Evolution and falling apples

I've again heard a respected scientist misrepresent gravity to get some points on creationists. It's kind of a pet peeve of mine, and it's time to vent.

Denying evolution is often compared with denying gravity. That is almost right, so I understand its appeal. There is even a quote from Stephen J. Gould that I use myself that does this, in which he says "I suppose apples might begin to rise tomorrow, but the idea doesn't deserve equal time in the physics classroom". This comparison is made when discussing the meaning of theory in science. A scientific theory is very well established and not at all like the common use of the word theory as a wild guess. We have the atomic theory, the germ theory of disease, and the theory of gravity, and evolution is no less certain than any of them just because we call it a theory.

I agree with that. I say it all of the time. The problem is when the theory of gravity is misrepresented as "things fall". "Things fall" is a simple observation, a fact. No one ever doubted it. Sometimes people say Newton discovered gravity with the implication that until Newton, we weren't sure if apples fall up or down, but he answered it for us. Newton didn't discover that things fall. His discovery was that the same force that makes an apple fall also controls the motion of the planets, and that the force of gravity has a specific mathematical relationship to mass and distance (prior to Newton, falling was attributed to a tendency internal to the apple to seek out a low position, in the teleological reasoning typical of Aristotle).

The latter part is the theory, not that apples fall. Technically, Newton discovered a law, not a theory, although the explanation of orbits could be called a theory. It was criticized in its day as not being a full theory, because we did not know how gravity worked, only mathematical relationships. It wasn't until Einstein and the theory of general relativity that we had a full theory of gravity (and even now it is incomplete at the quantum level).

So I agree that evolution is as strong as the theory of gravity (or better to say general relativity). The problem is when scientists then score cheap points and imply that denying evolution is the same as denying that apples fall. No, denying evolution is the same as saying gravity doesn't control the motion of the planets or that it is not caused by the shape of the space-time continuum. That is still absurd, but not quite the same.

I try to emphasize to students that a theory is a complex structure that incorporates laws and hypothesis and explains a wide variety of observations. If we then say that "apples fall" is a theory, how are we helping them to understand what exactly a theory is? The comparison to gravity is OK as long as we make it clear gravity is a complex explanation for a wide variety of observations, not simply the tendency to fall. Doing that makes for an easy cheap shot, but it is not accurate and we should not use it.