Thursday, August 27, 2009

God, Darwin, and Conservative Kumbaya

In a recent op/ed in The New York Times, Robert Wright offers a "grand bargain" in a bid to arrange a ceasefire in the war between the religious and those who accept evolution. We can form, he argues, a theory completely consistent with evolution by simply adding a designer. This sort of neo-deism would be a compromise that could suit everyone and we could have cultural peace (and an embarrassing bad loan erased from the ledgers of contemporary conservatism). Put the religious peanut butter in the biological chocolate. Evolution with God tastes great and is less filling. It's conservative Kumbaya.

The whole argument is reminiscent of the White Queen's claim in Through the Looking Glass to believe six impossible things before breakfast. Are beliefs really open to this sort of negotiation? It is certainly true that we can have two theories -- Darwin plus God and plain old Darwin -- which make all the same predictions and are supported by all the same evidence, but yet seem to say different things about what really exists in the universe. But what seems odd is that the question "Which of these theories ought we think is true" is somehow not a concern of philosophy, but simply a matter of politics.

Philosophers are used to cases like this. Indeed, philosophers of physics had a case in the 20th century that was completely analogous. Isaac Newton proposed a gravitation theory in which we have a space that is flat as a board and not influenced by the matter and energy in it. He added a second object, a gravitational field, that caused all massive objects to attract each other. Albert Einstein proposed a different theory in which space was not flat and did warp from the mass and energy it contained in such a way that we understand gravitational effects in terms of the interaction of stuff with a reactive space. Einstein's theory explained and predicted things that Newton didn't -- things like the strange orbit of Mercury and the bending of light rays near large bodies -- so, Einstein is right, space is curved and Newton is wrong that space is flat.

Hold on. It's not so simple. It turns out that we could use Einstein's mathematical trick in reverse and give Newton a curved space and Einstein a flat space and keep the two theories predictions all the same. So, if we could have flat Einstein or curved Einstein in a way that both are supported by all the same evidence, which is it? Is space curved or not?

A group of philosophers called the Logical Empiricists led by Hans Reichenbach, who had been a member of Einstein's very first seminar on general relativity at the University of Berlin and whom Einstein would use his political muscle to bring to the University of Berlin until the Nazi purge of 1933, argued that these two were in fact the same theory. If two theories say the same thing about everything that could possibly be observed, then they are the same theory just expressed in different ways. Geometry is not a real aspect of the universe, but just part of the grammar used in talking about it. the theory may look different in French and German, but it's still the same theory. It is a free choice, a linguistic convention, that does not affect what the theory says about the world.

If we apply this to the case of evolution, it would mean that plain old Darwin and Darwin plus God are the same theory and that the God talk is just a way of speaking, just as an atheist who says "I swear to God I not believe in a deity" is not uttering something self-contradictory. This is clearly not what Wright has in mind since those on the right would now see this as a lousy bargain.

But in the 70s and 80s, there arose strong objections to the Logical Empiricist line. Thinkers like John Earman, Michael Friedman, and Clark Glymour argued that we could have good reason to prefer one of the space-time theories over the other. It may be the case that every observation that is evidence for the flat theory is also evidence for the curved one, but just because the two theories have the same confirming instances doesn't mean that they are confirmed to the same degree by them.

Theories make claims that are observable and have metaphysical commitments, that is, they say things about what exists. Think of evidence as income for a theory and think of metaphysical commitments as debts it owes. The degree of confirmation, the likelihood of a theory's truth, is the cash that's left over when it uses its evidential income to pay off its metaphysical loans. Two competing theories are suitors trying to get our hand in belief and the criterion of theory selection they propose is a gold-digger's version of Occam's razor, prefer theories that are the best confirmed, those that have the most cash in their evidential bank account.

Because flat space requires two entities -- a flat space and a gravitational field -- it has more of a debt load than its curved competitor which posits only the existence of a space. As such, they share all the same evidence, but that evidence makes curved theories better supported by that same evidence because the flat version has extra metaphysical baggage and like the airlines these days, you have to pays for baggage. As such, they contend, there is good reason to believe that space is in fact curved.

In the same way, plain old Darwin has less of a metaphysical debt to pay off than Darwin plus God. So, even though Wright is absolutely correct that the two theories are empirically equivalent, there does seem to be rational, non-political reasons to prefer Darwin without God.

Wright is arguing that we should accept the marriage proposal from the poorer suitor because even he has less evidential money, it would make Thanksgiving dinner more pleasant. He is offering a Marxist version of Pascal's Wager. Pascal argues that if you do a cost/benefit analysis of personal belief in God, that rational self-interest makes it more reasonable to believe. Wright is saying don't think of your self, consider the whole community and give in to the Hegelian synthesis of the theists thesis and the evolutionists antithesis as a higher form of thought that will break the bonds of alienation of one from other and each as a species being.

In the end, the proposal is a lot like a puppy -- cute, silly, but cute. Someone needs to pat Wright on the head, scratch his belly, and give him a toy because his article is simply one big category mistake.