Wordweb defines theory as:

A well-substantiated explanation of some aspect of the natural world; an organized system of accepted knowledge that applies in a variety of circumstances to explain a specific set of phenomena

Now, let's consider an explanation:

I fell down because I stumbled unknowingly upon a stone.

According to my very limited knowledge of English, people falling down while walking is an "aspect of the natural world". What stops this explanation from being called a theory? Thank you in advance. :)

  • 1
    If a lot of people were interested in knowing why you fell down, AND the reason wasn't something obvious that everyone could agree on, you could in principle say you have a "theory" to explain it. But in practice your reason is obvious, and no-one would be interested anyway, so you probably wouldn't call that particular "explanation" a theory. We only dignify an explanation with the name "theory" if it's something non-trivial and non-obvious (also, generally speaking the idea / claim should be potentially falsifiable, otherwise it's effectively just belief, faith) Oct 10, 2020 at 16:33
  • @FumbleFingersReinstateMonica Could you please elucidate what you meant by potentially falsifiable? Did you mean that the correctness of an explanation should always be doubted for it to be deemed a theory? If it's correctness is confirmed it will cease to be a theory? Could you please help me by answering my questions? Thank you in advance. :)
    – adieng
    Oct 11, 2020 at 5:00
  • 1
    In the context of scientists (quantum theory, evolution, relativity,...) no-one is interested in an "explanation / theory" unless it's at least possible (in theory! :) to actually test it. So far, no "tests" of those 3 theories have found anything wrong (they haven't been "falsified"), but it's the fact that they could in principle be refuted by experiment that makes them only theories, not "Laws of Nature". Oct 11, 2020 at 11:27

2 Answers 2


The word "theory" has multiple meanings in English.

A "theory" may be an explanation that works in an idealized, imaginary world rather than the world of actual experience. The perfect gas law is an example.

A "theory" may mean an idea that was proposed or is being proposed as an explanation of a general category of phenomena, e.g. Ptolemaic theory.

As used in modern science, a theory is an explanation of a general category of phenomena that covers a broader category of phenomena than any other explanation and is capable of being shown false by observation or experiment. (Different epistemologies vary in the precise definition.) A theory may contain tautologies, but is not in its fullness a tautology. It is rebuttable and broad.

Your example is not a theory in any of those senses.

  • Thank you so much sir for your answer. My example not being a theory in the first sense is understandable. But how is "falling down" which happens to so many people not a general category of phenomena? Sorry if this question is silly but I have only recently graduated from high school with very basic English. Also, by "capable of being shown false by observation or experiment" do you mean that when the correctness of a theory is confirmed it ceases to be a theory?
    – adieng
    Oct 11, 2020 at 5:08
  • There is a theory of "falling down," namely the theory of universal gravitation, which explains a MUCH broader range of phenomena than stumbling on stones. In fact, stumbling on stones does not even explain the entire class of phenomena called "humans falling down." Oct 11, 2020 at 14:47
  • According to modern philosophy of science, no scientific conclusion is ever fully confirmed; it is always subject to modification or rejection by evidence. If a conclusion cannot possibly be falsified by observation or experiment, it is not a scientific conclusion. It is the testability of science that makes it science. . Oct 11, 2020 at 14:52

Nothing stops it being called a theory. There is a lot of nonsense talked about the word "theory"...

It starts with "Darwin's theory of natural selection". People who wanted to ban it from schools claimed "It's only a theory, not science fact. Because it's a theory, we shouldn't teach it." People who wanted to teach it said, "Theory doesn't mean that. Theory means a 'well-substantiated explanation of some aspect of the natural world'. So we should teach Darwin's theory."

They then went on to make a point of "what is a theory" and test students on their ability to remember the definition. But in actual use there are many senses of "theory", from "unproven but testable idea" to "the non-practical aspect of the subject (music theory)"

"Theory" in the definintion in your question is being defined to capture the meaning of "theory" in "Theory of Evolution" and "Theory of Relativity". These are both organised systems of knowledge (there are many aspects to these theories but the parts work together. In relativity the parts are "spacetime", "constant speed of light", "Lorentz transformations" ,"equivalance of gravity to acceleration" E=mc² etc etc.)

You can call your tripping example a "theory". But it's a bit too small to be a "scientific theory" in the way that the theory of relativity is a theory. It's not an organised system of accepted knowledge. It's just too trivial.

  • What is an organised system of accepted knowledge? Could you please explain it to a person (me) who is not very bright? I just know what is "accepted knowledge" but could you please give an example of an organised system of accepted knowledge?
    – adieng
    Oct 10, 2020 at 17:00
  • The theory of relativity is a theory in this sense.
    – James K
    Oct 10, 2020 at 17:50
  • What makes it organised? Thank you in advance.
    – adieng
    Oct 10, 2020 at 17:54
  • The parts of the theory fit together and are designed to fit together. There are not just lots of random facts.
    – James K
    Oct 10, 2020 at 18:13
  • These things are easy for you but not for a lot of us. Thank you so much, sir.
    – adieng
    Oct 11, 2020 at 4:50

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