Friday, August 01, 2008

Plantinga pulls a Samson

Alvin Plantinga throws out a cute little argument against naturalists, or, in other posts here, reductionists, in the July/August 2008 issue of Books & Culture. It is quite a straightforward move, almost syllogistic, and it goes like this:

Naturalists say that science proves their position, and in particular evolution. Plantinga disagrees. “Evolution and naturalism are not merely uneasy bedfellows,” he writes. “One can’t rationally be an evolutionary naturalist.” Now why does he say this?

Here’s the critique: if the mind has arrived by means of evolutionary processes, forces conditioned by history and the larger cosmological context, then how do we know that what it thinks is true is true? Plantinga quotes Darwin:

With me the horrid doubt always arises whether the convictions of a man’s mind, which has been developed from the mind of the lower animals, are of any value or at all trustworthy. Would anyone trust in the convictions of a monkey’s mind, if there are any convictions in such a mind?[1]

He goes on to say that for the naturalist, beliefs, along with other mental states, are caused by neurophysiology. And evolution says that this equipment has been adapted, and is still adaptive for the purpose of genetic reproduction. I like his quote from Francis Crick, “Our highly developed brains . . . were not evolved under the pressure of discovering scientific truth, but only to enable us to be clever enough to survive and leave descendents” (from The Astonishing Hypothesis). Natural selection doesn’t care about truth, it cares about sex, and if false beliefs mean more sex, then that is fine.

Plantinga, with the help of a math buddy, asks, then, what is the chance that any one proposition is true? Out of one hundred beliefs, how many will be false and how many will be true. Answer: not even a handful, and there’s no way to tell one way or the other.

Evolutionary naturalism, then, is self-refuting. Or, as he says, “One who accepts evolutionary naturalism has a defeater for the belief that her cognitive faculties are reliable: a reason for giving up that belief, for rejecting it, for no longer holding it.”

What this means is that evolution spoils naturalism of its epistemological power. The reductionist is the one in danger of falling into an unholy skepticism (although Plantinga points out that Aristotle, the Stoics, and Hegel managed to be atheists without simultaneously embracing naturalism.) And what about the Christian? Well, is there any need to explain it? Get thee, saint, to Augustine and read his de Magistro, and get thee to the imago Dei, the doctrine of the logos, of creation, and of general revelation.

[1] Letter to William Graham (Down, July 3, 1881, in The Life and Letters of Charles Darwin, ed. Francis Darwin (London: John Murray, 1887), Volume 1, pp. 315-16.

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