge cannot be correct. Insofar as this is the case, it can be argued that what is truly essential to a Gettier case is not the genetic structure, but only the fact that a person forms a justified true belief but does not possess knowledge.
PDF Is Justified True Belief Knowledge? Edmund L. Gettier Analysis, Vol. 23
true, even though (i) (h) is true, (ii) Smith does believe that (h) is true, and (iii) Smith is justified in believing that (h) is true. These two examples show that definition (a) does not state a szflcient condition for someone's knowing a given proposition. The same cases, with appropriate changes, will suffice to show that neither definition

Is Knowledge Justified True Belief?

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7.2 Knowledge

Plato and the Traditional Account of Knowledge

Problems with the Traditional Account of Knowledge

Dharmakīrti’s Mirage

Russell’s Case

Fake Barn Country

Fixing Plato’s Traditional Account of Knowledge

No False Premises

Ruling Out Defeaters and Alternatives

The Problem with Justification

Knowledge as Justified True Belief

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Knowledge as Objectively Justified Belief

Justification

1 Introduction

2 Gettier Cases Involve Veritic Luck

3 A Modal Interpretation of Reliabilism

4 Lotteries, Evil Demons and Other Objections

5 Similar Strategies

6 Further Implications

7 Conclusion

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Plato on Knowledge in the Theaetetus

1. Introduction

6. First Definition ( D1 ): “Knowledge is Perception”: 151e–187a

7. Second Definition ( D2 ): “Knowledge is True Judgement”: 187b–201c

8. Third Definition ( D3 ): “Knowledge is True Judgement With an Account”: 201d–210a

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Is knowledge justified true belief?

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Explaining Knowledge: New Essays on the Gettier Problem

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