The rest of this post is written by Dr. Plantinga.
Wilkins and the EAAN
John Wilkins represents my evolutionary argument against naturalism (EAAN) as follows:
P1. If evolution is true, then we have modified monkey brains.
P2. Modified monkey brains are not evolved to find out the truth.
P3. Evolutionary naturalism (the view that everything about humans, including their cognitive capacities, evolved) is the output of modified monkey brains.
C1. Therefore evolutionary theory is unreliable and should be rejected.
C2. Therefore evolutionary naturalism should be rejected.
P1 – P3, I take it, are supposed to be premises of my argument, and C.1 and C.2 its conclusions. Wilkins then objects to this argument. I agree with him: this argument is objectionable. I am happy to say, however, that it is not even remotely recognizable as my argument.
I have no objection to P1 to P3 (taking ‘naturalism’ the way Wilkins take it); neither, however is a premise of my argument. While I have no objection to P1 and P3, I do reject P2 (and of course it is not a premise of my argument). I’m inclined to think that in fact our brains have evolved from something like monkey brains, but it certainly doesn’t follow that they haven’t been evolved to find out the truth. Like other Christians, I believe that God has created us, and created us in his image. That means that he has created us in such a way that we too can have at least some knowledge: of the world around us, of ourselves; and also of God himself. So if, as seems likely, we have come to be by virtue of an evolutionary process then God has created us by way of such a process—an evolutionary process has been guided and orchestrated by God. But then P2 is false.
Thus the first main problem with Wilkins’ reconstruction of my argument is that none of the premises he ascribes to me is in fact a premise of my argument. And the second main problem is that in attempting to state my argument, he uses the term ‘naturalism’ in a way completely different from the way I use it. In my argument I take naturalism to be the claim that there is no such person as God or anything like God—no angels, demons, or anything else supernatural. Naturalism is therefore stronger than atheism; you can’t be a naturalist without being an atheist, but you can be an atheist without rising to the full heights (or descending to the murky depths) of naturalism. Wilkins, however, takes naturalism to be something entirely different: “the view that everything about humans, including their cognitive capacities, evolved”. I reject and argue against naturalism taken my way; it is naturalism taken my way that I argue against. On the other hand, I have no objection to naturalism taken Wilkins’ way: since I have no objection to the view that we have come to be by an evolutionary process (one guided or orchestrated by God), I also have no objection to the view that everything about us, including our cognitive capacities, has evolved.
This second problem—his using ‘naturalism’ in a way completely different from its use in EAAN—leads to the third major problem. This problem is that neither of the conclusions he ascribes to my argument is in fact a conclusion of the argument. According to Wilkins’ C1, “evolutionary theory is unreliable and should be rejected”; according to his C2 “evolutionary naturalism should be rejected”. Neither of these is a conclusion of my argument; furthermore, I don’t believe either one. It is not a conclusion of my argument that evolutionary theory is unreliable and should be rejected; as I say, I have no objection to current evolutionary theory. It is also no conclusion of my argument that evolutionary naturalism (naturalism taken Wilkins’ way) should be rejected. Taken his way, ‘evolutionary naturalism’ is just the view that everything about humans, including their cognitive capacities, has evolved; I don’t argue against that thought and have no objection to it.
So I’m sorry to say Wilkins gets my argument really wrong; none of the premises he ascribes to me is in fact a premise of the argument; and neither of the conclusions he ascribes to me is in fact a conclusion of my argument. Furthermore I don’t believe either of the conclusions he ascribes to me.
If Wilkins has the argument wrong, how is it supposed to go? First, the conclusion is that you can’t sensibly accept both current evolutionary theory and naturalism as I defined it; the view that there is no such person as God or anything like God. That’s the conclusion: I am certainly not arguing that evolution is false or can’t sensibly be accepted. What I am arguing is that the conjunction of naturalism with current evolutionary theory is self-referentially inconsistent; it shoots itself in the foot, you can’t rationally believe it. That is because if you believe that conjunction, then you get a defeater for that conjunction—a reason to reject it, to refrain from believing it.
The argument has at least two forms, one with a stronger conclusion and one with a weaker. The stronger conclusion is that a person who accepts (believes) N&E has a defeater for all of his beliefs, of whatever kind. The weaker argument has the conclusion that one who accepts N&E has a defeater for any philosophical or metaphysical beliefs he has—beliefs such as that Plato was right (or wrong) about the forms, or that there is (or isn’t) such a thing as objective right and wrong, or that there is no such person as God, or (Darwin’s example) that “the Universe is not the result of chance”—or naturalism itself. These beliefs are of such a sort that it doesn’t seem to matter, for fitness, for survival and reproduction, whether you hold the belief. (After all, it is only the occasional member of the Young Atheist Society whose reproductive prospects are likely to be enhanced by his accepting naturalism.) Since Wilkins takes Darwin to be offering an argument of this weaker sort, I’ll confine myself to the argument with the weaker conclusion.
The argument goes as follows. First, I’ll use ‘N’ to abbreviate ‘naturalism’, ‘R’ to abbreviate ‘our cognitive faculties are reliable with respect to metaphysical beliefs’ and ‘E’ to abbreviate ‘we and our faculties have come to be by way of the processes appealed to in contemporary evolutionary theory’). Then we can state the argument as follows:
P1 P(R/N&E) is low
i.e., the probability that our cognitive faculties are reliable when it comes to metaphysical beliefs given the conjunction of naturalism with evolution is low.
P2 One who sees that P1 is true and accepts N&E has an undefeated defeater for R.
P3 One who has an undefeated defeater for R has an undefeated defeater for any of her metaphysical beliefs.
P4 N&E is a metaphysical belief.
C One who sees that P1 is true and accepts N&E has an undefeated defeater for N&E and hence can’t rationally accept N&E.
So if she accepts E, she can’t rationally accept N. We can therefore speak of an evolutionary argument against naturalism: if you see that P1 is true, you can’t rationally accept both evolution and naturalism. Evolution is often thought of as a pillar in the temple of naturalism; that’s a whopping error: you can’t sensibly accept both evolution and naturalism.
A couple of comments on the argument. First, P1 is conditional (and a fourth problem with Wilkins’ presentation of my argument is that he seems to have overlooked its conditional character); the claim is on the assumption of naturalism and evolution, the probability of our cognitive faculties being reliable is low. The claim is not that in fact our cognitive faculties aren’t reliable, or that the probability of R just on evolution is low; the claim is that this probability is low given naturalism and evolution.
Second, according to P2, one who accepts N&E and sees that P1 is true has an undefeated defeater for R. For the argument for thinking this defeater is undefeated, see chapter 10 of my Where the Conflict Really Lies.
Third, the conclusion of the argument is that (if you see that P1 is true) you can’t sensibly accept both evolution and naturalism. It doesn’t follow, of course, that you should accept theism, belief in God: you could just be agnostic about theism and naturalism. But it does follow that if you believe in evolution, then for you theism is much more sensible than naturalism.
How strong is this argument? It’s clearly valid; so what about the premises? Perhaps P1 is the premise most needing defense; but surely P1 has a lot to be said for it. According to Wilkins, “what Darwin is arguing is that evolution gives us no confidence in metaphysical conclusions . . . .” Of course the probability of R on evolution alone (without the addition of naturalism) may not be particularly low; the probability of R on E and T (where T is the proposition that God has created us by a process of evolution) will presumably be high. But Darwin was probably assuming something like naturalism as a background condition; his thought, I suggest, is that P(R/N&E) is low. And if that was his thought, he seems to be right. It makes sense to think that natural selection would mold cognitive faculties in the direction of greater reliability when it comes to beliefs relevant to survival and reproduction; but natural selection presumably doesn’t give a rip about beliefs which, like metaphysical beliefs (naturalism, for example), seem not to matter to fitness.
As far as I can see, therefore, the argument is very strong. P1 is true; once you see that, then if you accept N&E you have a defeater for R; if you have a defeater for R, you have a defeater for all your metaphysical beliefs, including N&E itself; but then you can’t sensibly accept both evolution and naturalism. Since there is powerful evidence for evolution, therefore, you should give up naturalism.
 In this connection, note that Wilkins construes my argument as for the conclusion that one can’t sensibly accept supernaturalism: “Plantinga’s EAAN is actually an EAAS (supernaturalism)”. In a way, that’s true: if you accept N&E, then you have a defeater for R and hence for supernaturalistic beliefs such as theism. Of course you’d have to be pretty benighted in the first place if you accepted evolution, naturalism, and also supernaturalism.