Scientific theories have been getting a bum rap, which hurts everyone. Part of the problem has to do with people confusing the scientific term with the colloquial use of the word "theory."
In today's NYTimes, a marvelous short piece, It's Never 'Just' a Theory', starts out, "Theories are neither hunches nor guesses. They are the crown jewels of science."
The problem is that "in everyday conversation, we tend to use the word “theory” to mean a hunch, an idle speculation, or a crackpot notion, [as in,] "Megyn Kelly...has a theory about why Donald J. Trump hates her" [or] "Mothra P.I. has a theory about how cats can assume a new state of matter."
According to Kenneth R. Miller, a cell biologist at Brown University, in science “a theory is a system of explanations that ties together a whole bunch of facts. It not only explains those facts, but predicts what you ought to find from other observations and experiments.”
Peter Godfrey-Smith, the author of “Theory and Reality: An Introduction to the Philosophy of Science,” offers a useful metaphor for theories: maps. “There are fantastically good maps where there’s not a shred of doubt about their accuracy. And there are maps that are speculative.”
Scientists test out old and new theories against all available evidence. Many theories have been cast aside while others "are the foundation of modern science, such as...the theory that the sun is at the center of the solar system, and the germ theory of disease."