hypothesis and theories

This is the Difference Between a Hypothesis and a Theory

What to Know A hypothesis is an assumption made before any research has been done. It is formed so that it can be tested to see if it might be true. A theory is a principle formed to explain the things already shown in data. Because of the rigors of experiment and control, it is much more likely that a theory will be true than a hypothesis.

As anyone who has worked in a laboratory or out in the field can tell you, science is about process: that of observing, making inferences about those observations, and then performing tests to see if the truth value of those inferences holds up. The scientific method is designed to be a rigorous procedure for acquiring knowledge about the world around us.

In scientific reasoning, a hypothesis is constructed before any applicable research has been done. A theory, on the other hand, is supported by evidence: it's a principle formed as an attempt to explain things that have already been substantiated by data.

Toward that end, science employs a particular vocabulary for describing how ideas are proposed, tested, and supported or disproven. And that's where we see the difference between a hypothesis and a theory .

A hypothesis is an assumption, something proposed for the sake of argument so that it can be tested to see if it might be true.

In the scientific method, the hypothesis is constructed before any applicable research has been done, apart from a basic background review. You ask a question, read up on what has been studied before, and then form a hypothesis.

What is a Hypothesis?

A hypothesis is usually tentative, an assumption or suggestion made strictly for the objective of being tested.

When a character which has been lost in a breed, reappears after a great number of generations, the most probable hypothesis is, not that the offspring suddenly takes after an ancestor some hundred generations distant, but that in each successive generation there has been a tendency to reproduce the character in question, which at last, under unknown favourable conditions, gains an ascendancy. Charles Darwin, On the Origin of Species , 1859 According to one widely reported hypothesis , cell-phone transmissions were disrupting the bees' navigational abilities. (Few experts took the cell-phone conjecture seriously; as one scientist said to me, "If that were the case, Dave Hackenberg's hives would have been dead a long time ago.") Elizabeth Kolbert, The New Yorker , 6 Aug. 2007

What is a Theory?

A theory , in contrast, is a principle that has been formed as an attempt to explain things that have already been substantiated by data. It is used in the names of a number of principles accepted in the scientific community, such as the Big Bang Theory . Because of the rigors of experimentation and control, its likelihood as truth is much higher than that of a hypothesis.

It is evident, on our theory , that coasts merely fringed by reefs cannot have subsided to any perceptible amount; and therefore they must, since the growth of their corals, either have remained stationary or have been upheaved. Now, it is remarkable how generally it can be shown, by the presence of upraised organic remains, that the fringed islands have been elevated: and so far, this is indirect evidence in favour of our theory . Charles Darwin, The Voyage of the Beagle , 1839 An example of a fundamental principle in physics, first proposed by Galileo in 1632 and extended by Einstein in 1905, is the following: All observers traveling at constant velocity relative to one another, should witness identical laws of nature. From this principle, Einstein derived his theory of special relativity. Alan Lightman, Harper's , December 2011

Non-Scientific Use

In non-scientific use, however, hypothesis and theory are often used interchangeably to mean simply an idea, speculation, or hunch (though theory is more common in this regard):

The theory of the teacher with all these immigrant kids was that if you spoke English loudly enough they would eventually understand. E. L. Doctorow, Loon Lake , 1979 Chicago is famous for asking questions for which there can be no boilerplate answers. Example: given the probability that the federal tax code, nondairy creamer, Dennis Rodman and the art of mime all came from outer space, name something else that has extraterrestrial origins and defend your hypothesis . John McCormick, Newsweek , 5 Apr. 1999 In his mind's eye, Miller saw his case suddenly taking form: Richard Bailey had Helen Brach killed because she was threatening to sue him over the horses she had purchased. It was, he realized, only a theory , but it was one he felt certain he could, in time, prove. Full of urgency, a man with a mission now that he had a hypothesis to guide him, he issued new orders to his troops: Find out everything you can about Richard Bailey and his crowd. Howard Blum, Vanity Fair , January 1995

And sometimes one term is used as a genus, or a means for defining the other:

Laplace's popular version of his astronomy, the Système du monde , was famous for introducing what came to be known as the nebular hypothesis , the theory that the solar system was formed by the condensation, through gradual cooling, of the gaseous atmosphere (the nebulae) surrounding the sun. Louis Menand, The Metaphysical Club , 2001 Researchers use this information to support the gateway drug theory — the hypothesis that using one intoxicating substance leads to future use of another. Jordy Byrd, The Pacific Northwest Inlander , 6 May 2015 Fox, the business and economics columnist for Time magazine, tells the story of the professors who enabled those abuses under the banner of the financial theory known as the efficient market hypothesis . Paul Krugman, The New York Times Book Review , 9 Aug. 2009

Incorrect Interpretations of "Theory"

Since this casual use does away with the distinctions upheld by the scientific community, hypothesis and theory are prone to being wrongly interpreted even when they are encountered in scientific contexts—or at least, contexts that allude to scientific study without making the critical distinction that scientists employ when weighing hypotheses and theories.

The most common occurrence is when theory is interpreted—and sometimes even gleefully seized upon—to mean something having less truth value than other scientific principles. (The word law applies to principles so firmly established that they are almost never questioned, such as the law of gravity.)

This mistake is one of projection: since we use theory in general use to mean something lightly speculated, then it's implied that scientists must be talking about the same level of uncertainty when they use theory to refer to their well-tested and reasoned principles.

The distinction has come to the forefront particularly on occasions when the content of science curricula in schools has been challenged—notably, when a school board in Georgia put stickers on textbooks stating that evolution was "a theory, not a fact, regarding the origin of living things." As Kenneth R. Miller, a cell biologist at Brown University, has said , a theory "doesn’t mean a hunch or a guess. A theory is a system of explanations that ties together a whole bunch of facts. It not only explains those facts, but predicts what you ought to find from other observations and experiments.”

While theories are never completely infallible, they form the basis of scientific reasoning because, as Miller said "to the best of our ability, we’ve tested them, and they’ve held up."

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Alchem Learning

Similarities and Differences Between Hypothesis and Theory

In the realm of scientific inquiry, two terms that are often used interchangeably but hold distinct meanings are “hypothesis” and “theory.” Both play crucial roles in the scientific method, contributing to the understanding and advancement of knowledge. This article delves into the similarities and differences between these two fundamental scientific concepts.

Hypothesis: The Starting Point

A hypothesis is a proposed explanation for a phenomenon. It is an educated guess or a tentative solution to a problem based on existing knowledge. Scientists formulate hypotheses to guide their research and make predictions that can be tested through experimentation or observation.

Characteristics

• Testability: A good hypothesis is testable, meaning it can be investigated through empirical methods.
• Falsifiability: It should be possible to prove the hypothesis false through experimentation or observation.
• Specificity: The hypothesis must be clear and specific, outlining the expected outcome of the experiment.

If plants receive more sunlight, then their growth rate will increase.

Theory: A Comprehensive Explanation

On the other hand, a theory is a well-substantiated explanation of some aspect of the natural world. Unlike a hypothesis, a theory has withstood extensive testing and scrutiny, providing a comprehensive framework for understanding a particular phenomenon.

• Explanatory Power: Theories explain a wide range of phenomena and observations.
• Predictive Capability: They can predict future observations and experiments accurately.
• Consistency: The components of a theory are internally consistent and align with existing scientific knowledge.

The theory of evolution explains the biodiversity of life through the processes of natural selection and genetic variation.

Similarities

1. both guide scientific inquiry.

Both hypotheses and theories play integral roles in the scientific method, guiding researchers in the pursuit of knowledge. Hypotheses set the initial direction for experiments, while theories provide overarching frameworks.

2. Subject to Revision

Scientific knowledge is dynamic, and both hypotheses and theories are subject to revision based on new evidence. As more data becomes available, scientists may refine or even discard hypotheses and theories.

Differences

1. level of certainty.

The primary distinction lies in the level of certainty associated with each term. A hypothesis is a tentative explanation that requires testing, while a theory is a well-established explanation supported by a substantial body of evidence.

Hypotheses are narrow in scope, addressing specific questions or problems, while theories have a broader scope, encompassing a wide range of related phenomena.

In conclusion, hypotheses and theories are essential components of the scientific process, each serving distinct roles. Hypotheses initiate investigations, while theories provide robust explanations for observed phenomena. Recognizing the differences and similarities between these concepts is crucial for understanding how scientific knowledge evolves and progresses.

Related References:

• Scientific Method – Wikipedia
• Understanding Science – University of California Museum of Paleontology
• The Difference Between Hypothesis and Theory – ThoughtCo

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Hypothesis vs. Theory

A hypothesis is either a suggested explanation for an observable phenomenon, or a reasoned prediction of a possible causal correlation among multiple phenomena. In science , a theory is a tested, well-substantiated, unifying explanation for a set of verified, proven factors. A theory is always backed by evidence; a hypothesis is only a suggested possible outcome, and is testable and falsifiable.

Comparison chart

Examples of Theory and Hypothesis

Theory: Einstein's theory of relativity is a theory because it has been tested and verified innumerable times, with results consistently verifying Einstein's conclusion. However, simply because Einstein's conclusion has become a theory does not mean testing of this theory has stopped; all science is ongoing. See also the Big Bang theory , germ theory , and climate change .

Hypothesis: One might think that a prisoner who learns a work skill while in prison will be less likely to commit a crime when released. This is a hypothesis, an "educated guess." The scientific method can be used to test this hypothesis, to either prove it is false or prove that it warrants further study. (Note: Simply because a hypothesis is not found to be false does not mean it is true all or even most of the time. If it is consistently true after considerable time and research, it may be on its way to becoming a theory.)

This video further explains the difference between a theory and a hypothesis:

Common Misconception

People often tend to say "theory" when what they're actually talking about is a hypothesis. For instance, "Migraines are caused by drinking coffee after 2 p.m. — well, it's just a theory, not a rule."

This is actually a logically reasoned proposal based on an observation — say 2 instances of drinking coffee after 2 p.m. caused a migraine — but even if this were true, the migraine could have actually been caused by some other factors.

Because this observation is merely a reasoned possibility, it is testable and can be falsified — which makes it a hypothesis, not a theory.

• What is a Scientific Hypothesis? - LiveScience
• Wikipedia:Scientific theory

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Comments: Hypothesis vs Theory

Anonymous comments (2).

October 11, 2013, 1:11pm "In science, a theory is a well-substantiated, unifying explanation for a set of verified, proven hypotheses." But there's no such thing as "proven hypotheses". Hypotheses can be tested/falsified, they can't be "proven". That's just not how science works. Logical deductions based on axioms can be proven, but not scientific hypotheses. On top of that I find it somewhat strange to claim that a theory doesn't have to be testable, if it's built up from hypotheses, which DO have to be testable... — 80.✗.✗.139

May 6, 2014, 11:45pm "Evolution is a theory, not a fact, regarding the origin of living things." this statement is poorly formed because it implies that a thing is a theory until it gets proven and then it is somehow promoted to fact. this is just a misunderstanding of what the words mean, and of how science progresses generally. to say that a theory is inherently dubious because "it isn't a fact" is pretty much a meaningless statement. no expression which qualified as a mere fact could do a very good job of explaining the complicated process by which species have arisen on Earth over the last billion years. in fact, if you claimed that you could come up with such a single fact, now THAT would be dubious! everything we observe in nature supports the theory of evolution, and nothing we observe contradicts it. when you can say this about a theory, it's a pretty fair bet that the theory is correct. — 71.✗.✗.151

• Accuracy vs Precision
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scientific hypothesis

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• National Center for Biotechnology Information - PubMed Central - On the scope of scientific hypotheses
• LiveScience - What is a scientific hypothesis?
• The Royal Society - Open Science - On the scope of scientific hypotheses

scientific hypothesis , an idea that proposes a tentative explanation about a phenomenon or a narrow set of phenomena observed in the natural world. The two primary features of a scientific hypothesis are falsifiability and testability, which are reflected in an “If…then” statement summarizing the idea and in the ability to be supported or refuted through observation and experimentation. The notion of the scientific hypothesis as both falsifiable and testable was advanced in the mid-20th century by Austrian-born British philosopher Karl Popper .

The formulation and testing of a hypothesis is part of the scientific method , the approach scientists use when attempting to understand and test ideas about natural phenomena. The generation of a hypothesis frequently is described as a creative process and is based on existing scientific knowledge, intuition , or experience. Therefore, although scientific hypotheses commonly are described as educated guesses, they actually are more informed than a guess. In addition, scientists generally strive to develop simple hypotheses, since these are easier to test relative to hypotheses that involve many different variables and potential outcomes. Such complex hypotheses may be developed as scientific models ( see scientific modeling ).

Depending on the results of scientific evaluation, a hypothesis typically is either rejected as false or accepted as true. However, because a hypothesis inherently is falsifiable, even hypotheses supported by scientific evidence and accepted as true are susceptible to rejection later, when new evidence has become available. In some instances, rather than rejecting a hypothesis because it has been falsified by new evidence, scientists simply adapt the existing idea to accommodate the new information. In this sense a hypothesis is never incorrect but only incomplete.

The investigation of scientific hypotheses is an important component in the development of scientific theory . Hence, hypotheses differ fundamentally from theories; whereas the former is a specific tentative explanation and serves as the main tool by which scientists gather data, the latter is a broad general explanation that incorporates data from many different scientific investigations undertaken to explore hypotheses.

Countless hypotheses have been developed and tested throughout the history of science . Several examples include the idea that living organisms develop from nonliving matter, which formed the basis of spontaneous generation , a hypothesis that ultimately was disproved (first in 1668, with the experiments of Italian physician Francesco Redi , and later in 1859, with the experiments of French chemist and microbiologist Louis Pasteur ); the concept proposed in the late 19th century that microorganisms cause certain diseases (now known as germ theory ); and the notion that oceanic crust forms along submarine mountain zones and spreads laterally away from them ( seafloor spreading hypothesis ).

Hypothesis vs. Theory

What's the difference.

Hypothesis and theory are two terms commonly used in scientific research, but they have distinct meanings and purposes. A hypothesis is a proposed explanation or prediction for a specific phenomenon or observation. It is based on limited evidence and serves as a starting point for further investigation. In contrast, a theory is a well-substantiated explanation that has been extensively tested and supported by a wide range of evidence. It is a comprehensive framework that explains a broad set of phenomena and is widely accepted within the scientific community. While a hypothesis is more tentative and subject to change, a theory represents a higher level of confidence and understanding in the scientific field.

Further Detail

Introduction.

In the realm of scientific inquiry, hypotheses and theories play crucial roles in the development and understanding of knowledge. While both are essential components of the scientific method, they differ in their scope, level of evidence, and the degree of generalization they offer. This article aims to explore and compare the attributes of hypotheses and theories, shedding light on their distinct characteristics and their contributions to scientific progress.

Hypothesis: The Foundation of Scientific Inquiry

A hypothesis is a proposed explanation or prediction for a specific phenomenon or observation. It serves as the initial step in the scientific method, where researchers formulate educated guesses based on existing knowledge and observations. Hypotheses are typically testable and falsifiable, allowing scientists to design experiments or gather data to either support or reject them.

One key attribute of a hypothesis is its specificity. It focuses on a particular aspect of a phenomenon and aims to explain or predict it. For example, a hypothesis might propose that increased exposure to sunlight leads to higher vitamin D levels in humans. This hypothesis is specific to the relationship between sunlight and vitamin D, providing a clear direction for further investigation.

Furthermore, hypotheses are often based on preliminary evidence or observations. They are formulated to address gaps in knowledge or to explain puzzling phenomena. Hypotheses can be derived from existing theories or can emerge from exploratory research. They serve as the foundation for scientific inquiry, guiding researchers towards the collection of empirical evidence.

It is important to note that a hypothesis is not considered a proven fact, even if it is supported by initial evidence. It requires rigorous testing and validation through experimentation and data analysis. If a hypothesis withstands repeated testing and scrutiny, it may evolve into a theory.

Theory: A Comprehensive Explanation

A theory, in the scientific context, is a well-substantiated explanation that encompasses a wide range of observations, experiments, and hypotheses. Unlike a hypothesis, a theory is supported by a substantial body of evidence and has withstood extensive testing and scrutiny. Theories provide a comprehensive framework for understanding natural phenomena and have a higher level of generalization compared to hypotheses.

One key attribute of a theory is its ability to explain and predict a broad range of related phenomena. For example, the theory of evolution by natural selection explains the diversity of life on Earth, the fossil record, and the similarities between different species. Theories are built upon a foundation of multiple lines of evidence, including experimental data, observational studies, and mathematical models.

Theories are also subject to revision and refinement as new evidence emerges. However, this does not undermine their validity or significance. The process of scientific inquiry involves constantly challenging and refining existing theories to accommodate new findings. Theories are not static, but rather dynamic frameworks that adapt to incorporate new knowledge.

Moreover, theories are widely accepted within the scientific community due to their robustness and explanatory power. They have undergone rigorous peer review and scrutiny, ensuring that they meet the highest standards of scientific integrity. Theories provide a solid foundation for further research and serve as a basis for the development of new hypotheses.

Comparing Hypotheses and Theories

While hypotheses and theories share the common goal of explaining natural phenomena, they differ in several key attributes. Let's explore some of the main points of comparison:

Scope and Generalization

Hypotheses are typically narrow in scope, focusing on specific aspects of a phenomenon. They aim to explain or predict a particular observation or relationship. In contrast, theories have a broader scope and offer a higher level of generalization. They provide comprehensive explanations that encompass multiple phenomena and observations.

Evidence and Testing

Hypotheses are formulated based on preliminary evidence or observations. They serve as starting points for scientific investigation and require empirical testing to determine their validity. Hypotheses are often tested through experiments, data analysis, or observational studies. Theories, on the other hand, are supported by a substantial body of evidence. They have withstood extensive testing and scrutiny, incorporating multiple lines of evidence from various sources.

Level of Certainty

Due to their preliminary nature, hypotheses do not offer a high level of certainty. They are educated guesses that require further testing and validation. In contrast, theories provide a higher level of certainty and confidence. They are well-substantiated explanations that have been extensively tested and supported by a wide range of evidence.

Development and Evolution

Hypotheses are often derived from existing theories or emerge from exploratory research. They serve as the initial step in scientific inquiry and can evolve into theories if supported by substantial evidence. Theories, on the other hand, are the result of extensive research, testing, and refinement. They are dynamic frameworks that adapt to incorporate new evidence and insights.

Acceptance and Consensus

While hypotheses are subject to individual interpretation and may vary among researchers, theories are widely accepted within the scientific community. Theories have undergone rigorous peer review and scrutiny, ensuring a high level of consensus among experts. They provide a solid foundation for scientific understanding and guide further research.

In summary, hypotheses and theories are integral components of the scientific method, each serving distinct roles in the pursuit of knowledge. Hypotheses provide specific explanations or predictions for phenomena and act as the initial step in scientific inquiry. They require empirical testing and validation to determine their validity. Theories, on the other hand, offer comprehensive explanations that encompass a wide range of observations and have withstood extensive testing. They provide a higher level of generalization and serve as the foundation for scientific understanding. While hypotheses and theories differ in their scope, level of evidence, and generalization, they both contribute to the advancement of scientific knowledge and our understanding of the natural world.

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Scientific Theory Definition and Examples

A scientific theory is a well-established explanation of some aspect of the natural world. Theories come from scientific data and multiple experiments. While it is not possible to prove a theory, a single contrary result using the scientific method can disprove it. In other words, a theory is testable and falsifiable.

Examples of Scientific Theories

There are many scientific theory in different disciplines:

• Astronomy : theory of stellar nucleosynthesis , theory of stellar evolution
• Biology : cell theory, theory of evolution, germ theory, dual inheritance theory
• Chemistry : atomic theory, Bronsted Lowry acid-base theory , kinetic molecular theory of gases , Lewis acid-base theory , molecular theory, valence bond theory
• Geology : climate change theory, plate tectonics theory
• Physics : Big Bang theory, perturbation theory, theory of relativity, quantum field theory

Criteria for a Theory

In order for an explanation of the natural world to be a theory, it meets certain criteria:

• A theory is falsifiable. At some point, a theory withstands testing and experimentation using the scientific method.
• A theory is supported by lots of independent evidence.
• A theory explains existing experimental results and predicts outcomes of new experiments at least as well as other theories.

Difference Between a Scientific Theory and Theory

Usually, a scientific theory is just called a theory. However, a theory in science means something different from the way most people use the word. For example, if frogs rain down from the sky, a person might observe the frogs and say, “I have a theory about why that happened.” While that theory might be an explanation, it is not based on multiple observations and experiments. It might not be testable and falsifiable. It’s not a scientific theory (although it could eventually become one).

Value of Disproven Theories

Even though some theories are incorrect, they often retain value.

For example, Arrhenius acid-base theory does not explain the behavior of chemicals lacking hydrogen that behave as acids. The Bronsted Lowry and Lewis theories do a better job of explaining this behavior. Yet, the Arrhenius theory predicts the behavior of most acids and is easier for people to understand.

Another example is the theory of Newtonian mechanics. The theory of relativity is much more inclusive than Newtonian mechanics, which breaks down in certain frames of reference or at speeds close to the speed of light . But, Newtonian mechanics is much simpler to understand and its equations apply to everyday behavior.

Difference Between a Scientific Theory and a Scientific Law

The scientific method leads to the formulation of both scientific theories and laws . Both theories and laws are falsifiable. Both theories and laws help with making predictions about the natural world. However, there is a key difference.

A theory explains why or how something works, while a law describes what happens without explaining it. Often, you see laws written in the form of equations or formulas.

Theories and laws are related, but theories never become laws or vice versa.

Theory vs Hypothesis

A hypothesis is a proposition that is tested via an experiment. A theory results from many, many tested hypotheses.

Theory vs Fact

Theories depend on facts, but the two words mean different things. A fact is an irrefutable piece of evidence or data. Facts never change. A theory, on the other hand, may be modified or disproven.

Difference Between a Theory and a Model

Both theories and models allow a scientist to form a hypothesis and make predictions about future outcomes. However, a theory both describes and explains, while a model only describes. For example, a model of the solar system shows the arrangement of planets and asteroids in a plane around the Sun, but it does not explain how or why they got into their positions.

• Frigg, Roman (2006). “ Scientific Representation and the Semantic View of Theories .”  Theoria . 55 (2): 183–206. 
• Halvorson, Hans (2012). “What Scientific Theories Could Not Be.”  Philosophy of Science . 79 (2): 183–206. doi: 10.1086/664745
• McComas, William F. (December 30, 2013).  The Language of Science Education: An Expanded Glossary of Key Terms and Concepts in Science Teaching and Learning . Springer Science & Business Media. ISBN 978-94-6209-497-0.
• National Academy of Sciences (US) (1999). Science and Creationism: A View from the National Academy of Sciences (2nd ed.). National Academies Press. doi: 10.17226/6024  ISBN 978-0-309-06406-4. 
• Suppe, Frederick (1998). “Understanding Scientific Theories: An Assessment of Developments, 1969–1998.”  Philosophy of Science . 67: S102–S115. doi: 10.1086/392812

Related Posts

Theories, Hypotheses, and Laws: Definitions, examples, and their roles in science

by Anthony Carpi, Ph.D., Anne E. Egger, Ph.D.

Listen to this reading

Did you know that the idea of evolution had been part of Western thought for more than 2,000 years before Charles Darwin was born? Like many theories, the theory of evolution was the result of the work of many different scientists working in different disciplines over a period of time.

A scientific theory is an explanation inferred from multiple lines of evidence for some broad aspect of the natural world and is logical, testable, and predictive.

As new evidence comes to light, or new interpretations of existing data are proposed, theories may be revised and even change; however, they are not tenuous or speculative.

A scientific hypothesis is an inferred explanation of an observation or research finding; while more exploratory in nature than a theory, it is based on existing scientific knowledge.

A scientific law is an expression of a mathematical or descriptive relationship observed in nature.

Imagine yourself shopping in a grocery store with a good friend who happens to be a chemist. Struggling to choose between the many different types of tomatoes in front of you, you pick one up, turn to your friend, and ask her if she thinks the tomato is organic . Your friend simply chuckles and replies, "Of course it's organic!" without even looking at how the fruit was grown. Why the amused reaction? Your friend is highlighting a simple difference in vocabulary. To a chemist, the term organic refers to any compound in which hydrogen is bonded to carbon. Tomatoes (like all plants) are abundant in organic compounds – thus your friend's laughter. In modern agriculture, however, organic has come to mean food items grown or raised without the use of chemical fertilizers, pesticides, or other additives.

So who is correct? You both are. Both uses of the word are correct, though they mean different things in different contexts. There are, of course, lots of words that have more than one meaning (like bat , for example), but multiple meanings can be especially confusing when two meanings convey very different ideas and are specific to one field of study.

• Scientific theories

The term theory also has two meanings, and this double meaning often leads to confusion. In common language, the term theory generally refers to speculation or a hunch or guess. You might have a theory about why your favorite sports team isn't playing well, or who ate the last cookie from the cookie jar. But these theories do not fit the scientific use of the term. In science, a theory is a well-substantiated and comprehensive set of ideas that explains a phenomenon in nature. A scientific theory is based on large amounts of data and observations that have been collected over time. Scientific theories can be tested and refined by additional research , and they allow scientists to make predictions. Though you may be correct in your hunch, your cookie jar conjecture doesn't fit this more rigorous definition.

All scientific disciplines have well-established, fundamental theories . For example, atomic theory describes the nature of matter and is supported by multiple lines of evidence from the way substances behave and react in the world around us (see our series on Atomic Theory ). Plate tectonic theory describes the large scale movement of the outer layer of the Earth and is supported by evidence from studies about earthquakes , magnetic properties of the rocks that make up the seafloor , and the distribution of volcanoes on Earth (see our series on Plate Tectonic Theory ). The theory of evolution by natural selection , which describes the mechanism by which inherited traits that affect survivability or reproductive success can cause changes in living organisms over generations , is supported by extensive studies of DNA , fossils , and other types of scientific evidence (see our Charles Darwin series for more information). Each of these major theories guides and informs modern research in those fields, integrating a broad, comprehensive set of ideas.

So how are these fundamental theories developed, and why are they considered so well supported? Let's take a closer look at some of the data and research supporting the theory of natural selection to better see how a theory develops.

Comprehension Checkpoint

• The development of a scientific theory: Evolution and natural selection

The theory of evolution by natural selection is sometimes maligned as Charles Darwin 's speculation on the origin of modern life forms. However, evolutionary theory is not speculation. While Darwin is rightly credited with first articulating the theory of natural selection, his ideas built on more than a century of scientific research that came before him, and are supported by over a century and a half of research since.

• The Fixity Notion: Linnaeus

Figure 1: Cover of the 1760 edition of Systema Naturae .

Research about the origins and diversity of life proliferated in the 18th and 19th centuries. Carolus Linnaeus , a Swedish botanist and the father of modern taxonomy (see our module Taxonomy I for more information), was a devout Christian who believed in the concept of Fixity of Species , an idea based on the biblical story of creation. The Fixity of Species concept said that each species is based on an ideal form that has not changed over time. In the early stages of his career, Linnaeus traveled extensively and collected data on the structural similarities and differences between different species of plants. Noting that some very different plants had similar structures, he began to piece together his landmark work, Systema Naturae, in 1735 (Figure 1). In Systema , Linnaeus classified organisms into related groups based on similarities in their physical features. He developed a hierarchical classification system , even drawing relationships between seemingly disparate species (for example, humans, orangutans, and chimpanzees) based on the physical similarities that he observed between these organisms. Linnaeus did not explicitly discuss change in organisms or propose a reason for his hierarchy, but by grouping organisms based on physical characteristics, he suggested that species are related, unintentionally challenging the Fixity notion that each species is created in a unique, ideal form.

• The age of Earth: Leclerc and Hutton

Also in the early 1700s, Georges-Louis Leclerc, a French naturalist, and James Hutton , a Scottish geologist, began to develop new ideas about the age of the Earth. At the time, many people thought of the Earth as 6,000 years old, based on a strict interpretation of the events detailed in the Christian Old Testament by the influential Scottish Archbishop Ussher. By observing other planets and comets in the solar system , Leclerc hypothesized that Earth began as a hot, fiery ball of molten rock, mostly consisting of iron. Using the cooling rate of iron, Leclerc calculated that Earth must therefore be at least 70,000 years old in order to have reached its present temperature.

Hutton approached the same topic from a different perspective, gathering observations of the relationships between different rock formations and the rates of modern geological processes near his home in Scotland. He recognized that the relatively slow processes of erosion and sedimentation could not create all of the exposed rock layers in only a few thousand years (see our module The Rock Cycle ). Based on his extensive collection of data (just one of his many publications ran to 2,138 pages), Hutton suggested that the Earth was far older than human history – hundreds of millions of years old.

While we now know that both Leclerc and Hutton significantly underestimated the age of the Earth (by about 4 billion years), their work shattered long-held beliefs and opened a window into research on how life can change over these very long timescales.

• Fossil studies lead to the development of a theory of evolution: Cuvier

Figure 2: Illustration of an Indian elephant jaw and a mammoth jaw from Cuvier's 1796 paper.

With the age of Earth now extended by Leclerc and Hutton, more researchers began to turn their attention to studying past life. Fossils are the main way to study past life forms, and several key studies on fossils helped in the development of a theory of evolution . In 1795, Georges Cuvier began to work at the National Museum in Paris as a naturalist and anatomist. Through his work, Cuvier became interested in fossils found near Paris, which some claimed were the remains of the elephants that Hannibal rode over the Alps when he invaded Rome in 218 BCE . In studying both the fossils and living species , Cuvier documented different patterns in the dental structure and number of teeth between the fossils and modern elephants (Figure 2) (Horner, 1843). Based on these data , Cuvier hypothesized that the fossil remains were not left by Hannibal, but were from a distinct species of animal that once roamed through Europe and had gone extinct thousands of years earlier: the mammoth. The concept of species extinction had been discussed by a few individuals before Cuvier, but it was in direct opposition to the Fixity of Species concept – if every organism were based on a perfectly adapted, ideal form, how could any cease to exist? That would suggest it was no longer ideal.

While his work provided critical evidence of extinction , a key component of evolution , Cuvier was highly critical of the idea that species could change over time. As a result of his extensive studies of animal anatomy, Cuvier had developed a holistic view of organisms , stating that the

number, direction, and shape of the bones that compose each part of an animal's body are always in a necessary relation to all the other parts, in such a way that ... one can infer the whole from any one of them ...

In other words, Cuvier viewed each part of an organism as a unique, essential component of the whole organism. If one part were to change, he believed, the organism could not survive. His skepticism about the ability of organisms to change led him to criticize the whole idea of evolution , and his prominence in France as a scientist played a large role in discouraging the acceptance of the idea in the scientific community.

• Studies of invertebrates support a theory of change in species: Lamarck

Jean Baptiste Lamarck, a contemporary of Cuvier's at the National Museum in Paris, studied invertebrates like insects and worms. As Lamarck worked through the museum's large collection of invertebrates, he was impressed by the number and variety of organisms . He became convinced that organisms could, in fact, change through time, stating that

... time and favorable conditions are the two principal means which nature has employed in giving existence to all her productions. We know that for her time has no limit, and that consequently she always has it at her disposal.

This was a radical departure from both the fixity concept and Cuvier's ideas, and it built on the long timescale that geologists had recently established. Lamarck proposed that changes that occurred during an organism 's lifetime could be passed on to their offspring, suggesting, for example, that a body builder's muscles would be inherited by their children.

As it turned out, the mechanism by which Lamarck proposed that organisms change over time was wrong, and he is now often referred to disparagingly for his "inheritance of acquired characteristics" idea. Yet despite the fact that some of his ideas were discredited, Lamarck established a support for evolutionary theory that others would build on and improve.

• Rock layers as evidence for evolution: Smith

In the early 1800s, a British geologist and canal surveyor named William Smith added another component to the accumulating evidence for evolution . Smith observed that rock layers exposed in different parts of England bore similarities to one another: These layers (or strata) were arranged in a predictable order, and each layer contained distinct groups of fossils . From this series of observations , he developed a hypothesis that specific groups of animals followed one another in a definite sequence through Earth's history, and this sequence could be seen in the rock layers. Smith's hypothesis was based on his knowledge of geological principles , including the Law of Superposition.

The Law of Superposition states that sediments are deposited in a time sequence, with the oldest sediments deposited first, or at the bottom, and newer layers deposited on top. The concept was first expressed by the Persian scientist Avicenna in the 11th century, but was popularized by the Danish scientist Nicolas Steno in the 17th century. Note that the law does not state how sediments are deposited; it simply describes the relationship between the ages of deposited sediments.

Figure 3: Engraving from William Smith's 1815 monograph on identifying strata by fossils.

Smith backed up his hypothesis with extensive drawings of fossils uncovered during his research (Figure 3), thus allowing other scientists to confirm or dispute his findings. His hypothesis has, in fact, been confirmed by many other scientists and has come to be referred to as the Law of Faunal Succession. His work was critical to the formation of evolutionary theory as it not only confirmed Cuvier's work that organisms have gone extinct , but it also showed that the appearance of life does not date to the birth of the planet. Instead, the fossil record preserves a timeline of the appearance and disappearance of different organisms in the past, and in doing so offers evidence for change in organisms over time.

• The theory of evolution by natural selection: Darwin and Wallace

It was into this world that Charles Darwin entered: Linnaeus had developed a taxonomy of organisms based on their physical relationships, Leclerc and Hutton demonstrated that there was sufficient time in Earth's history for organisms to change, Cuvier showed that species of organisms have gone extinct , Lamarck proposed that organisms change over time, and Smith established a timeline of the appearance and disappearance of different organisms in the geological record .

Figure 4: Title page of the 1859 Murray edition of the Origin of Species by Charles Darwin.

Charles Darwin collected data during his work as a naturalist on the HMS Beagle starting in 1831. He took extensive notes on the geology of the places he visited; he made a major find of fossils of extinct animals in Patagonia and identified an extinct giant ground sloth named Megatherium . He experienced an earthquake in Chile that stranded beds of living mussels above water, where they would be preserved for years to come.

Perhaps most famously, he conducted extensive studies of animals on the Galápagos Islands, noting subtle differences in species of mockingbird, tortoise, and finch that were isolated on different islands with different environmental conditions. These subtle differences made the animals highly adapted to their environments .

This broad spectrum of data led Darwin to propose an idea about how organisms change "by means of natural selection" (Figure 4). But this idea was not based only on his work, it was also based on the accumulation of evidence and ideas of many others before him. Because his proposal encompassed and explained many different lines of evidence and previous work, they formed the basis of a new and robust scientific theory regarding change in organisms – the theory of evolution by natural selection .

Darwin's ideas were grounded in evidence and data so compelling that if he had not conceived them, someone else would have. In fact, someone else did. Between 1858 and 1859, Alfred Russel Wallace , a British naturalist, wrote a series of letters to Darwin that independently proposed natural selection as the means for evolutionary change. The letters were presented to the Linnean Society of London, a prominent scientific society at the time (see our module on Scientific Institutions and Societies ). This long chain of research highlights that theories are not just the work of one individual. At the same time, however, it often takes the insight and creativity of individuals to put together all of the pieces and propose a new theory . Both Darwin and Wallace were experienced naturalists who were familiar with the work of others. While all of the work leading up to 1830 contributed to the theory of evolution , Darwin's and Wallace's theory changed the way that future research was focused by presenting a comprehensive, well-substantiated set of ideas, thus becoming a fundamental theory of biological research.

• Expanding, testing, and refining scientific theories
• Genetics and evolution: Mendel and Dobzhansky

Since Darwin and Wallace first published their ideas, extensive research has tested and expanded the theory of evolution by natural selection . Darwin had no concept of genes or DNA or the mechanism by which characteristics were inherited within a species . A contemporary of Darwin's, the Austrian monk Gregor Mendel , first presented his own landmark study, Experiments in Plant Hybridization, in 1865 in which he provided the basic patterns of genetic inheritance , describing which characteristics (and evolutionary changes) can be passed on in organisms (see our Genetics I module for more information). Still, it wasn't until much later that a "gene" was defined as the heritable unit.

In 1937, the Ukrainian born geneticist Theodosius Dobzhansky published Genetics and the Origin of Species , a seminal work in which he described genes themselves and demonstrated that it is through mutations in genes that change occurs. The work defined evolution as "a change in the frequency of an allele within a gene pool" ( Dobzhansky, 1982 ). These studies and others in the field of genetics have added to Darwin's work, expanding the scope of the theory .

• Evolution under a microscope: Lenski

More recently, Dr. Richard Lenski, a scientist at Michigan State University, isolated a single Escherichia coli bacterium in 1989 as the first step of the longest running experimental test of evolutionary theory to date – a true test meant to replicate evolution and natural selection in the lab.

After the single microbe had multiplied, Lenski isolated the offspring into 12 different strains , each in their own glucose-supplied culture, predicting that the genetic make-up of each strain would change over time to become more adapted to their specific culture as predicted by evolutionary theory . These 12 lines have been nurtured for over 40,000 bacterial generations (luckily bacterial generations are much shorter than human generations) and exposed to different selective pressures such as heat , cold, antibiotics, and infection with other microorganisms. Lenski and colleagues have studied dozens of aspects of evolutionary theory with these genetically isolated populations . In 1999, they published a paper that demonstrated that random genetic mutations were common within the populations and highly diverse across different individual bacteria . However, "pivotal" mutations that are associated with beneficial changes in the group are shared by all descendants in a population and are much rarer than random mutations, as predicted by the theory of evolution by natural selection (Papadopoulos et al., 1999).

• Punctuated equilibrium: Gould and Eldredge

While established scientific theories like evolution have a wealth of research and evidence supporting them, this does not mean that they cannot be refined as new information or new perspectives on existing data become available. For example, in 1972, biologist Stephen Jay Gould and paleontologist Niles Eldredge took a fresh look at the existing data regarding the timing by which evolutionary change takes place. Gould and Eldredge did not set out to challenge the theory of evolution; rather they used it as a guiding principle and asked more specific questions to add detail and nuance to the theory. This is true of all theories in science: they provide a framework for additional research. At the time, many biologists viewed evolution as occurring gradually, causing small incremental changes in organisms at a relatively steady rate. The idea is referred to as phyletic gradualism , and is rooted in the geological concept of uniformitarianism . After reexamining the available data, Gould and Eldredge came to a different explanation, suggesting that evolution consists of long periods of stability that are punctuated by occasional instances of dramatic change – a process they called punctuated equilibrium .

Like Darwin before them, their proposal is rooted in evidence and research on evolutionary change, and has been supported by multiple lines of evidence. In fact, punctuated equilibrium is now considered its own theory in evolutionary biology. Punctuated equilibrium is not as broad of a theory as natural selection . In science, some theories are broad and overarching of many concepts, such as the theory of evolution by natural selection; others focus on concepts at a smaller, or more targeted, scale such as punctuated equilibrium. And punctuated equilibrium does not challenge or weaken the concept of natural selection; rather, it represents a change in our understanding of the timing by which change occurs in organisms , and a theory within a theory. The theory of evolution by natural selection now includes both gradualism and punctuated equilibrium to describe the rate at which change proceeds.

• Hypotheses and laws: Other scientific concepts

One of the challenges in understanding scientific terms like theory is that there is not a precise definition even within the scientific community. Some scientists debate over whether certain proposals merit designation as a hypothesis or theory , and others mistakenly use the terms interchangeably. But there are differences in these terms. A hypothesis is a proposed explanation for an observable phenomenon. Hypotheses , just like theories , are based on observations from research . For example, LeClerc did not hypothesize that Earth had cooled from a molten ball of iron as a random guess; rather, he developed this hypothesis based on his observations of information from meteorites.

A scientist often proposes a hypothesis before research confirms it as a way of predicting the outcome of study to help better define the parameters of the research. LeClerc's hypothesis allowed him to use known parameters (the cooling rate of iron) to do additional work. A key component of a formal scientific hypothesis is that it is testable and falsifiable. For example, when Richard Lenski first isolated his 12 strains of bacteria , he likely hypothesized that random mutations would cause differences to appear within a period of time in the different strains of bacteria. But when a hypothesis is generated in science, a scientist will also make an alternative hypothesis , an explanation that explains a study if the data do not support the original hypothesis. If the different strains of bacteria in Lenski's work did not diverge over the indicated period of time, perhaps the rate of mutation was slower than first thought.

So you might ask, if theories are so well supported, do they eventually become laws? The answer is no – not because they aren't well-supported, but because theories and laws are two very different things. Laws describe phenomena, often mathematically. Theories, however, explain phenomena. For example, in 1687 Isaac Newton proposed a Theory of Gravitation, describing gravity as a force of attraction between two objects. As part of this theory, Newton developed a Law of Universal Gravitation that explains how this force operates. This law states that the force of gravity between two objects is inversely proportional to the square of the distance between those objects. Newton 's Law does not explain why this is true, but it describes how gravity functions (see our Gravity: Newtonian Relationships module for more detail). In 1916, Albert Einstein developed his theory of general relativity to explain the mechanism by which gravity has its effect. Einstein's work challenges Newton's theory, and has been found after extensive testing and research to more accurately describe the phenomenon of gravity. While Einstein's work has replaced Newton's as the dominant explanation of gravity in modern science, Newton's Law of Universal Gravitation is still used as it reasonably (and more simply) describes the force of gravity under many conditions. Similarly, the Law of Faunal Succession developed by William Smith does not explain why organisms follow each other in distinct, predictable ways in the rock layers, but it accurately describes the phenomenon.

Theories, hypotheses , and laws drive scientific progress

Theories, hypotheses , and laws are not simply important components of science, they drive scientific progress. For example, evolutionary biology now stands as a distinct field of science that focuses on the origins and descent of species . Geologists now rely on plate tectonics as a conceptual model and guiding theory when they are studying processes at work in Earth's crust . And physicists refer to atomic theory when they are predicting the existence of subatomic particles yet to be discovered. This does not mean that science is "finished," or that all of the important theories have been discovered already. Like evolution , progress in science happens both gradually and in short, dramatic bursts. Both types of progress are critical for creating a robust knowledge base with data as the foundation and scientific theories giving structure to that knowledge.

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• Theories, hypotheses, and laws drive scientific progress

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“Theory” vs. “Hypothesis”: What Is The Difference?

Chances are you’ve heard of the TV show The Big Bang Theory . Lots of people love this lighthearted sitcom for its quirky characters and their relationships, but others haven’t even given the series a chance for one reason: they don’t like science and assume the show is boring.

However, it only takes a few seconds with Sheldon and Penny to disprove this assumption and realize that this theory ab0ut The Big Bang Theory is wrong—it isn’t a scientific snoozefest.

But wait: is it a theory or a  hypothesis about the show that leads people astray? And would the actual big bang theory— the one that refers to the beginning of the universe—mean the same thing as a big bang hypothesis ?

Let’s take a closer look at theory and hypothesis to nail down what they mean.

What does theory mean?

As a noun, a theory is a group of tested general propositions “commonly regarded as correct, that can be used as principles of explanation and prediction for a class of phenomena .” This is what is known as a scientific   theory , which by definition is “an understanding that is based on already tested data or results .” Einstein’s theory of relativity and the  theory of evolution are both examples of such tested propositions .

Theory is also defined as a proposed explanation you might make about your own life and observations, and it’s one “whose status is still conjectural and subject to experimentation .” For example:  I’ve got my own theories about why he’s missing his deadlines all the time.  This example refers to an idea that has not yet been proven.

There are other uses of the word theory as well.

• In this example,  theory is “a body of principles or theorems belonging to one subject.” It can be a branch of science or art that deals with its principles or methods .
• For example: when she started to follow a new parenting theory based on a trendy book, it caused a conflict with her mother, who kept offering differing opinions .

First recorded in 1590–1600, theory originates from the Late Latin theōria , which stems from the Greek theōría. Synonyms for theory include approach , assumption , doctrine , ideology , method , philosophy , speculation , thesis , and understanding .

What does hypothesis mean?

Hypothesis is a noun that means “a proposition , or set of propositions, set forth as an explanation” that describe “some specified group of phenomena.” Sounds familiar to theory , no?

But, unlike a theory , a scientific  hypothesis is made before testing is done and isn’t based on results. Instead, it is the basis for further investigation . For example: her working hypothesis is that this new drug also has an unintended effect on the heart, and she is curious what the clinical trials  will show .

Hypothesis also refers to “a proposition assumed as a premise in an argument,” or “mere assumption or guess.” For example:

• She decided to drink more water for a week to test out her hypothesis that dehydration was causing her terrible headaches.
• After a night of her spouse’s maddening snoring, she came up with the hypothesis that sleeping on his back was exacerbating the problem.

Hypothesis was first recorded around 1590–1600 and originates from the Greek word hypóthesis (“basis, supposition”). Synonyms for hypothesis include: assumption , conclusion , conjecture , guess , inference , premise , theorem , and thesis .

How to use each

Although theory in terms of science is used to express something based on extensive research and experimentation, typically in everyday life, theory is used more casually to express an educated guess.

So in casual language,  theory and hypothesis are more likely to be used interchangeably to express an idea or speculation .

In most everyday uses, theory and hypothesis convey the same meaning. For example:

• Her opinion is just a theory , of course. She’s just guessing.
• Her opinion is just a hypothesis , of course. She’s just guessing.

It’s important to remember that a scientific   theory is different. It is based on tested results that support or substantiate it, whereas a hypothesis is formed before the research.

For example:

• His  hypothesis  for the class science project is that this brand of plant food is better than the rest for helping grass grow.
• After testing his hypothesis , he developed a new theory based on the experiment results: plant food B is actually more effective than plant food A in helping grass grow.

In these examples, theory “doesn’t mean a hunch or a guess,” according to Kenneth R. Miller, a cell biologist at Brown University. “A theory is a system of explanations that ties together a whole bunch of facts. It not only explains those facts, but predicts what you ought to find from other observations and experiments.”

So if you have a concept that is based on substantiated research, it’s a theory .

But if you’re working off of an assumption that you still need to test, it’s a hypothesis .

So remember, first comes a hypothesis , then comes theory . Now who’s ready for a  Big Bang Theory marathon?

Now that you’ve theorized and hypothesized through this whole article … keep testing your judgment (Or is it judgement?). Find out the correct spelling here!

Or find out the difference between these two common issues below!

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Hypothesis vs. Theory: Understanding the Differences

“Hypothesis” and “theory” are two terms often used in science, but they have different meanings. Understanding the distinction between these two words can help us make sense of scientific explanations. In this article, we will explore the differences between “hypothesis” and “theory” in a way that is easy to understand. By the end, you’ll have a clearer grasp of these concepts and be able to use them confidently in scientific discussions.

Hypothesis vs. Theory

• A  hypothesis  is a preliminary assumption to be tested.
• A  theory  is a well-supported explanation for a broad range of phenomena.

Hypothesis vs. Theory: The Definition

What does hypothesis mean.

A hypothesis is a proposed explanation for a phenomenon or a scientific question that can be tested through experimentation or observation. It is an essential part of the scientific method, which involves formulating a hypothesis, conducting experiments to test it, and analyzing the results to draw conclusions.

In scientific research, a hypothesis serves as a tentative solution to a problem or a preliminary explanation for an observed phenomenon. It is based on existing knowledge and is formulated to be tested and potentially refuted through empirical evidence. A well-constructed hypothesis is specific, testable, and falsifiable, meaning that it can be proven false through experimentation or observation.

• Example of a hypothesis : “If a person consumes more vitamin C, then their immune system will be stronger and they will have a lower likelihood of catching a cold.”

What Does Theory Mean?

A theory is a well-substantiated explanation of some aspect of the natural world that is based on a body of evidence, observations, and experimentation. In the scientific context, a theory is more than just a guess or a hypothesis; it is a comprehensive framework that has been rigorously tested and supported by a substantial amount of empirical data.

Scientific theories are developed through the scientific method, which involves formulating hypotheses, conducting experiments, and analyzing the results. As evidence accumulates and supports a particular explanation, it may be elevated to the status of a theory. Importantly, scientific theories are not static or unchangeable; they are subject to modification or even rejection in light of new evidence or more comprehensive explanations.

• Example of a theory: The theory of evolution, which explains how species change over time through the process of natural selection.

Hypothesis vs. Theory: Usage

You employ  hypotheses  during the early stages of research to develop experiments. For instance, you might hypothesize that a plant given more sunlight will grow faster.

A  theory , like the Theory of Evolution, summarizes a group of tested hypotheses and facts to explain a complex set of patterns and behaviors.

For a better understanding of the differences between the two terms, let’s take a look at the table below:

Tips to Remember the Differences

• Think of a  hypothesis  as a  “hunch”  to be tested.
• View a  theory  as a  “tapestry”  of well-tested ideas.
• Use the phrase  “hypothesis for testing”  and  “theory for explaining”  to keep them distinct in your mind.

Hypothesis vs. Theory: Examples

Example sentences using hypothesis.

• She formulated a  hypothesis  to explain the observed pattern in the data.
• The researchers tested their  hypothesis  through a series of carefully controlled experiments.
• The  hypothesis  proposed by the scientist led to a new understanding of the chemical reaction.
• It is essential to develop a clear and testable  hypothesis  before conducting the research.
• The  hypothesis  was supported by the experimental results, providing valuable insights into the phenomenon.

Example Sentences Using Theory

• Einstein ‘s  theory of relativity has fundamentally altered our understanding of space and time.
• Darwin’s theory of natural selection provides a framework for understanding the evolution of species.
• The germ theory of disease is fundamental in developing medical hygiene practices.
• The  Big Bang theory is widely accepted as the leading explanation for the origin of the universe.
• The  kinetic molecular theory  explains the behavior of gases, including their volume and temperature relationships.

Related Confused Words

Hypothesis vs thesis.

A hypothesis is a specific, testable prediction that is proposed before conducting a research study, while a thesis is a statement or theory put forward to be maintained or proved. In essence, a hypothesis is a tentative assumption made in order to draw out and test its logical or empirical consequences, while a thesis is a proposition that is maintained by argument.

Both play distinct roles in the scientific and academic realms, with hypotheses guiding research and theses forming the central point of an argument or discussion.

Theory vs. Law

The primary difference between a scientific theory and a scientific law lies in their scope and function. A scientific theory is a well-substantiated explanation of some aspect of the natural world that is based on a body of evidence and has undergone rigorous testing and validation. In contrast, a scientific law describes a concise statement or mathematical equation that summarizes a wide variety of observations and experiments, often expressing a fundamental principle of nature.

While a theory provides an overarching framework for understanding a phenomenon, a law describes a specific, observable relationship. Both theory and law are vital components of scientific understanding, with theories offering explanations and laws providing concise descriptions of natural phenomena.

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Hypothesis, Model, Theory, and Law

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In common usage, the words hypothesis, model, theory, and law have different interpretations and are at times used without precision, but in science they have very exact meanings.

Perhaps the most difficult and intriguing step is the development of a specific, testable hypothesis. A useful hypothesis enables predictions by applying deductive reasoning, often in the form of mathematical analysis. It is a limited statement regarding the cause and effect in a specific situation, which can be tested by experimentation and observation or by statistical analysis of the probabilities from the data obtained. The outcome of the test hypothesis should be currently unknown, so that the results can provide useful data regarding the validity of the hypothesis.

Sometimes a hypothesis is developed that must wait for new knowledge or technology to be testable. The concept of atoms was proposed by the ancient Greeks , who had no means of testing it. Centuries later, when more knowledge became available, the hypothesis gained support and was eventually accepted by the scientific community, though it has had to be amended many times over the year. Atoms are not indivisible, as the Greeks supposed.

A model is used for situations when it is known that the hypothesis has a limitation on its validity. The Bohr model of the atom , for example, depicts electrons circling the atomic nucleus in a fashion similar to planets in the solar system. This model is useful in determining the energies of the quantum states of the electron in the simple hydrogen atom, but it is by no means represents the true nature of the atom. Scientists (and science students) often use such idealized models  to get an initial grasp on analyzing complex situations.

Theory and Law

A scientific theory or law represents a hypothesis (or group of related hypotheses) which has been confirmed through repeated testing, almost always conducted over a span of many years. Generally, a theory is an explanation for a set of related phenomena, like the theory of evolution or the big bang theory . 

The word "law" is often invoked in reference to a specific mathematical equation that relates the different elements within a theory. Pascal's Law refers an equation that describes differences in pressure based on height. In the overall theory of universal gravitation developed by Sir Isaac Newton , the key equation that describes the gravitational attraction between two objects is called the law of gravity .

These days, physicists rarely apply the word "law" to their ideas. In part, this is because so many of the previous "laws of nature" were found to be not so much laws as guidelines, that work well within certain parameters but not within others.

Scientific Paradigms

Once a scientific theory is established, it is very hard to get the scientific community to discard it. In physics, the concept of ether as a medium for light wave transmission ran into serious opposition in the late 1800s, but it was not disregarded until the early 1900s, when Albert Einstein proposed alternate explanations for the wave nature of light that did not rely upon a medium for transmission.

The science philosopher Thomas Kuhn developed the term scientific paradigm to explain the working set of theories under which science operates. He did extensive work on the scientific revolutions that take place when one paradigm is overturned in favor of a new set of theories. His work suggests that the very nature of science changes when these paradigms are significantly different. The nature of physics prior to relativity and quantum mechanics is fundamentally different from that after their discovery, just as biology prior to Darwin’s Theory of Evolution is fundamentally different from the biology that followed it. The very nature of the inquiry changes.

One consequence of the scientific method is to try to maintain consistency in the inquiry when these revolutions occur and to avoid attempts to overthrow existing paradigms on ideological grounds.

Occam’s Razor

One principle of note in regards to the scientific method is Occam’s Razor (alternately spelled Ockham's Razor), which is named after the 14th century English logician and Franciscan friar William of Ockham. Occam did not create the concept—the work of Thomas Aquinas and even Aristotle referred to some form of it. The name was first attributed to him (to our knowledge) in the 1800s, indicating that he must have espoused the philosophy enough that his name became associated with it.

The Razor is often stated in Latin as:

entia non sunt multiplicanda praeter necessitatem

or, translated to English:

entities should not be multiplied beyond necessity

Occam's Razor indicates that the most simple explanation that fits the available data is the one which is preferable. Assuming that two hypotheses presented have equal predictive power, the one which makes the fewest assumptions and hypothetical entities takes precedence. This appeal to simplicity has been adopted by most of science, and is invoked in this popular quote by Albert Einstein:

Everything should be made as simple as possible, but not simpler.

It is significant to note that Occam's Razor does not prove that the simpler hypothesis is, indeed, the true explanation of how nature behaves. Scientific principles should be as simple as possible, but that's no proof that nature itself is simple.

However, it is generally the case that when a more complex system is at work there is some element of the evidence which doesn't fit the simpler hypothesis, so Occam's Razor is rarely wrong as it deals only with hypotheses of purely equal predictive power. The predictive power is more important than the simplicity.

Edited by Anne Marie Helmenstine, Ph.D.

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• What Is Model-Dependent Realism?

Why Fans Think Tom Bombadil Is God: Lord of the Rings Theory Explained

By Apoorv Rastogi

The curious character of Tom Bombadil has finally made his on-screen debut, doing so in the second season of The Rings of Power . Despite his significance in J.R.R. Tolkien’s lore, the eternal being was notably absent from Peter Jackson’s The Lord of The Rings trilogy. While the mysterious entity has seemingly roamed Earth since the dawn of humanity, details about his origins have remained uncertain. Nevertheless, LOTR fans have hypothesized for a long time that Tom Bombadil is the God of Tolkien’s expansive universe. But how credible are these speculations?

Here is a complete breakdown of the theory that relates Tom Bombadil to God himself.

Is Tom Bombadil God in The Lord of the Rings?

To this date, no official piece of content by J.R.R. Tolkien has confirmed Tom Bombadil as the God of his universe. Nevertheless, multiple signs in the original lore do appear to hint at the possibility of this proposition being true.

While there are doubts regarding Bombadil’s identity as The Almighty, the Tolkien world is indeed presided over by a God referred to as Eru Iluvatar. The primaeval being is responsible for creating all life alongside his first children, the Ainur. Iluvatar, as per his stature, fundamentally refrains from meddling with the day-to-day proceedings of living creatures. Instead, the divine entity only acts on certain occasions spread throughout Tolkien’s history.

Similar to Iluvatar, Tom Bombadil is also a mysterious being who shares a profound relationship with nature. The character does not interfere heavily with the events of the main story but still manages to influence it through his actions. He indirectly helps Frodo on his journey, mirroring Eru’s disjointed association with Middle-earth.

Meanwhile, Bombadil describes himself as the eldest who has seen the first raindrop, further solidifying his position as God. His claims are somewhat echoed by the ancient elf Elrond, who calls him fatherless. Addressing the glaring doubt, The Rings of Power showrunners recently shared their thoughts on the debate.

While talking to The Hollywood Reporter, J. D. Payne and Patrick McKay stated that they are well aware of the theory that connects Tom Bombadil to God. However, they also chose to share Tolkien’s take on the topic and shied away from giving a conclusive answer.

As such, the nature of Tom Bombadil’s character remains up for debate among fans to this date.

Apoorv is an SEO Contributing Writer for ComingSoon. A dedicated cinephile inside and out, Apoorv's passion for content creation motivated him to ditch the software sector in favour of pursuing a career in the entertainment industry. He is also an avid sports enthusiast, with football topping his favorites list.

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Probability Theory II

Stochastic Calculus

• © 2024
• Andrea Pascucci   ORCID: https://orcid.org/0000-0001-8837-5568 0

Dipartimento di Matematica, Alma Mater Studiorum – Università di Bologna, Bologna, Italy

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• Rigorous, comprehensive, and self-contained presentation
• Written clearly to make complex mathematics accessible
• Comprehensive overview of stochastic process theory with brief mentions of its most significant applications

Part of the book series: UNITEXT (UNITEXT, volume 166)

Part of the book sub series: La Matematica per il 3+2 (UNITEXTMAT)

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About this book

This book offers a modern approach to the theory of continuous-time stochastic processes and stochastic calculus. The content is treated rigorously, comprehensively, and independently. In the first part, the theory of Markov processes and martingales is introduced, with a focus on Brownian motion and the Poisson process. Subsequently, the theory of stochastic integration for continuous semimartingales was developed. A substantial portion is dedicated to stochastic differential equations, the main results of solvability and uniqueness in weak and strong sense, linear stochastic equations, and their relation to deterministic partial differential equations. Each chapter is accompanied by numerous examples. This text stems from over twenty years of teaching experience in stochastic processes and calculus within master's degrees in mathematics, quantitative finance, and postgraduate courses in mathematics for applications and mathematical finance at the University of Bologna. The book provides material for at least two semester-long courses in scientific studies (Mathematics, Physics, Engineering, Statistics, Economics, etc.) and aims to provide a solid background for those interested in the development of stochastic calculus theory and its applications. This text completes the journey started with the first volume of Probability Theory I - Random Variables and Distributions, through a selection of advanced classic topics in stochastic analysis.

• Stochastic differential equations
• Brownian motion
• Ito integral
• Markov process
• Stochastic calculus
• Ito formula
• Stochastic process

Table of contents (20 chapters)

Front matter, stochastic processes.

Andrea Pascucci

Markov Processes

Continuous processes, brownian motion, poisson process, stopping times, strong markov property, continuous martingales, theory of variation, stochastic integral, itô’s formula, multidimensional stochastic calculus, changes of measure and martingale representation, stochastic differential equations, feynman-kac formulas, linear equations, strong solutions, weak solutions, complements, authors and affiliations, about the author.

Andrea Pascucci is a professor of Probability and Mathematical Statistics at the Alma Mater Studiorum – University of Bologna. His research activity encompasses various aspects of the theory of stochastic differential equations for diffusions and jump processes, degenerate partial differential equations, and their applications to mathematical finance. He has authored 6 books and over 80 scientific articles on the following topics: linear and nonlinear Kolmogorov-Fokker-Planck equations; regularity and asymptotic estimates of transition densities for multidimensional diffusions and jump processes; free boundary problems, optimal stopping, and applications to American-style financial derivatives; Asian options and volatility models. He has been invited as a speaker at more than 40 international conferences. He serves as an editor for the Journal of Computational Finance and is the director of a postgraduate program in Mathematical Finance at the University of Bologna.

Bibliographic Information

Book Title : Probability Theory II

Book Subtitle : Stochastic Calculus

Authors : Andrea Pascucci

Series Title : UNITEXT

DOI : https://doi.org/10.1007/978-3-031-63193-1

Publisher : Springer Cham

eBook Packages : Mathematics and Statistics , Mathematics and Statistics (R0)

Copyright Information : The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2024

Softcover ISBN : 978-3-031-63192-4 Due: 04 October 2024

eBook ISBN : 978-3-031-63193-1 Published: 02 September 2024

Series ISSN : 2038-5714

Series E-ISSN : 2532-3318

Edition Number : 1

Number of Pages : XIX, 426

Number of Illustrations : 4 b/w illustrations, 14 illustrations in colour

Topics : Probability Theory and Stochastic Processes , Applications of Mathematics

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1st Edition

The Political Theory of Liberal Socialism

Description.

McManus presents a comprehensive guide to the liberal socialist tradition, stretching from Mary Wollstonecraft and Thomas Paine through John Stuart Mill to Irving Howe, John Rawls and Charles Mills.

Providing a comprehensive critical genealogy of liberal socialism from a sympathetic but critical standpoint, McManus traces its core to the Revolutionary period that catalysed major divisions in liberal political theory to the French Revolution that saw the emergence of writers like Mary Wollstonecraft and Thomas Paine who argued that liberal principles could only be inadequately instantiated in a society with high levels of material and social inequality to John Stuart Mill, the first major thinker who declared himself a liberal and a socialist and who made major contributions to both traditions through his efforts to synthesize and conciliate them. McManus argues for liberal socialism as a political theory which could truly secure equality and liberty for all.

An essential book on the tradition of liberal socialism for students, researchers and scholars of political science and humanities.

Table of Contents

Introduction: Retrieving Liberal Socialism 1. What is Liberal Socialism? Part I: The Origins of Liberal Socialism  2. Liberty, Equality and Fraternity  3. Thomas Paine’s Denaturalization of Inequality  4. Mary Wollstonecraft and the Egalitarian Rights of Man and Woman  Part II: The Maturation of Liberal Socialism  5. John Stuart Mill-The First Liberal Socialist  6. Karl Marx’s Critique of Liberalism 7. Ethical Socialism and Social Democratic Reformism  8. C.B Macpherson’s Critique of “Possessive Individualism”  9. John Rawls’ Just Society 10. On Racial and Black Radical Liberalism  Part III: The Future of Liberal Socialism 11. Chantal Mouffe, Norberto Bobbio, and Axel Honneth-Agonistic Liberal Socialism and the Dialectics of Recognition 12. A Future For Liberal Socialism?

Matthew McManus is a Lecturer in Political Science at the University of Michigan, USA. He is the author of The Political Right and Equality (Routledge) and A Critical Legal Examination of Liberalism and Liberal Rights amongst other books.

Critics' Reviews

Matt McManus has been an intellectual leader in the revival of liberal socialism, and in this absorbing survey he shows how strong a basis there is for that position in the past, without disguising how much work it will take to redeem and reinvent it for our future. Indispensable and magisterial. Samuel Moyn , author of Liberalism against Itself: Cold War Intellectuals and the Making of Our Times Liberal socialism? That’s an oxymoron! Absolutely not, says Matt McManus in his brilliant new book. His inspiring and positive vision is exactly what we liberals need to get our mojo back.   Alexandre Lefebvre , Professor of Politics and Philosophy, The University of Sydney, Australia Matt McManus is a penetrating thinker who recognizes that many of the things our culture war insists are “opposites” are, in fact, nothing of the kind. In an era in which millions have dubbed both liberalism and socialism dead, The Political Theory of Liberal Socialism, offers a retrieval of both traditions. Ranging over canonical liberal and socialist thinkers with ease—from Thomas Paine and John Rawls to Karl Marx and many others—McManus shows how in order to return from their current crises of credibility each ideological tradition must learn from the other. The entire book is an effort at fusing horizons and opening ideological possibilities that have been forgotten. Where the political imagination in North Atlantic societies has grown brittle, narrow, and simplistic, McManus seeks to break it wide open once more. Jason Blakely, author of Lost in Ideology and We Built Reality The Political Theory of Liberal Socialism traces the intellectual roots of a distinct political theory, highlighting its advantages for modern liberals as an ideology for the future (as well as the challenges it may face in theory and in practice). Matt McManus provides a fascinating survey, retrieving the history of this often-overlooked philosophical stance, establishing it as a genuine position (though diverse and sometimes disparate), and critically exploring its positives and possibilities. A must-read for all left-leaning liberals and/or socialists committed to individual flourishing who are looking for an intellectual tradition, providing a stimulating resource for recasting contemporary debates and forming radical policy proposals for the future. Helen McCabe , Associate Professor in Political Theory, University of Nottingham, UK So many important works of political theory feel so distant from our moment, but this essential text from Matthew McManus is a welcomed exception. American leftism needs its footing in the scrambled ideological landscape of the 21st century and McManus offers an intellectual bridge between two traditions that are often set in opposition to each other. A must-read for anyone concerned with building a just and compassionate world in the ashes of neoliberalism. Sean Illing , host of The Gray Area In mining a rich and often underappreciated vein of political theory, this book offers a critical and engaging survey of the various ways an important progressive philosophical tradition has sought to reconcile abiding questions of class, community, freedom, and democracy. Part intellectual history, part exercise in retrieval, it will be of interest to anyone keen to explore the points of contact — both potential and established — between a humanistic liberalism and an egalitarian socialism.  Luke Savage , Author of The Dead Center and Columnist at Jacobin Magazine Liberalism and socialism are often held to be in opposition. And yet, as Matt McManus shows in this timely and important book, there is a rich line of thinkers who have sought to - and succeeded in - reconciling these two traditions. In bringing the best of these ideas together for the first time, he has not only done a great service to intellectual history, but assembled a powerful resource for developing the truly emancipatory politics that we so urgently need. Daniel Chandler , London School of Economics and Political Science, UK

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'Too many gaps': Defence pokes holes in Crown's theory at Kane Carter murder trial

A defence lawyer for the man accused of shooting and killing an innocent teenager and a rival gang member in January of 2018 says the Crown failed to prove beyond a reasonable doubt that his client was the second gunman who fired the fatal shots.

“There’s simply too many gaps in the evidence, gaps in time, gaps in people’s memories,” said Richard Fowler.

His client, 28-year-old Kane Carter, is charged with the second-degree murders of 15-year-old Alfred Wong – an innocent passerby – and 23-year-old Kevin Whiteside, an alleged gang member.

The Crown’s theory is that on the evening of Jan. 13, 2018, Carter was the lone occupant of a burgundy Pontiac Montana van parked south of the intersection of Broadway and Ontario Street. He was there with the intent to protect his associate Matthew Navas-Rivas, who was at Indochine restaurant.

Prosecutors say Carter was working in a "middle management" role for a drug operation Navas-Rivas was running.

The Crown says as Navas-Rivas and his girlfriend left the restaurant, Whiteside opened fire at around 9:16 p.m. shooting several rounds at them. Prosecutors believe that’s when Carter, from the van, fired at Whiteside, killing both him and Wong, who was riding in the back seat of his parents' car as they drove along Broadway.

Fowler brought up how there was no evidence that Navas-Rivas knew there was a target on his back, and that phone records showed that there were no texts or calls made between him and Carter in the hours leading up to the shootings.

“If this motive for Mr. Carter to be there is to protect Mr. Navas-Rivas, Mr. Navas-Rivas must have known for some need to be protected,” said Fowler. “There’s no evidence of that at all."

A former customer turned worker for the drug-dealing operation, Jackson Riley, testified during the trial that a van of the same make and model was used for drug deliveries.

The defence has acknowledged that the drug-dealing van and the van seen at the crime scene are, indeed, the same vehicle.

Riley testified that on the night of shootings, he was out driving the van when Carter called him at around 7:45 p.m., urgently telling him to bring the vehicle back to the Seymour Street condo building where the drug operation was based.

Riley said Carter departed in the van some time just after 8 p.m.

Video then shows the van parking on Ontario Street at around 8:30 p.m.

Fowler says there would have been plenty of time for Carter to drop the van off to someone else.

“There are multiple gaps in time,” he said.

Fowler also mentioned that the three bullet casings later found in the van were linked to a shooting in September of 2017 in Vancouver, while Carter was living in Ontario at that time.

“There’s actually no evidence before you that Mr. Carter had access to the type of gun likely used in these killings,” he said.

Supreme Court Justice Catherine Wedge is expected to charge the jury on Friday morning, before deliberations will begin.

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Hanover’s police chief is responding to community concerns about a recent arrest at a Hanover school.

Waterloo, Ont. tech company blacklisted by U.S. Commerce Department over surveillance, spyware allegations

A Waterloo, Ont. tech company is in hot water for allegedly providing technology that can be used for mass surveillance and censorship.

Ontario's first domestic case of human rabies since 1967 confirmed in Brant County

An Ontario resident remains in hospital after testing positive for rabies.

Northern Ontario

Sudbury opp officer pleads guilty to stealing evidence during moose hunt investigation.

A veteran staff sergeant with the Ontario Provincial Police in Sudbury has been sentenced for stealing two items from a First Nations man and hiding what he did while his fellow officers searched for them.

Average of one impaired-related charge per day in Sudbury

Greater Sudbury Police Service say nine drivers were charged with impaired-related offences over the Labour Day long weekend.

Dispute over unrecognized Inuit group halts major conference for Canadian North

A 16-year-old biennial event aimed at fostering business in the country's eastern Arctic and northern regions has been cancelled indefinitely as a dispute unfolds between Inuit in Canada and a Labrador group claiming to share their heritage.

Cow cuddling: Why a Newfoundland farm is offering quality time with these 'gentle creatures'

Jim Lester’s farm hopped on the cow-cuddling trend in early August, and his time slots have been pretty well sold out ever since.

Newly reinstated Newfoundland cod fishery temporarily paused as landings hit limit

The federal government has temporarily paused parts of the newly reinstated commercial northern cod fishery off the east coast of Newfoundland as landings approach the seasonal limit.

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