When science denialists say "just a theory", they are roundly chastised. Science educators (teachers, reporters, essayists, etc) are united that the word theory has a strong requirement:
- Berkeley: "a theory (in the scientific sense of the word) must be strongly supported by many different lines of evidence."
- Smithsonian: "A theory is a well-substantiated explanation of an aspect of the natural world that can incorporate laws, hypotheses and facts."
- Wikipedia: "It is well-supported by many independent strands of evidence, rather than a single foundation."
However, physicists hold to a completely different view:
- Dr Lubos Motl says a theory is a detailed & cohesive explanation, even if it only applies to "gedanken worlds" (thought experiments that don't match the real universe).
- Physics.SE: in order for something to be called a "law," there must (or at least should) be experimental evidence supporting it. There is no such requirement to be called a "theory."
- Physics.SE: An open-ended program you can publish new fundamental papers about is always called a "theory".
The point is: in science, sometimes theory means a well-supported explanation, and sometimes it really does mean "just a guess". That guess may be deep and mathematically rigorous, accurately replicating a lot of known properties of the universe, but there's no experimental or observational evidence (i.e. verified predictions indicating the hypothesis should supersede the status quo). If respected scientists don't believe that theory means well-supported, then why should anyone else? Why should laypeople accept that their definition is wrong, when scientists get to say that the word means what they want it to mean (neither more nor less)?
Is this discrepancy strictly confined to Physics, or do other branches of science also use theory this way?
We probably can't force physicists to change their usage, so should we chastise the educators and tell them to discuss these exceptions? Currently, they are lying to the public.
Edit #2: This question is about inconsistent use of terminology. If one group of scientists say that planet means "gravitationally-rounded body that has cleared its solar orbit" while another group says it means "wandering light in the sky", then that disagreement would impede the flow of knowledge. Hence, astronomers spent a great deal of effort to choose a single definition for use in scientific discussion. (Whether they chose the right definition or not is a separate issue.)
Accurate communication between scientists requires agreement about the definitions they share (laypeople may continue using whatever definitions they want). There is an unaddressed disagreement among scientists about the meaning of the word theory, which I have documented with references. Hence, I'm seeking to explore viewpoints about word usage among scientists.