Alvin Plantinga (via email) kindly accepted my request for a response to my previous treatment of his Evolutionary Argument Against Naturalism (EAAN). What I didn't mention in my earlier post is that this is a revised form of EAAN. So I'll refer to the new argument as "REAAN," so as to distinguish it from the original EAAN.
As far as I can tell, Plantinga stuck to EAAN for the past almost two decades, since he first presented it in Warrant and Proper Function (1993), and notably using it in his 2009 debate with Daniel C. Dennett. I do not know when he first presented REAAN. It might be quite new. [Update: Plantinga has informed me that he does not consider REAAN a revised version of EAAN, and that he embraces the premises and conclusions of both EAAN and REAAN. The latter, he says, is a different but similar argument first proposed by Ric Otte some years ago, though well after EAAN was first proposed. I'll continue to distinguish them as EAAN and REAAN. REAAN does seem like a revised form of EAAN; however, if you prefer not to think of it that way, you can take REAAN to stand for "Ric Otte's EAAN." I don't know why Plantinga presented REAAN as a way of clarifying EAAN. In any case, that accounts for my confusion.]
The main difference between EAAN and REAAN is that the latter appeals to the notion of metaphysical beliefs. Whereas EAAN supposes that the conjunction of naturalism (N) and current evolutionary theory (E) entails an undefeated defeater for all beliefs, the REAAN claims that the same conjunction provides a defeater for metaphysical beliefs. Unlike EAAN, REAAN assumes that (N&E) is a metaphysical belief. Thus, it is argued that the conjunction of N and E produces an undefeated defeater for itself.
Plantinga presents REAAN as follows:
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.
My criticism is as follows: In order for P1 to be true, metaphysical beliefs must be fundamentally detached from practical knowledge. Naturalists (such as Dennett, to take a relevant example), however, are inclined to take their naturalistic point of view as a practical one. Therefore, under this definition of "metaphysical," it is not true that naturalism conjoined with current evolutionary theory (which is a scientific theory, and therefore of a fundamentally practical nature) is a metaphysical belief. Therefore, if P1 is true, P4 must be false. If Plantinga defines "metaphysical" loosely enough so that it includes naturalism, then P1 will be false. So we have the following problem: If P1 is true, then P4 is false.
I didn't quite put it this way to Plantinga over email, but I think I got my basic point across. His response was that the belief in unguided evolution entails a rejection of the belief in a Divine Creator. Essential to theism, he says, is the idea that humanity was created in God's image. This is incompatible with the claim that the creation of mankind occured through a blind evolutionary process. Since (N&E) includes a belief in a blind evolutionary process, it entails a rejection of theism. Therefore, (N&E) is a metaphysical belief.
Let's leave aside for the moment that some theistic views might not involve the idea that humanity was created in God's imagine. I think that idea is peculiar to monotheism, and not theism in general. But we can put Plantinga's argument another way: Essential to some brands of theism is the view that humanity was created in God's image. That view is therefore a metaphysical view. If some other view entails a rejection of a metaphysical view, then that other view is also a metaphysical view. Since (N&E) entails the rejection of a God who created mankind in His image, then (N&E) is a metaphysical belief.
In my view, if Plantinga's counter-argument is sound, and (N&E) really is a metaphysical belief, then P1 would have to be false. If practical beliefs about how mankind came into existence are considered metaphysical beliefs, then the "metaphysical beliefs" mentioned in P1 include at least some practical beliefs. This makes P1 just as implausible as the EAAN premise. Plantinga would do just as well by not mentioning "metaphysical beliefs" at all and sticking to EAAN. But this is going under the assumption that (N&E) is a practical belief, and not of the "metaphysical" sort required to make P1 plausible. In contrast, it might be supposed that (N&E) is not practical at all, and that it is metaphysical in the appropriate sense. It would thus have to be argued that belief in a blind evolutionary process had no pragmatic basis. Unfortunately for Plantinga, such an argument is not likely to be persuasive.
On the one hand, there are pragmatic reasons for distinguishing between processes which are the result of intelligent guidance and those which are not. The science of evolutionary theory does not require any appeals to intelligent guidance. Therefore, there is no pragmatic reason to appeal to it.
Plantinga might argue that there is a difference between not appealing to an intelligent creator in your scientific theory and believing that no intelligent creator is responsible for evolutionary theory. In other words, Plantinga might claim that the scientific view says nothing at all about whether or not the process was ultimately in the hands of a supernatural being, and that naturalists are stepping out of bounds when they reject the claim that God is responsible for the process. This rejection of God, Plantinga might say, is where the mere scientist becomes a naturalist--it is a step from the metaphysical innocence of science to the metaphysical sin of naturalism.
My objection is that naturalists of the best sort commit no such sin. Taking "metaphysical" in the sense required to make P1 true, naturalism as it should be is a skeptical attitude and not a positive metaphysical position. Naturalists will gladly admit that our cognitive faculties are not reliable when it comes to so-called "metaphysical beliefs." Naturalists do not thereby put forward a metaphysical view of their own. Not all views about metaphysical beliefs are themselves metaphysical beliefs. Naturalists see metaphysical belief in practical terms, as a matter of human behavior and practical interest. Thus, when Dennett, for example, says he does not believe in a Creator, he is not putting forward a positive claim about the nature of reality; he is putting forward a skeptical claim about theistic discourse. I queried Dennett about this via email and he affirmed this interpretation of his views.
In conclusion, I see no reason to count naturalists among Plantinga's metaphysicians. The fact that they (or, I should say, we) reject theistic discourse is not reason enough.