Is Naturalism Self-Defeating?

Alvin Plantinga – John A. O’Brien Professor of Philosophy Emeritus at the University of Notre Dame

Edited Transcript:

The first premise is: if naturalism and evolution were true together, then our faculties would probably not be reliable. Then the second premise is this: if you see that the first premise is true, and furthermore, you believe naturalism and evolution are true, then you have a defeater for your belief that your faculties are reliable. A defeater is a reason to give up that belief, a reason not to accept it any longer.

So a defeater for a belief I have is another belief I come to have, such that as long as I hold that second defeating belief, I can no longer sensibly, rationally hold the first belief, the defeated one.

So what I say then in my second premise is: if you see that the probability of our faculties are reliable is low, given naturalism and evolution … then you have a defeater for the fact that your faculties are in fact reliable. If you have a defeater for that, you have a defeater for any belief that is formed on the basis of your cognitive faculties, which, of course, is all of them.

Then, in particular, you get a defeater for naturalism and evolution, that thing you started off believing … In this way, believing in naturalism and evolution is – you might say – self-defeating. It shoots itself in the foot. It is self-referentially inconsistent, if you want a more philosophical-sounding name for it.

Discussion Questions:

1. Naturalism is the idea that nothing exists beyond the natural world. Many naturalists also believe that human beings came to exist through evolution. Why does Alvin Plantinga argue that naturalism is inconsistent with a belief in evolution?
2. How do you think naturalism relates to scientism?
3. If evolution is a defeater against naturalism, how might evolution relate to non-naturalistic worldviews?