difference between hypothesis and theory quizlet

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

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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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“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!

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Scientific Hypothesis, Model, Theory, and Law

Understanding the Difference Between Basic Scientific Terms

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Words have precise meanings in science. For example, "theory," "law," and "hypothesis" don't all mean the same thing. Outside of science, you might say something is "just a theory," meaning it's a supposition that may or may not be true. In science, however, a theory is an explanation that generally is accepted to be true. Here's a closer look at these important, commonly misused terms.

A hypothesis is an educated guess, based on observation. It's a prediction of cause and effect. Usually, a hypothesis can be supported or refuted through experimentation or more observation. A hypothesis can be disproven but not proven to be true.

Example: If you see no difference in the cleaning ability of various laundry detergents, you might hypothesize that cleaning effectiveness is not affected by which detergent you use. This hypothesis can be disproven if you observe a stain is removed by one detergent and not another. On the other hand, you cannot prove the hypothesis. Even if you never see a difference in the cleanliness of your clothes after trying 1,000 detergents, there might be one more you haven't tried that could be different.

Scientists often construct models to help explain complex concepts. These can be physical models like a model volcano or atom  or conceptual models like predictive weather algorithms. A model doesn't contain all the details of the real deal, but it should include observations known to be valid.

Example: The  Bohr model shows electrons orbiting the atomic nucleus, much the same way as the way planets revolve around the sun. In reality, the movement of electrons is complicated but the model makes it clear that protons and neutrons form a nucleus and electrons tend to move around outside the nucleus.

A scientific theory summarizes a hypothesis or group of hypotheses that have been supported with repeated testing. A theory is valid as long as there is no evidence to dispute it. Therefore, theories can be disproven. Basically, if evidence accumulates to support a hypothesis, then the hypothesis can become accepted as a good explanation of a phenomenon. One definition of a theory is to say that it's an accepted hypothesis.

Example: It is known that on June 30, 1908, in Tunguska, Siberia, there was an explosion equivalent to the detonation of about 15 million tons of TNT. Many hypotheses have been proposed for what caused the explosion. It was theorized that the explosion was caused by a natural extraterrestrial phenomenon , and was not caused by man. Is this theory a fact? No. The event is a recorded fact. Is this theory, generally accepted to be true, based on evidence to-date? Yes. Can this theory be shown to be false and be discarded? Yes.

A scientific law generalizes a body of observations. At the time it's made, no exceptions have been found to a law. Scientific laws explain things but they do not describe them. One way to tell a law and a theory apart is to ask if the description gives you the means to explain "why." The word "law" is used less and less in science, as many laws are only true under limited circumstances.

Example: Consider Newton's Law of Gravity . Newton could use this law to predict the behavior of a dropped object but he couldn't explain why it happened.

As you can see, there is no "proof" or absolute "truth" in science. The closest we get are facts, which are indisputable observations. Note, however, if you define proof as arriving at a logical conclusion, based on the evidence, then there is "proof" in science. Some work under the definition that to prove something implies it can never be wrong, which is different. If you're asked to define the terms hypothesis, theory, and law, keep in mind the definitions of proof and of these words can vary slightly depending on the scientific discipline. What's important is to realize they don't all mean the same thing and cannot be used interchangeably.

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Know the Differences & Comparisons

Difference Between Hypothesis and Theory

The term ‘hypothesis’ is often contrasted with the term theory which implies an idea, typically proven, which aims at explaining facts and events. Both hypothesis and theory are important components of developing an approach, but these are not same. There exist a fine line of difference between hypothesis and theory, discussed in this article, have a look.

Content: Hypothesis Vs Theory

Comparison chart, definition of hypothesis.

An unproven statement or a mere assumption to be proved or disproved, about a factor, on which the researcher is interested, is called a hypothesis. It is a tentative statement, which is concerned with the relationship between two or more phenomena, as specified by the theoretical framework. The hypothesis has to go through a test, to determine its validity.

In other words, the hypothesis is a predictive statement, which can be objectively verified and tested through scientific methods, and relates the independent factor to the dependent one. To a researcher, a hypothesis is more like a question which he intends to resolve. The salient features of hypothesis are:

• It must be clear and precise or else the reliability of the inferences drawn will be questioned.
• It can be put to the test.
• If the hypothesis is relational, it should state the relationship between independent and dependent variables.
• The hypothesis should be open and responsive to testing within the stipulated time.
• It should be limited in scope and must be clearly defined.

Definition of Theory

An idea or a broad range of ideas that are assumed to be true, which aims at explaining cause and effect relationship between multiple observed phenomena. It is based on hypothesis, which after a thorough analysis and continuous testing and confirmation through observation and experiments, becomes a theory. As it is backed by evidence, it is scientifically proven.

Just like hypothesis, theories can also be accepted or rejected. As more and more information is gathered on the subject, theories are modified accordingly, to increase the accuracy of prediction over time.

Key Differences Between Hypothesis and Theory

The points given below are vital, so far as the difference between hypothesis and theory is concerned:

• Hypothesis refers to a supposition, based on few pieces of evidence, as an inception of further research or investigation. A theory is a well-affirmed explanation of natural phenomena, which is frequently validated through experimentation and observation.
• While the hypothesis is based on a little amount of data, the theory is based on a wide set of data.
• The hypothesis is an unproven statement; that can be tested. On the other hand, the theory is a scientifically tested and proven explanation of fact or event.
• Hypothesis relies on suggestions, prediction, possibility or projects whereas a theory is supported by evidence and is verified.
• The hypothesis may or may not be proved true, so the result is uncertain. On the contrary, the theory is one, that is assumed to be true and so its result is certain.
• Hypothesis and theory are two levels of the scientific method, i.e. theory follows hypothesis and the basis for research is hypothesis whose outcome is a theory.

Both hypothesis and theory are testable and falsifiable. When a hypothesis is proved true, by passing all critical tests and analysis, it becomes a theory. So, the hypothesis is very different from theory, as the former is something unproven but the latter is a proven and tested statement.

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BELLENS MOTEBEJANE says

July 15, 2019 at 2:31 pm

AMAIZING !WHAT ARE THE DIFFERENCE BETWEEN THEORY AND LAW?

February 17, 2022 at 3:47 am

Thanks, I’m finally clear on this for the first time in my life of 65 years

Curtis Le Gendre says

September 14, 2022 at 8:02 am

Great Information

Kenneth says

November 19, 2022 at 2:10 am

I was looking for some takes on this topic, and I found your article quite informative. It has given me a fresh perspective on the topic tackled. Thanks!

Stefanie Banis says

February 9, 2024 at 6:35 pm

Very informative! Thank you! I understand the difference much better now!

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1.6: Hypothesis, Theories, and Laws

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  Learning Objectives

• Describe the difference between hypothesis and theory as scientific terms.
• Describe the difference between a theory and scientific law.

Although many have taken science classes throughout the course of their studies, people often have incorrect or misleading ideas about some of the most important and basic principles in science. Most students have heard of hypotheses, theories, and laws, but what do these terms really mean? Prior to reading this section, consider what you have learned about these terms before. What do these terms mean to you? What do you read that contradicts or supports what you thought?

What is a Fact?

A fact is a basic statement established by experiment or observation. All facts are true under the specific conditions of the observation.

What is a Hypothesis?

One of the most common terms used in science classes is a "hypothesis". The word can have many different definitions, depending on the context in which it is being used:

• An educated guess: a scientific hypothesis provides a suggested solution based on evidence.
• Prediction: if you have ever carried out a science experiment, you probably made this type of hypothesis when you predicted the outcome of your experiment.
• Tentative or proposed explanation: hypotheses can be suggestions about why something is observed. In order for it to be scientific, however, a scientist must be able to test the explanation to see if it works and if it is able to correctly predict what will happen in a situation. For example, "if my hypothesis is correct, we should see ___ result when we perform ___ test."

A hypothesis is very tentative; it can be easily changed.

What is a Theory?

The United States National Academy of Sciences describes what a theory is as follows:

"Some scientific explanations are so well established that no new evidence is likely to alter them. The explanation becomes a scientific theory. In everyday language a theory means a hunch or speculation. Not so in science. In science, the word theory refers to a comprehensive explanation of an important feature of nature supported by facts gathered over time. Theories also allow scientists to make predictions about as yet unobserved phenomena."

"A scientific theory is a well-substantiated explanation of some aspect of the natural world, based on a body of facts that have been repeatedly confirmed through observation and experimentation. Such fact-supported theories are not "guesses" but reliable accounts of the real world. The theory of biological evolution is more than "just a theory." It is as factual an explanation of the universe as the atomic theory of matter (stating that everything is made of atoms) or the germ theory of disease (which states that many diseases are caused by germs). Our understanding of gravity is still a work in progress. But the phenomenon of gravity, like evolution, is an accepted fact.

Note some key features of theories that are important to understand from this description:

• Theories are explanations of natural phenomena. They aren't predictions (although we may use theories to make predictions). They are explanations as to why we observe something.
• Theories aren't likely to change. They have a large amount of support and are able to satisfactorily explain numerous observations. Theories can, indeed, be facts. Theories can change, but it is a long and difficult process. In order for a theory to change, there must be many observations or pieces of evidence that the theory cannot explain.
• Theories are not guesses. The phrase "just a theory" has no room in science. To be a scientific theory carries a lot of weight; it is not just one person's idea about something

Theories aren't likely to change.

What is a Law?

Scientific laws are similar to scientific theories in that they are principles that can be used to predict the behavior of the natural world. Both scientific laws and scientific theories are typically well-supported by observations and/or experimental evidence. Usually scientific laws refer to rules for how nature will behave under certain conditions, frequently written as an equation. Scientific theories are more overarching explanations of how nature works and why it exhibits certain characteristics. As a comparison, theories explain why we observe what we do and laws describe what happens.

For example, around the year 1800, Jacques Charles and other scientists were working with gases to, among other reasons, improve the design of the hot air balloon. These scientists found, after many, many tests, that certain patterns existed in the observations on gas behavior. If the temperature of the gas is increased, the volume of the gas increased. This is known as a natural law. A law is a relationship that exists between variables in a group of data. Laws describe the patterns we see in large amounts of data, but do not describe why the patterns exist.

What is a Belief?

A belief is a statement that is not scientifically provable. Beliefs may or may not be incorrect; they just are outside the realm of science to explore.

Laws vs. Theories

A common misconception is that scientific theories are rudimentary ideas that will eventually graduate into scientific laws when enough data and evidence has accumulated. A theory does not change into a scientific law with the accumulation of new or better evidence. Remember, theories are explanations and laws are patterns we see in large amounts of data, frequently written as an equation. A theory will always remain a theory; a law will always remain a law.

Video \(\PageIndex{1}\): What’s the difference between a scientific law and theory?

• A hypothesis is a tentative explanation that can be tested by further investigation.
• A theory is a well-supported explanation of observations.
• A scientific law is a statement that summarizes the relationship between variables.
• An experiment is a controlled method of testing a hypothesis.

Contributions & Attributions

Marisa Alviar-Agnew  ( Sacramento City College )

Henry Agnew (UC Davis)

What is a scientific theory?

A scientific theory is based on careful examination of facts.

• The process
• Good theory characteristics

The difference between theories, facts and laws

Additional resources, bibliography.

A scientific theory is a structured explanation to explain a group of facts or phenomena in the natural world that often incorporates a scientific hypothesis and scientific laws . The scientific definition of a theory contrasts with the definition most people use in casual language.

"The way that scientists use the word 'theory' is a little different than how it is commonly used in the lay public," said Jaime Tanner, a professor of biology at Emerson College in Boston. "Most people use the word 'theory' to mean an idea or hunch that someone has, but in science the word 'theory' refers to the way that we interpret facts."

Related: 5 sci-fi concepts that are possible (in theory)

The process of becoming a scientific theory

Every scientific theory relies on the scientific method . A scientist may make an observation and devise a hypothesis to explain that observation, then design an experiment to test that hypothesis. If the hypothesis is shown to be incorrect, the scientist will develop a new hypothesis and begin the process again. If the hypothesis is supported by the results of the experiment, it will go on to be tested again. If the hypothesis isn't disproven or surpassed by a better explanation, the scientist may incorporate it into a larger theory that helps to explain the observed phenomenon and relates it to other phenomena, according to the Field Museum . 

A scientific theory is not the end result of the scientific method; theories can be proven or rejected, just like hypotheses . And theories are continually improved or modified as more information is gathered, so that the accuracy of the prediction becomes greater over time.

Theories are foundations for furthering scientific knowledge and for putting the information gathered to practical use. Scientists use theories to develop inventions or find a cure for a disease.

Furthermore, a scientific theory is the framework for observations and facts, Tanner said. Theories may change, or the way that they are interpreted may change, but the facts themselves don't change. Tanner likens theories to a basket in which scientists keep facts and observations that they find. The shape of that basket may change as the scientists learn more and include more facts. "For example, we have ample evidence of traits in populations becoming more or less common over time (evolution), so evolution is a fact, but the overarching theories about evolution, the way that we think all of the facts go together might change as new observations of evolution are made," Tanner told Live Science.

Characteristics of a good theory

The University of California, Berkeley , defines a theory as "a broad, natural explanation for a wide range of phenomena. Theories are concise, coherent, systematic, predictive, and broadly applicable, often integrating and generalizing many hypotheses." 

According to Columbia University emeritus professor of philosophy Philip Kitcher, a good scientific theory has three characteristics. First, it has unity, which means it consists of a limited number of problem-solving strategies that can be applied to a wide range of scientific circumstances. Second, a good scientific theory leads to new questions and new areas of research. This means that a theory doesn't need to explain everything in order to be useful. And finally, a good theory is formed from a number of hypotheses that can be tested independently from the theory itself.

Any scientific theory must be based on a careful and rational examination of the facts. Facts and theories are two different things. In the scientific method, there is a clear distinction between facts, which can be observed and/or measured, and theories, which are scientists' explanations and interpretations of the facts. 

Some think that theories become laws, but theories and laws have separate and distinct roles in the scientific method. A law is a description of an observed phenomenon in the natural world that holds true every time it is tested. It doesn't explain why something is true; it just states that it is true. A theory, on the other hand, explains observations that are gathered during the scientific process. So, while law and theory are part of the scientific process, they are two different aspects, according to the National Center for Science Education . 

A good example of the difference between a theory and a law is the case of Gregor Mendel . In his research, Mendel discovered that two separate genetic traits would appear independently of each other in different offspring. "Yet, Mendel knew nothing of DNA or chromosomes . It wasn't until a century later that scientists discovered DNA and chromosomes — the biochemical explanation of Mendel's laws," said Peter Coppinger, an associate professor of biology and biomedical engineering at the Rose-Hulman Institute of Technology. "It was only then that scientists, such as T.H. Morgan working with fruit flies, explained the Law of Independent Assortment using the theory of chromosomal inheritance. Still today, this is the universally accepted explanation [theory] for Mendel's Law."

• When does a theory become a fact? This article from Arizona State University says you're asking the wrong question! 
• Learn the difference between the casual and scientific uses of "theory" and "law" from the cartoony stars of the Amoeba Sisters on Youtube.
• Can a scientific theory be falsified? This article from Scientific American says no. 

Kenneth Angielczyk, "What Do We Mean by "Theory" in Science?" Field Museum, March 10, 2017. https://www.fieldmuseum.org/blog/what-do-we-mean-theory-science

University of California, Berkeley, "Science at multiple levels." https://undsci.berkeley.edu/article/0_0_0/howscienceworks_19  

Philip Kitcher, "Abusing Science: The Case Against Creationism," MIT Press, 1982. 

National Center for Science Education, "Definitions of Fact, Theory, and Law in Scientific Work," March 16, 2016 https://ncse.ngo/definitions-fact-theory-and-law-scientific-work  

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Hypothesis vs. Theory: A Simple Guide to Tell Them Apart

By: Author ESLBUZZ

Posted on Last updated: July 27, 2023

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Hypothesis and theory are no stranger to those who conduct studies and work in science. These two terms are often used interchangeably by non-researchers, but they have distinct meanings in the scientific community. Understanding the difference between a hypothesis and a theory is essential for anyone interested in scientific research or critical thinking.

In this article, we will explore the differences between hypothesis and theory and provide examples to help you understand how they are used in scientific research. We will also discuss the importance of these terms in the scientific method and how they contribute to our understanding of the natural world. Whether you are a student, a researcher, or simply someone interested in science, this article will provide valuable insights into the world of scientific research.

To help illustrate the differences between hypothesis and theory, we will provide a comparison table that summarizes the key differences between these two terms and examples of how scientists use hypotheses and theories to explain natural phenomena and make predictions about future events. By the end of this article, you will have a clear understanding of the differences between hypothesis and theory and how they are used in scientific research.

Hypothesis vs. Theory

Hypothesis vs. Theory: Definitions

Understanding hypothesis.

A hypothesis is an educated guess or assumption that is made before conducting research. It is a tentative explanation for a phenomenon or observation that is based on limited evidence or prior knowledge. In other words, a hypothesis is a statement that proposes a relationship between two or more variables, which can be tested through further investigation.

Characteristics of Hypothesis

Hypotheses have certain characteristics that set them apart from other types of statements. These characteristics include:

• Testable: A hypothesis must be testable through empirical research. This means that it must be possible to collect data that can either support or refute the hypothesis.
• Specific: A hypothesis must be specific in its predictions. It should clearly state what is expected to happen and under what conditions.
• Falsifiable: A hypothesis must be falsifiable, which means that it must be possible to disprove the hypothesis if it is not supported by the evidence.
• Parsimonious: A hypothesis should be simple and straightforward. It should not include unnecessary assumptions or variables.

Examples of Hypothesis

Here are some examples of hypotheses:

• If a plant is exposed to sunlight, then it will grow faster than a plant that is not exposed to sunlight.
• If a person consumes more calories than they burn, then they will gain weight.
• If students are given more time to study for an exam, then they will perform better on the exam.

In summary, a hypothesis is an educated guess or assumption that is made before conducting research. It is testable, specific, falsifiable, and parsimonious. Examples of hypotheses include statements that propose a relationship between two or more variables, which can be tested through further investigation.

Understanding Theory

Definition of Theory

In scientific terms, a theory is a well-substantiated explanation of some aspect of the natural world that is based on empirical evidence. It is a collection of ideas that have been tested and confirmed through observation and experimentation. A theory is a framework that explains how and why things work in a certain way. It is a set of principles that can be used to make predictions about future events.

Characteristics of Theory

A theory has several characteristics that distinguish it from other scientific concepts such as hypotheses or laws. Some of the key characteristics of a theory are:

• A theory is based on empirical evidence and is supported by multiple lines of evidence.
• A theory is constantly evolving and can be modified or refined as new evidence emerges.
• A theory is generally accepted as true by the scientific community and is widely used to make predictions and guide research.
• A theory is not a guess or a hunch, but a well-substantiated explanation that has been rigorously tested.

Examples of Theory

There are many examples of well-established theories in science. Here are a few examples:

In summary, a theory is a well-substantiated explanation of some aspect of the natural world that is based on empirical evidence. It is a framework that explains how and why things work in a certain way and is constantly evolving as new evidence emerges. Theories are widely accepted as true by the scientific community and are used to make predictions and guide research.

Hypothesis vs. Theory: The Distinctions

As a writer, it is important to understand the differences between a hypothesis and a theory. These two scientific terms are often used interchangeably, but they have drastically different meanings in the world of science. In this section, we will explore the process of formulation, level of proof, and usage in the scientific community.

Process of Formulation

A hypothesis is an educated guess or assumption made before any research has been done. It is formed so that it can be tested to see if it might be true. Hypotheses are often based on observations or previous research and can be either proven or disproven through experimentation.

On the other hand, a theory is a well-established principle that is formed to explain the things already shown in data. Theories are based on a large body of evidence and have been extensively tested and proven through experimentation. The formulation of a theory requires a lot of research, experimentation, and analysis.

Level of Proof

The level of proof required for a hypothesis and a theory is vastly different. A hypothesis requires a certain level of proof to be considered valid, but it can still be disproven through experimentation. In contrast, a theory has been extensively tested and proven through experimentation, and therefore requires a much higher level of proof to be disproven.

Usage in Scientific Community

In the scientific community, hypotheses and theories play different roles. Hypotheses are used to generate predictions and testable explanations for phenomena, while theories are used to explain and predict a wide range of phenomena. Hypotheses are usually the starting point for research, while theories are the end result of extensive research and experimentation.

To summarize, a hypothesis is an educated guess or assumption made before any research has been done, while a theory is a well-established principle that is formed to explain the things already shown in data. Hypotheses require a certain level of proof to be considered valid, while theories require a much higher level of proof. In the scientific community, hypotheses are used to generate predictions and testable explanations for phenomena, while theories are used to explain and predict a wide range of phenomena.

Hypothesis vs. Theory: Common Misconceptions

When it comes to scientific research, there are several misconceptions about the differences between hypothesis and theory. In this section, we’ll explore some of the most common misconceptions and clarify the differences between these two scientific terms.

Misconception #1: Hypotheses are less important than theories

One common misconception is that hypotheses are less important than theories. This is not true. A hypothesis is the foundation of scientific research, as it is a proposed explanation for an observation or phenomenon. Without a hypothesis, there can be no scientific investigation.

Misconception #2: Hypotheses are guesses

Another common misconception is that hypotheses are guesses. While a hypothesis is an educated guess, it is not a random or arbitrary guess. A hypothesis is based on prior knowledge, observations, and data. It is a proposed explanation that can be tested through experimentation.

Misconception #3: Theories are proven facts

Many people believe that theories are proven facts. This is not true. A theory is a well-substantiated explanation for a set of observations or phenomena. It is based on a large body of evidence and has been repeatedly tested and confirmed through experimentation. However, theories are not absolute truths and are subject to revision or rejection based on new evidence.

Misconception #4: Hypotheses become theories

Some people believe that hypotheses become theories once they are proven. This is not true. A hypothesis can be supported or rejected by experimental evidence, but it does not become a theory. A theory is a broader explanation that encompasses many hypotheses and has been extensively tested and confirmed.

Misconception #5: Theories are more certain than hypotheses

Another common misconception is that theories are more certain than hypotheses. While theories are based on a large body of evidence and have been extensively tested, they are not absolute truths. Theories are subject to revision or rejection based on new evidence, just like hypotheses.

In summary, hypotheses and theories are both important components of scientific research. Hypotheses are proposed explanations that can be tested through experimentation, while theories are well-substantiated explanations that have been extensively tested and confirmed. While there are many misconceptions about the differences between hypotheses vs. theory, understanding these differences is crucial for conducting scientific research.

In conclusion, while the terms “hypothesis” and “theory” are often used interchangeably, they have distinct differences in the scientific method. A hypothesis is an assumption made before any research has been done, formed so that it can be tested to see if it might be true. On the other hand, a theory is a principle formed to explain the things already shown in data.

One way to differentiate between a hypothesis and a theory is to consider the level of evidence supporting each. A hypothesis is a proposed explanation for a phenomenon, but it is not yet supported by sufficient evidence. In contrast, a theory is a well-established explanation for a phenomenon that has been supported by a large body of evidence.

Another way to differentiate between a hypothesis and a theory is to consider their role in the scientific method. A hypothesis is an initial step in the scientific method, where a researcher formulates a testable prediction about a phenomenon. A theory, on the other hand, is the end result of the scientific method, where a researcher has tested and confirmed a hypothesis over time.

It is important to note that a hypothesis can eventually become a theory if it is repeatedly tested and supported by evidence. However, a theory can never become a hypothesis, as it is already a well-established explanation for a phenomenon.

In summary, understanding the differences between hypothesis and theory is crucial for conducting and interpreting scientific research. By using these terms correctly, researchers can communicate their ideas clearly and accurately, contributing to the advancement of scientific knowledge.

Frequently Asked Questions

How can you distinguish between hypothesis and theory?

A hypothesis is an educated guess or a proposed explanation for an observation or phenomenon. It is a tentative explanation that can be tested through experiments and observations. On the other hand, a theory is a well-established explanation that has been supported by a large body of evidence. The main difference between a hypothesis and a theory is that a hypothesis is a proposed explanation that needs to be tested, while a theory is a well-supported explanation that has been tested and confirmed by multiple lines of evidence.

What is the difference between a theory and a hypothesis in biology?

In biology, a hypothesis is a proposed explanation for a biological phenomenon that can be tested through experiments and observations. For example, a biologist might propose a hypothesis to explain why a particular species of bird has a particular beak shape. A theory in biology, on the other hand, is a well-established explanation that has been supported by a large body of evidence. For example, the theory of evolution is a well-established explanation for the diversity of life on Earth.

What is an example of a theory statement?

A theory statement is a statement that summarizes a well-established explanation for a phenomenon. For example, the theory of relativity is a statement that summarizes Einstein’s well-established explanation for the behavior of objects in space and time.

How are hypotheses and theories similar and different?

Both hypotheses and theories are proposed explanations for phenomena. However, while hypotheses are tentative and need to be tested, theories are well-established and have been supported by a large body of evidence. In addition, hypotheses are often specific to a particular observation or phenomenon, while theories are more general and can explain a wide range of phenomena.

What are some examples of the differences between a hypothesis and a theory?

An example of a hypothesis might be that a particular drug will cure a particular disease. An example of a theory might be the theory of plate tectonics, which explains the movement of the Earth’s crust. The main difference between these two examples is that the first is a tentative explanation that needs to be tested, while the second is a well-established explanation that has been supported by a large body of evidence.

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A theory statement is a statement that summarizes a well-established explanation for a phenomenon. For example, the theory of relativity is a statement that summarizes Einstein's well-established explanation for the behavior of objects in space and time.

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The best way to distinguish between hypotheses and theories is to remember that hypotheses are tentative explanations that need to be tested, while theories are well-established explanations that have been supported by a large body of evidence.

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An example of a hypothesis might be that a particular drug will cure a particular disease. An example of a theory might be the theory of plate tectonics, which explains the movement of the Earth's crust. The main difference between these two examples is that the first is a tentative explanation that needs to be tested, while the second is a well-established explanation that has been supported by a large body of evidence.

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Research Hypothesis In Psychology: Types, & Examples

Saul Mcleod, PhD

Editor-in-Chief for Simply Psychology

BSc (Hons) Psychology, MRes, PhD, University of Manchester

Saul Mcleod, PhD., is a qualified psychology teacher with over 18 years of experience in further and higher education. He has been published in peer-reviewed journals, including the Journal of Clinical Psychology.

Learn about our Editorial Process

Olivia Guy-Evans, MSc

Associate Editor for Simply Psychology

BSc (Hons) Psychology, MSc Psychology of Education

Olivia Guy-Evans is a writer and associate editor for Simply Psychology. She has previously worked in healthcare and educational sectors.

On This Page:

A research hypothesis, in its plural form “hypotheses,” is a specific, testable prediction about the anticipated results of a study, established at its outset. It is a key component of the scientific method .

Hypotheses connect theory to data and guide the research process towards expanding scientific understanding

Some key points about hypotheses:

• A hypothesis expresses an expected pattern or relationship. It connects the variables under investigation.
• It is stated in clear, precise terms before any data collection or analysis occurs. This makes the hypothesis testable.
• A hypothesis must be falsifiable. It should be possible, even if unlikely in practice, to collect data that disconfirms rather than supports the hypothesis.
• Hypotheses guide research. Scientists design studies to explicitly evaluate hypotheses about how nature works.
• For a hypothesis to be valid, it must be testable against empirical evidence. The evidence can then confirm or disprove the testable predictions.
• Hypotheses are informed by background knowledge and observation, but go beyond what is already known to propose an explanation of how or why something occurs.

Predictions typically arise from a thorough knowledge of the research literature, curiosity about real-world problems or implications, and integrating this to advance theory. They build on existing literature while providing new insight.

Types of Research Hypotheses

Alternative hypothesis.

The research hypothesis is often called the alternative or experimental hypothesis in experimental research.

It typically suggests a potential relationship between two key variables: the independent variable, which the researcher manipulates, and the dependent variable, which is measured based on those changes.

The alternative hypothesis states a relationship exists between the two variables being studied (one variable affects the other).

A hypothesis is a testable statement or prediction about the relationship between two or more variables. It is a key component of the scientific method. Some key points about hypotheses:

• Important hypotheses lead to predictions that can be tested empirically. The evidence can then confirm or disprove the testable predictions.

In summary, a hypothesis is a precise, testable statement of what researchers expect to happen in a study and why. Hypotheses connect theory to data and guide the research process towards expanding scientific understanding.

An experimental hypothesis predicts what change(s) will occur in the dependent variable when the independent variable is manipulated.

It states that the results are not due to chance and are significant in supporting the theory being investigated.

The alternative hypothesis can be directional, indicating a specific direction of the effect, or non-directional, suggesting a difference without specifying its nature. It’s what researchers aim to support or demonstrate through their study.

Null Hypothesis

The null hypothesis states no relationship exists between the two variables being studied (one variable does not affect the other). There will be no changes in the dependent variable due to manipulating the independent variable.

It states results are due to chance and are not significant in supporting the idea being investigated.

The null hypothesis, positing no effect or relationship, is a foundational contrast to the research hypothesis in scientific inquiry. It establishes a baseline for statistical testing, promoting objectivity by initiating research from a neutral stance.

Many statistical methods are tailored to test the null hypothesis, determining the likelihood of observed results if no true effect exists.

This dual-hypothesis approach provides clarity, ensuring that research intentions are explicit, and fosters consistency across scientific studies, enhancing the standardization and interpretability of research outcomes.

Nondirectional Hypothesis

A non-directional hypothesis, also known as a two-tailed hypothesis, predicts that there is a difference or relationship between two variables but does not specify the direction of this relationship.

It merely indicates that a change or effect will occur without predicting which group will have higher or lower values.

For example, “There is a difference in performance between Group A and Group B” is a non-directional hypothesis.

Directional Hypothesis

A directional (one-tailed) hypothesis predicts the nature of the effect of the independent variable on the dependent variable. It predicts in which direction the change will take place. (i.e., greater, smaller, less, more)

It specifies whether one variable is greater, lesser, or different from another, rather than just indicating that there’s a difference without specifying its nature.

For example, “Exercise increases weight loss” is a directional hypothesis.

Falsifiability

The Falsification Principle, proposed by Karl Popper , is a way of demarcating science from non-science. It suggests that for a theory or hypothesis to be considered scientific, it must be testable and irrefutable.

Falsifiability emphasizes that scientific claims shouldn’t just be confirmable but should also have the potential to be proven wrong.

It means that there should exist some potential evidence or experiment that could prove the proposition false.

However many confirming instances exist for a theory, it only takes one counter observation to falsify it. For example, the hypothesis that “all swans are white,” can be falsified by observing a black swan.

For Popper, science should attempt to disprove a theory rather than attempt to continually provide evidence to support a research hypothesis.

Can a Hypothesis be Proven?

Hypotheses make probabilistic predictions. They state the expected outcome if a particular relationship exists. However, a study result supporting a hypothesis does not definitively prove it is true.

All studies have limitations. There may be unknown confounding factors or issues that limit the certainty of conclusions. Additional studies may yield different results.

In science, hypotheses can realistically only be supported with some degree of confidence, not proven. The process of science is to incrementally accumulate evidence for and against hypothesized relationships in an ongoing pursuit of better models and explanations that best fit the empirical data. But hypotheses remain open to revision and rejection if that is where the evidence leads.

• Disproving a hypothesis is definitive. Solid disconfirmatory evidence will falsify a hypothesis and require altering or discarding it based on the evidence.
• However, confirming evidence is always open to revision. Other explanations may account for the same results, and additional or contradictory evidence may emerge over time.

We can never 100% prove the alternative hypothesis. Instead, we see if we can disprove, or reject the null hypothesis.

If we reject the null hypothesis, this doesn’t mean that our alternative hypothesis is correct but does support the alternative/experimental hypothesis.

Upon analysis of the results, an alternative hypothesis can be rejected or supported, but it can never be proven to be correct. We must avoid any reference to results proving a theory as this implies 100% certainty, and there is always a chance that evidence may exist which could refute a theory.

How to Write a Hypothesis

• Identify variables . The researcher manipulates the independent variable and the dependent variable is the measured outcome.
• Operationalized the variables being investigated . Operationalization of a hypothesis refers to the process of making the variables physically measurable or testable, e.g. if you are about to study aggression, you might count the number of punches given by participants.
• Decide on a direction for your prediction . If there is evidence in the literature to support a specific effect of the independent variable on the dependent variable, write a directional (one-tailed) hypothesis. If there are limited or ambiguous findings in the literature regarding the effect of the independent variable on the dependent variable, write a non-directional (two-tailed) hypothesis.
• Make it Testable : Ensure your hypothesis can be tested through experimentation or observation. It should be possible to prove it false (principle of falsifiability).
• Clear & concise language . A strong hypothesis is concise (typically one to two sentences long), and formulated using clear and straightforward language, ensuring it’s easily understood and testable.

Consider a hypothesis many teachers might subscribe to: students work better on Monday morning than on Friday afternoon (IV=Day, DV= Standard of work).

Now, if we decide to study this by giving the same group of students a lesson on a Monday morning and a Friday afternoon and then measuring their immediate recall of the material covered in each session, we would end up with the following:

• The alternative hypothesis states that students will recall significantly more information on a Monday morning than on a Friday afternoon.
• The null hypothesis states that there will be no significant difference in the amount recalled on a Monday morning compared to a Friday afternoon. Any difference will be due to chance or confounding factors.

More Examples

• Memory : Participants exposed to classical music during study sessions will recall more items from a list than those who studied in silence.
• Social Psychology : Individuals who frequently engage in social media use will report higher levels of perceived social isolation compared to those who use it infrequently.
• Developmental Psychology : Children who engage in regular imaginative play have better problem-solving skills than those who don’t.
• Clinical Psychology : Cognitive-behavioral therapy will be more effective in reducing symptoms of anxiety over a 6-month period compared to traditional talk therapy.
• Cognitive Psychology : Individuals who multitask between various electronic devices will have shorter attention spans on focused tasks than those who single-task.
• Health Psychology : Patients who practice mindfulness meditation will experience lower levels of chronic pain compared to those who don’t meditate.
• Organizational Psychology : Employees in open-plan offices will report higher levels of stress than those in private offices.
• Behavioral Psychology : Rats rewarded with food after pressing a lever will press it more frequently than rats who receive no reward.

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Understanding Science

How science REALLY works...

• Understanding Science 101
• Misconceptions
• The process of science works at many levels — from that of a single study to that of a broad investigation spanning many decades and encompassing hundreds of individual studies.
• Hypotheses are proposed explanations for a narrow set of phenomena. They are not guesses.
• Theories are powerful explanations for a wide range of phenomena. Accepted theories are not tenuous.
• Some theories are so broad and powerful that they frame whole disciplines of study and encompass many smaller hypotheses and theories.

Misconception:  Hypotheses are just guesses.

Correction:  Hypotheses are reasoned and informed explanations.  Read more about it.

Misconception:  Theories are just hunches.

Correction:  In science, theories are broad explanations. To be accepted, they must be supported by many lines of evidence.  Read more about it.

Misconception:  If evidence supports a hypothesis, it is upgraded to a theory. If the theory then garners even more support, it may be upgraded to a law.

Correction:  Hypotheses cannot become theories and theories cannot become laws. Hypotheses, theories, and laws are all scientific explanations but they differ in breadth, not in level of support. Theories apply to a broader range of phenomena than do hypotheses. The term  law  is sometimes used to refer to an idea about how observable phenomena are related.  Read more about it.

Science at multiple levels

The process of science works at multiple levels — from the small scale (e.g., a comparison of the genes of three closely related North American butterfly species) to the large scale (e.g., a half-century-long series of investigations of the idea that geographic isolation of a population can trigger speciation). The process of science works in much the same way whether embodied by an individual scientist tackling a specific problem, question, or hypothesis over the course of a few months or years, or by a community of scientists coming to agree on broad ideas over the course of decades and hundreds of individual experiments and studies. Similarly, scientific explanations come at different levels:

Hypotheses are proposed explanations for a fairly narrow set of phenomena. These reasoned explanations are not guesses — of the wild or educated variety. When scientists formulate new hypotheses, they are usually based on prior experience, scientific background knowledge, preliminary observations , and logic. For example, scientists observed that alpine butterflies exhibit characteristics intermediate between two species that live at lower elevations. Based on these observations and their understanding of speciation, the scientists hypothesized that this species of alpine butterfly evolved as the result of hybridization between the two other species living at lower elevations.

Theories , on the other hand, are broad explanations for a wide range of phenomena. They are concise (i.e., generally don’t have a long list of exceptions and special rules), coherent, systematic, predictive, and broadly applicable. In fact, theories often integrate and generalize many hypotheses. For example, the theory of natural selection broadly applies to all populations with some form of inheritance, variation, and differential reproductive success — whether that population is composed of alpine butterflies, fruit flies on a tropical island, a new form of life discovered on Mars, or even bits in a computer’s memory. This theory helps us understand a wide range of observations (including the rise of antibiotic-resistant bacteria and the physical match between pollinators and their preferred flowers), makes predictions in new situations (e.g., that treating AIDS patients with a cocktail of medications should slow the evolution of the virus), and has proven itself time and time again in thousands of experiments and observational studies.

"JUST" A THEORY?

Occasionally, scientific ideas (such as biological evolution) are written off with the putdown “it’s just a theory.” This slur is misleading and conflates two separate meanings of the word theory : In common usage, the word theory means just a hunch, but in science, a theory is a powerful explanation for a broad set of observations. To be accepted by the scientific community, a theory (in the scientific sense of the word) must be strongly supported by many different lines of evidence . So biological evolution is a theory: It is a well-supported, widely accepted, and powerful explanation for the diversity of life on Earth. But it is not “just” a theory.

Words with both technical and everyday meanings often cause confusion. Even scientists sometimes use the word theory when they really mean hypothesis or even just a hunch. Many technical fields have similar vocabulary problems — for example, both the terms work in physics and ego in psychology have specific meanings in their technical fields that differ from their common uses. However, context and a little background knowledge are usually sufficient to figure out which meaning is intended.

Over-arching theories

Some theories, which we’ll call over-arching theories , are particularly important and reflect broad understandings of a particular part of the natural world . Evolutionary theory, atomic theory, gravity, quantum theory, and plate tectonics are examples of this sort of over-arching theory. These theories have been broadly supported by multiple lines of evidence and help frame our understanding of the world around us.

Such over-arching theories encompass many subordinate theories and hypotheses, and consequently, changes to those smaller theories and hypotheses reflect a refinement (not an overthrow) of the over-arching theory. For example, when punctuated equilibrium was proposed as a mode of evolutionary change and evidence was found supporting the idea in some situations, it represented an elaborated reinforcement of evolutionary theory, not a refutation of it. Over-arching theories are so important because they help scientists choose their methods of study and mode of reasoning, connect important phenomena in new ways, and open new areas of study. For example, evolutionary theory highlighted an entirely new set of questions for exploration: How did this characteristic evolve? How are these species related to one another? How has life changed over time?

A MODEL EXPLANATION

Hypotheses and theories can be complex. For example, a particular hypothesis about meteorological interactions or nuclear reactions might be so complex that it is best described in the form of a computer program or a long mathematical equation. In such cases, the hypothesis or theory may be called a model .

Take a sidetrip

To see an example of how models of the atmosphere can shape policy, explore  Ozone depletion: Uncovering the hidden hazard of hairspray .

• Teaching resources
• You can help students understand the differences between observation and inference (e.g., between observations and the hypothesis supported by them) by regularly asking students to analyze lecture material, text, or video. Students should try to figure out which aspects of the content were directly observed and which aspects were generated by scientists trying to figure out what their observations meant.
• Forming hypotheses — scientific explanations — can be difficult for students. It is often easier for students to generate an expectation (what they think will happen or what they expect to observe) based on prior experience than to formulate a potential explanation for that phenomena. You can help students go beyond expectations to generate real, explanatory hypotheses by providing sentence stems for them to fill in: “I expect to observe A because B.” Once students have filled in this sentence you can explain that B is a hypothesis and A is the expectation generated by that hypothesis.

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Even theories change

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Difference Between Theory and Hypothesis

Many of them belittle evolution because “it is just a theory.” Gravity, on the other hand, must be real because it is a law. The words “theory,” “facts,” “laws” and “hypothesis” have a very specific meaning in the scientific world that doesn’t quite match the ones we use in everyday language. A hypothesis is a tentative explanation of an observation that can be tested. It acts as a starting point for further explanation. Theory, on the other hand, is an explanation of some aspect of the natural world that’s well-justified by facts, tested hypotheses, and laws. Let us look at more differences between hypothesis and theory given in a tabular column below.

Theory vs Hypothesis

From the above differences, we can infer that a hypothesis might change significantly as the testing occurs. A hypothesis can either be right or wrong. When a hypothesis is tested and proved true, it becomes a theory. At BYJU’S, learn more differences like the difference between asteroid and comet.

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Hypothesis VS A Scientific Theory: A Comparison

Categories Philosophy

A hypothesis is an explanation that is proposed for a phenomenon. If a hypothesis has to be scientific, the scientific way needs that it can be tested. Scientists basically base their hypotheses on prior observations that the available scientific theories can’t explain .

A scientific theory on the other hand, is an explanation of an aspect of the natural world or the universe which is tested and corroborated according to scientific ways. In situations where theories aren’t amenable to experimental testing, those theories will be evaluated through the principles of abductive reasoning.

One must keep in mind that even though ‘hypothesis’ and ‘theory’ are usually used interchangeably, both aren’t the same.

The difference between a hypothesis and a scientific theory is that a hypothesis is an assumption that is made prior to any research which has to be done. The hypothesis is tested in order to see if it is true or not. A theory is a principle that has to be formed in order to explain the things that are shown in data.

Here is a table for the differences between hypothesis and scientific theory:

Keep reading to know more.

Page Contents

What is a scientific theory?

A scientific theory explains an aspect of the natural world or the universe, the explanation is tested and corroborated according to the methods of science. In everyday speech, theory refers to an explanation that is a representation of an unsubstantiated and speculative guess. However, in science, the theory describes an explanation that is tested and is accepted as valid.

A scientific theory is different from a scientific fact and scientific law. A fact is merely a basic observation, while a law is a statement. Stephen Jay Gould  wrote that “Facts are the world’s data, while theories are structures of ideas which explain and interpret the facts.”

Learn the differences between fact, theory, hypothesis, and laws through this video.

A scientific theory can be rejected if it’s unfit for the new findings. Many well-established theories are unlikely to be ever changed, such as evolution and cell theory.

Scientific theories are very much testable and can form falsifiable predictions. Theories explain the cause of a certain natural phenomenon, they are also used to describe as well as predict particular aspects of the universe. Like other types of scientific knowledge, a scientific theory is deductive as well as inductive, which aims for predictive and explanatory power. Moreover, Scientists often utilize theories for further scientific information, and also to provide advancements to technology or medicine.

Furthermore, two types of scientific theories were described by Albert Einstein: “ Constructive theories” and “ Principle theories”. Constructive theories are the constructive representation of phenomena, such as kinetic theory. Principle theories, on the other hand, are empirical generalizations, for example, Newton’s laws of motion.

What is an example of a theory in science?

The world is full of theories, and some unbelievable theories are true as a theory is formed to explain the things that exist.

Here are some popular examples of theories in science:

• Big Bang Theory
• Theory of Evolution
• Quantum Field Theory
• Hubble’s Law of Cosmic Expansion
• Universal Law of Gravitation
• Newton’s Laws of Motion
• Laws of Thermodynamics
• Archimedes’ Buoyancy Principle

What does a hypothesis mean?

A hypothesis is often tentative, an assumption or suggestion that is formed strictly for the sole objective of being tested. A hypothesis is an explanation for a phenomenon. A hypothesis is based on prior observations that couldn’t be explained with the scientific theories already available.

The meaning of the adjective “hypothetical” is “Possessing the nature of a hypothesis” or “Assuming to exist as an immediate result of a hypothesis”.

People often refer to a hypothesis as an “educated guess” as it provides an outcome that is based on the evidence. Although, there are several scientists who reject the term “educated guess”. Moreover, experimenters have the right to test and reject the hypothesis prior to solving the problem.

Researchers, while weighing up alternative hypotheses, will take into consideration:

• Testability.
• Scope: The evident application of the hypothesis to several cases of phenomena.
• Fruitfulness: the likelihood of a hypothesis to explain phenomena.
• Conservatism: It’s the degree of “fit” with the existing known knowledge systems.

How do I write a hypothesis?

There are 6 steps that one has to follow to write a plausible hypothesis. Here is all the information that you would need.

• Ask a question

Curiosity has been the inspiration for many of history’s greatest scientific achievements, so the best place to begin is to ask yourself questions about the world as well as the universe. Why are things the way they are? You must choose a research topic that is interesting to you, and your curiosity will come naturally. 

• Conduct preliminary research

Gather all the background information on your research topic. How much background information you require depends on what you are attempting and what topic you chose. You might need to read several books, or it could be as simple as doing a web search to get quick answers. At this stage, you don’t necessarily need to prove or disprove your hypothesis, you merely need to gather the information that you require in order to prove or disprove it yourself. You must know first if you are right in proving or disproving this hypothesis.

• Define your variables

Once you have decided what your hypothesis will be, you will have to select variables that are independent and which are dependent. Always keep in mind that independent variables are the factors that you have absolute control over. Therefore, consider the limits of your experiment before you finalize your hypothesis. 

• Phrase it as an if-then statement

While you write your hypothesis, phrase it by using an if-then format, for example, “ If  I water a plant every day,  then  it will grow better.” This format may be tricky while dealing with multiple variables, however, generally, it’s a reliable way of expressing the cause-and-effect relationship that you’re testing. 

• Collect data to support your hypothesis

A hypothesis is a means to an end. The prime concern of any scientific research is the conclusion. Once you are done with all 4 steps, you can start with your experiments. You will be gathering data to support your hypothesis. However, if your research turns out to prove it wrong, then don’t worry, as all this is a part of the scientific method. 

• Write with confidence

Lastly, you would want a record of your findings in a research paper for other people to read. Write the research paper and be proud that you made it to the last step.

To Conclude

• The hypothesis is a tentative explanation needing scientific testing.
• Scientific Theory is backed by evidence. It is an extensively tested explanation.
• The hypothesis is untested. On the other hand, the Theory is based on existing data.
• Hypotheses need more testing. And theories encompass broad data.
• Scientific theories change, e.g., the Big Bang and the Theory of Evolution.
• The hypothesis can be defined as an “educated guess” to be tested.
• Constructing a hypothesis involves questioning, researching, defining variables, and gathering data.
• Hypotheses explain your predictions. And the theories explain natural aspects.

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Theory vs Law vs Hypothesis

6th - 8th grade, other sciences.

8 questions

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• 1. Multiple Choice Edit 1 minute 1 pt A possible explanation to a problem that has not yet been tested.  data theory hypothesis fact
• 2. Multiple Choice Edit 30 seconds 1 pt A broad and comprehensive statement of what is thought to be true; it is supported by much evidence. hypothesis theory guess fact
• 3. Multiple Choice Edit 1 minute 1 pt Kalinda was trying to explain to her friend the difference between a theory and a law in science.  She used the theory of plate tectonics and the law of superposition as examples.  Kalinda explained the difference by using nonscientific language.  Which statement did Kalinda use to correctly describe the difference between a theory and a law in science? A theory describes a natural event, while a law explains it. A theory explains a natural event, while a law predicts it. A theory explains a natural event, while a law describes it. A theory predicts a natural event, while a law explains it.
• 4. Multiple Choice Edit 30 seconds 1 pt An explanation a scientist makes that we can test to see if it is true or not is a _________. hypothesis theory law question
• 5. Multiple Choice Edit 1 minute 1 pt Martha is curious as to what happened to the dinosaurs.  She is convinced that a virus spread across the earth and killed all the dinosaurs.  Martha’s idea is called a ________. hypothesis theory law question
• 6. Multiple Choice Edit 1 minute 1 pt The law of universal gravitation states that both mass and distance of objects affect the gravitational force between them.  Gravitational force increases as the mass of the objects increase.  Gravitational force decreases as distance between the objects increases.  Why are these statements considered scientific law, and not scientific theory? The statements tells what happens, and not why the even occurs. This statement involves mass and distance measurements. This statement explains the attractive force between two objects. This statement predicts what will happen under certain conditions.
• 7. Multiple Choice Edit 1 minute 1 pt Which of the following can be used to test a hypothesis? experiment theory law variable
• 8. Multiple Choice Edit 1 minute 1 pt In 1897, Joseph Thomson discovered that atoms contained electrons.  He proposed a change in the atomic theory of that time, and the theory was modified because of his discovery.  Since Thomson’s discovery, atomic theory has been further modified.  What is the best explanation for why scientific theories are modified? Theories more than ten years old are usually out of date. Scientists want to prove that the work of other scientists is wrong. New evidence that supports a revision prompts scientists to modify earlier theories. So much information is available today that it is harder to focus research and disprove theories.

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