Nearly two decades ago, Alvin Plantinga developed an argument against naturalism (the Evolutionary Argument Against Naturalism, EAAN) that purports to show that naturalism and evolution are incompatible. You can find a version of this argument, as well as Plantinga’s responses to several objections in this paper. 

It has become commonplace for apologists to lean heavily on this argument and to suggest that naturalism cannot account for the reliability of human cognitive powers. William Lane Craig makes such an argument in this op-ed article. It should be noted that Plantinga’s argument, if correct, shows only that naturalism together with evolutionary theory cannot both be true; one or the other can be maintained, but not both together. However, given that evolutionary theory is the most widely accepted naturalistic account of human origins and development, it has become commonplace for the argument to be stated more simply as the claim that naturalism cannot account for the reliability of our cognitive faculties.

As readers of this blog might know, I have no interest in defending metaphysical naturalism. I suspect that it is probably true, but I grant the possibility that it is false and I see no reason to defend it against all comers. Naturalism is best understood as a methodological commitment; we should try to explain as much as we can, as best as we can without having to resort to phenomena that transcend the natural world. In general, commitment to any metaphysical account of ultimate reality is more of a hindrance to the pursuit of knowledge and wisdom than a help. Since the state of our knowledge about reality is characterized by a great deal of ignorance and half-understood theory, I think that it is best to be humble.

So, my interest in Plantinga’s argument has to do not with whether it defeats naturalism, but in its use as an argument for the existence of God. Plantinga thinks, as do many apologists, that theism can account for the reliability of our cognitive faculties. As with many beliefs of a religious nature, I think that this one is the result of a failure of imagination. In the article “Naturalism Defeated” (linked to above), Plantinga says this:

Now according to traditional Christian (and Jewish and Muslim) thought, we human beings have been created in the image of God. This means, among other things, that he created us with the capacity for achieving knowledge—knowledge of our environment by way of perception, of other people by way of something like what Thomas Reid calls sympathy, of the past by memory and testimony, of mathematics and logic by reason, of morality, our own mental life, God himself, and much more. (pp 2-3)

But is it true that we should expect God to create creatures with reliable cognitive faculties? Why would we think so? If God had a good reason to create humans with unreliable faculties, then wouldn’t he do that? Perhaps there is some greater good that God can only realize by creating creatures with deficient cognitive faculties. How can we know that there isn’t? I suppose it is open to the theist to insist that God does not have a reason to create humans with unreliable cognitive faculties, but how would they know? It is certainly possible that God does have such a reason and that, given our epistemic position, we are unable to know what this reason is. I conclude, therefore, that there is no reason to suppose that God does not have such a reason. If he does have such a reason, then, if theism is true, our cognitive faculties are not reliable. Thus, theism does not account for the reliability of our cognitive faculties.

Perhaps you notice an affinity between the above argument and a certain kind of response to the problem of evil known as skeptical theism. Skeptical theism maintains that, given our epistemic situation, there is no reason to believe that we are in a position to know what reasons God might or might not have to engage in certain activities (such as, for example, refraining from saving children from tornadoes or deranged gunmen). Because we cannot know what reasons God might have, we are not in a position to say with confidence that God does not have a reason for permitting any instance of evil, no matter how gratuitous that particular evil might seem to us.

[Here is a very good discussion between three Christian philosophes about the problem of evil. They begin discussing skeptical theism at about the 16 minute mark.]

Regardless of whether a particular theist adopts a robust version of skeptical theism, many, if not most, agree that at some point in a response to the problem of evil, we will have to rely on the fact that we cannot discern all of God’s reasons. But if it is true that God might have reasons beyond our ken for engaging in some activity, then how can we know that God does not have good reasons for creating creatures with unreliable cognitive powers?

It is important to note that even theists who do not espouse skeptical theism are faced with a problem here. How does the theist get around this inference: For all we know God has very good reasons for wanting human cognitive powers to be less than reliable. Thus, if theism is true, for all we know, human cognitive faculties are not reliable.