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What is a Theory?

Mary McMahon
By
Updated: May 21, 2024

The word “theory” means a number of different things, depending on the context. In the maths and sciences, for example, it is a tested and testable concept that is used to explain an occurrence. For students of the arts, the term refers to the non-practical aspect of their work, while laypeople refer to unproven ideas and speculation as theories. The multitude of meanings for this word can get confusing, but the intent is usually clear from the context; a mathematical paper talking about a theory, for example, is probably referring to it in the scientific sense.

In English, the word dates back to 1592, when it was used to mean a concept or scheme. By the 1630s, scientists had co-opted the term, using it to describe an explanation or thought that was based on observation and testing. “To theorize” also emerged at around the same time.

In the sciences, theories are created after observation and testing. They are designed to rationally and clearly explain a phenomenon. For example, Isaac Newton came up with a theory about gravity in the 17th century, and it proved to be both testable and correct. Scientific theories are not quite the same thing as facts, but they are often very similar; scientists usually test their theories extensively before airing them, looking for obvious problems which could cause them to be challenged.

In mathematics, theories are bodies of knowledge about specific types of mathematics. Mathematicians use things like set theory in the course of their work. Theoretical mathematics can get quite complex and abstract, making it sometimes difficult for laypeople to understand, but it helps to explain everything from the movement of crowds to the origins of the universe.

In the arts, many artists refer to their non-practical work as theoretical. For example, a musician who plays the tuba would use the term to refer to the study of music history, the math of music, and other related material. Art criticism is also a field of theory, since critics discuss artwork, rather than actively producing it, and through their discussions, they contribute to the overall field.

For laypeople, a theory is simply an idea. Some people use the word like they would “hypothesis,” positing an idea that needs to be tested. At other times, an idea may be dismissed as “just a theory,” with the implication that it cannot be proven and it is only a rough idea, not a firm fact or opinion.

All The Science is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.
Mary McMahon
By Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a All The Science researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

Discussion Comments
By anon356740 — On Nov 28, 2013

A theory is a plan or scheme existing in the mind only, but based on principles verifiable by experiment or observation.

By anon350815 — On Oct 08, 2013

A theory involves many thing. A theory is a group of ideas that explains, describes or supports a hypothesis until it is accepted by gurus. One can also describe a theory as a point of view that has been supported with a series of explanations to prove others' ideas. Theory and perspectives are two sides of the same coin, as I view them.

By anon348345 — On Sep 16, 2013

What is a measurement in math?

By anon287782 — On Aug 27, 2012

A theory is the result of a hypothesis being supported by research over and over again until it becomes accepted. Therefore, theory is strong in science.

I hate that the word theory also means "beliefs" for the general people, thus creating confusion.

By anon275101 — On Jun 15, 2012

What is the relevance of this in my course, which is journalism?

By anon253410 — On Mar 09, 2012

@anon239872: Theory, in layman's usage, is equivalent to a hypothesis, while a theory used in science is something that has been proven through observation of evidence, and rigorous testing by various scientists. Basically a scientific theory, like evolution, has graduated with a master's degree from an hypothesis.

By anon253407 — On Mar 09, 2012

@anon118590: Just because we weren't there does not mean we cannot test a claim, and we test a claim through evidence. The fossil records and DNA analysis gave evidence for common ancestry. Furthermore, we observed and tested evolution through dogs, which started out as wolves thousands of years ago and were domesticated by humans. In Russia, there was an experiment that showed wolves looking like domesticated dogs after four or so generations in captivity. We also observe this fact through microorganisms, which evolve to become more resistant to drugs.

By anon239872 — On Jan 11, 2012

Does theory mean hypothesis?

By anon188001 — On Jun 19, 2011

Hmm. I have a theory, that this theory is a theory. Personally, I didn't really know that this word, "theory" had so many different meanings.

Like, I love to do crafty things like Scrapbooking and molding and things like that. But I never knew that the word theory is also use in art. Hmm, Learn something new every day.

By anon176954 — On May 17, 2011

anon161747 - Re Child Labour. Have a look at Grounded Theory.

By EliseP — On May 11, 2011

Lets break down what theory means. Theory basically means to have an idea. Example: She believes there could be other living beings in space.

By anon161747 — On Mar 21, 2011

i am doing a masters thesis and my topic is child labor as seen by children. it's quantitative research but i really don't know which theory i have to apply on this study? anyone have idea about that? Thanks.

By smachuki — On Mar 03, 2011

what is the relevance of theory in sociology?

By gurudevann — On Nov 25, 2010

What is the essence of the theory of sivashanmugam?

By anon118590 — On Oct 14, 2010

Please tell us how evolution was "observed and tested". We didn't observe it and definitely, we can't test it. what is the proof of the test and who tested it?

By anon81168 — On Apr 30, 2010

A metatheory is a theory whose subject matter is some other theory. In other words it is a theory about a theory.

By anon79736 — On Apr 24, 2010

this is a great website! i hope there would be add-ons for literature too!

By anon33241 — On Jun 03, 2009

What is the measurement in math?

Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a...

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