Paen to Common Sense

It is a verity amongst creationists that science is a faith system, equally problematic, and yet more dogmatic, than religion itself. Sometimes this claim is justified (should we dignify it with such a word) by pointing out that science rests on no ultimate, indestructible bedrock; that scientific propositions defer for their proof on anterior propositions which are not themselves proven, such that science is like the old myth of the earth resting on the back of turtles that go 'all the way down'. I think it is fair to say that this thoroughgoing antifoundationalism, whatever its merits as a philosophical argument, does not imperil the authority of science as a systematic body of knowledge. The fault stems from a confusion over the word 'proof'. It is often said that evolutionary theory is mere theory, since it cannot be proven. If by this we mean that its conclusions follow by the force of logic, such as 2+2= 4 does, then in this sense it is a conjecture. But then, almost everything in science is conjecture - the fact being that evolutionary theory dovetails with the evidence such to make it highly probable. (The biologist JBS Haldane, when asked what evidence could disprove evolution, growled 'rabbit fossils in the Pre-cambrian'.) The point is this: that just because we cannot establish fine-grained, unimpeachable certitudes does not mean we are licensed to say anything whatsoever, in an intellectual free for all. All theories minister to the evidence with greater or lesser degrees of economy, more satisfactory or more comprehensive degrees of plausibility; and so on. According to JS Mill, even mathematics deals in generalisations from the particular; is, in other words, of an inductive character. At the very least they are conditionals: ie, they are of the form, if a, then b follows. And a itself is something which is not provable on its own terms (look up Godel's Incompleteness Theorem'). But what this indicates is not that all viewpoints are faith positions, but that common sense must, of necessity, play a part in our reasoning. (Huxley said that science is 'common sense writ large'; Wittgenstein charged his students 'not treat your common sense like you treat your umbrella'; ie, don't leave it outside).

Common sense, of course, is not something that is open to revision: the view, for example, that the universe obeys universal laws. Or that the world exists as it reveals itself to us, and is not a prisoner of Descartes' demon. John Searle puts it thus: I do not believe that the world exists in the same way I believe that Shakespeare was a great poet. The first is a default position, something which is not amenable to doubt, and which is assumed by any other proposition whatsoever. The latter is an empirical judgement, which stands before the tribunal of experience. We need both, if our words are to mean anything at all.