Wikipedia defines a scientific theory as

an explanation of an aspect of the natural world and universe that has been repeatedly tested and corroborated in accordance with the scientific method

I'm curious about the history of the repeatedly tested and corroborated portion of this definition. This is also reflected in the popular claim that a "hypothesis becomes a theory if tested and proven".

This notion does not appear to come from philosophical circles - I have not found any discussion of e.g. what level of evidence is required for a scientific hypothesis to become a scientific theory. Obviously, there is general consensus that supporting evidence is a requirement for something to be a "good" or "correct" scientific theory; but they also are more than happy to discuss "wrong" scientific theories - which is an oxymoron if a theory is definitionally well-supported.

The "well-supported" criterion dates back to at least the late 90s. In every early source I've found, it's enmeshed with the debate with debates about creationism vs. evolution. In particular - it seems to be be almost exclusively invoked to either combat or preempt claims that evolution is "just a theory".

Based on not finding any earlier references, I suspect that this particular line of discourse (which AFAICT began several decades earlier) is in fact the origin of the criterion that a scientific theory must be well-substantiated by definition.

However, I've found no acknowledgement that this change occurred, or even a historical overview comparing the relative prevalences of said definitions. Are there any such lineages, or discussions of the value of various definitions of "scientific theory" dating to that time? Alternatively are there references to scientific well-supportedness as a necessary criterion for scientific theories pre-dating (or at least existing independently of) the creationism/intelligent design debates?

  • A well-supported scientific theory can still be wrong, it is not an oxymoron. Aether was well-supported in its day. I am not sure how much "acknowledgement" of shifting colloquial meanings we can expect beyond dictionaries/encyclopedias, and by whom. "Definition" applies to them only loosely to begin with. There is no agreed upon "definition" of "scientific method" either, and demarcation of science also remains controversial.
    – Conifold
    Jun 9, 2023 at 5:05
  • @Conifold I understand that any answer will be incomplete and based on certain perspectives - I'm mainly trying to understand who first asserted that "having a lot of evidence" is a prerequisite for anything they would call a theory - and moreover in what context that assertion was first made. Jun 9, 2023 at 5:19
  • You are looking for a history of the philosophy of science. Experiments were critical for Bacon, and large quantities of data important for Hume. The logical positivists tried to overcome Hume's critique of the logic failings of empirical knowledge, but that was not successfully done until Popper -- who mostly used "hypothesis" rather than theory. the revival of theory as a super-validated hypothesis was a tweak to Popper that was probably concurrent. And it is not important -- what matters is the endorsement by the relevant Scientific Professional Society of the truth of the theory.
    – Dcleve
    Jun 9, 2023 at 6:07
  • I think that humans have always accepted explanations that work better than the alternatives.
    – Scott Rowe
    Jun 9, 2023 at 12:34

1 Answer 1


Wiktionary and etymonline have theory and theoretical respectively in their modern usage as conjecture and hypothetical from the 18th century, while the scientific sense as a coherent analysis of the relationship between facts is from the 17th, or, per M-W, the late 16th century. Comfortably before anyone ever thought of natural selection, in any case. Supposing that to relate facts (as opposed to guesses or mistaken beliefs) is to be well-supported, that would push the use you're looking for back about four hundred years.

Theory itself is an Anglicization by way of French of the Greek for contemplation, with multiple divergent meanings that all mean contemplation with some level of nuance.

Both the "it's a mere theory!" and "theories are super, not mere!" lines miss the point, anyway. "It's a mere theory!" picks the wrong homonym. And the response/pre-emption should just be to point out the homonym mistake and clarify the intended meaning.

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