On beliefs, theories, and facts

Like PZ, I too received a copy of What We Believe but Cannot Prove: Today's Leading Thinkers on Science in the Age of Certainty [amaz] a few weeks back. Also like PZ, I was taken with Ian McEwan's entry (see PZ's post for that). I also liked this comment from Seth Lloyd:

Unlike mathematical theorems, scientific results can't be proved. They can only be tested again and again until only a fool would refuse to believe them.

Unfortunately there are a lot of fools out there, many of them supporters of ID. As Chris Anderson, editor-in-chief of Wired notes,

The Intelligent Design movement has opend my eyes. I realize that although I believe that evolution explains why the living world is the way it is, I can't actually prove it. At least not to the satisfaction of the ID folk, who seem to require that every example of extraordinary complexity and clever plumbing in nature be fully traced back (not just traceable back) along an evolutionary tree to prove that it wasn't directed by an Invisible Hand. If the scientific community won't do that, then, the argument goes, they must accept a large red "Theory" stamp on the evolution chapter in the biology text books and the addition of chapters on alternative theories, such as "guided" evolution and creationism.

So, by this standard, virtually everything I believe in must now fall under the shadow of unproveability. This includes the belief that democracy, capitalism, and other market-driven systems (including evolution!) are better than their alternatives. Indeed, I suppose I should now refer to them as the "theory of democracy" and the "theory of capitalism" and accept the teaching of fascism and living Marxism as alternatives in high school.

While I don't necessarily agree regarding capitalism as necessarily being better than their alternatives (and that is a discussion for another day), Anderson's point is well taken.

I should say that I don't accept the idea of "belief" in a scientific theory - one accepts the theory because it explains something otherwise unexplainable. One is reminded of Gould's claim:

Well, evolution is a theory. It is also a fact. And facts and theories are different things, not rungs in a hierarchy of increasing certainty. Facts are the world's data. Theories are structures of ideas that explain and interpret facts. Facts do not go away when scientists debate rival theories to explain them. Einstein's theory of gravitation replaced Newton's, but apples did not suspend themselves in mid-air, pending the outcome. And humans evolved from apelike ancestors whether they did so by Darwin's proposed mechanism or by some other, yet to be discovered.

Moreover, "fact" does not mean "absolute certainty." The final proofs of logic and mathematics flow deductively from stated premises and achieve certainty only because they are not about the empirical world. Evolutionists make no claim for perpetual truth, though creationists often do (and then attack us for a style of argument that they themselves favor). In science, "fact" can only mean "confirmed to such a degree that it would be perverse to withhold provisional assent." I suppose that apples might start to rise tomorrow, but the possibility does not merit equal time in physics classrooms.