One of the reasons that many people have a misunderstanding of evidence in science has to do with the differences in terminology used by scientists and by the general public.  The biggest misunderstanding is around the word theory.

How many times have you, or someone you known, come upon a situation they didn’t fully understand and then propose an explanation.  They’ll typically start that statement with “I have a theory…”.  But they don’t have a theory, they have a guess.  Out of some random facts that happened to be around they guessed at an explanation.  It might be true, it might not, there might be a lot of missing facts they used in the process.  They may have cherry picked facts, either intentionally, or just because of some other built in bias.  It’s just a guess.

The truly diligent folks might come up with with a way to test their guess, that makes it a theory, right?  No, it doesn’t.  If they come up with a set of tests that would either prove or disprove their guess, that makes it a hypothesis.  This is where science begins, an explanation to a phenomenon that has a way to prove or disprove if it is true, and that could predict other behavior in the future.

If you have a hypothesis, and rigorously test it over and over again, creating multiple experiments with control groups, publish a number of scientific papers reviewed by your peers, get feedback from a great deal of other people proposing counter hypothesis, and yet it remains widely believed by experts in the field that your hypothesis best fits all the data at hand… then, and only then, you get to call it a theory.