PZ Myers dissects Ann Coulter’s ridiculous claim that “There is no physical evidence for evolution” with his usual panache and wit. Of course, he is entirely right: Darwinian evolution is a sacrosant biological fact. Without the theory of evolution, life makes no sense.
But I do think that Myers misinterprets Coulter’s claim. While Coulter says many foolish things, I’m sure she is well aware that thousands upon thousands of science papers have documented the abundance of evidence for evolution. (As Myers notes, PubMed currrently lists 150,000 peer-reviewed articles on evolution.) But Coulter’s claim is more specific: she insists that Darwin’s theory lacks physical evidence. What could this possibly mean?
Coulter’s mistake is an ancient one. She insists that because we can’t touch, taste or dissect evolution, then it can’t really exist. In other words, if something isn’t reducible into physical terms, then it’s just another abstraction, no more tenable than God. This is why Coulter equates “the ideology of evolutionary biologists” with “religious fundamentalism.” For Coulter, both beliefs are acts of faith.
The easiest way to dismantle Coulter’s claim is to refer her to gravity. (I doubt that even Coulter could deny gravity.) It has been four centuries since Newton discovered the force of gravity, and yet we still don’t know what gravity is made of. Like evolution, it can’t be weighed, poked or prodded. The point is not that Newtonian physics doesn’t exist, but rather that we believe in its existence because it helps us explain other things, things that we actually know exist. Gravity explains the orbits of planets, and natural selection elucidates the evolution of life. But if we didn’t have the planets, if we didn’t need to explain the suave motions of stars or the origin of species, then we would have no need to believe in the force of gravity or the logic natural selection.
So while evolution will never be a physical fact in Coulter’s sense, neither will gravity. And yet balls still fall to earth, and the beaks of finches still adjust to last year’s weather. This is one of the ironies of science: our most necessary scientific principles are often the least tangible. As the great philosopher W.V.O. Quine wrote, “The edge of the system [of science] must be kept squared with experience; the rest…has as its objective the simplicity of laws.” The truth of a scientific theory is not determined by how much it weighs, or whether we can see it with the naked eye. Scientific theories must explain stuff, and if they explain stuff – and evolution explains just about everything – then we learn to live with its intangibility. The problem with God is that God explains nothing. This is why religion requires faith, and evolution just requires a glance at the world around you.