Thoughts in a Haystack

For those interested in Alvin Plantinga's evolutionary argument against naturalism, the Wikipedia article I referenced before mentioned that Branden Fitelson and Elliott Sober had criticized Plantinga's Bayesian argument. I've found the article online at Professor Sober's website.

The arguments are fairly technical but they come to the same conclusion that I did:

Plantinga suggests that evolutionary naturalism is self-defeating, but that traditional theism is not. However, what is true is that neither position has an answer to hyperbolic doubt. Evolutionists have no way to justify the theory they believe other than by critically assessing the evidence that has been amassed and employing rules of inference that seem on reflection to be sound. If someone challenges all the observations and rules of inference that are used in science and in everyday life, demanding that they be justified from the ground up, the challenge cannot be met. A similar problem arises for theists who think that their confidence in the reliability of their own reasoning powers is shored up by the fact that the human mind was designed by a God who is no deceiver. The theist, like the evolutionary naturalist, is unable to construct a non-questionbegging argument that refutes global skepticism.

Consider what Plantinga and other theists have to believe in order to be in any better position than naturalists. First of all, as Fitelson and Sober point out, Plantinga maintains that naturalism and "traditional theism" are the only two "significant alternatives," i.e. that there are no other possibilities worth considering. That has certain consequences: the probability of our cognitive faculties being reliable is high if and only if God exists (or else theists are equally subject to the evolutionary scenario that Plantinga spins). But why should they believe God exists unless whatever arguments in favor of his/her/its existence (even assuming the arguments themselves are good) are the result of reliable cognitive faculties? In other words, the probability of God existing is high if and only if human cognitive faculties are reliable. And the probability of human cognitive faculties are reliable is high if and only if God exists.

It seems to me that such tight circularity is every bit as much a "defeater" of the rationality of theism as the alleged poverty of evolutionarily derived cognitive faculties could possibly be to naturalism.
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