Published online by Cambridge University Press: 01 January 2020
In his recently published two-volume work in epistemology, Alvin Plantinga rounds out the discussion (in characteristic fashion) with a subtle and ingenious argument for a striking claim: in this case, his conclusion is that belief in evolutionary naturalism is irrational. Now this claim is not of itself so very surprising; the tantalizing feature here lies rather in the nature of the argument itself. Plantinga contends that taking seriously the hypothesis of evolutionary naturalism (hereafter, N & E) ought to undermine one's confidence in the reliability of our basic cognitive faculties. And if one withholds belief in cognitive reliability, it seems that one ought likewise to refrain from believing propositions that are the output of such faculties. And, for evolutionary naturalists, one such output is belief in evolutionary naturalism itself. Hence, quite apart from comparative evidential considerations that might lead one to prefer theism (or one of its competitors) to N & E, but rather owing to a sort of internal inconsistency (in a suitably broad sense), belief in N & E is shown to be epistemically defective. This is a bold and intriguing suggestion indeed. Let us take a closer look.
1 Warrant: The Current Debate and Warrant and Proper Function (Oxford: Oxford University Press 1993). The argument I discuss is given in Ch. 12 (’Is Naturalism Irrational?’) of the second volume. Citations in the text will refer to this chapter.
2 Where this may be construed as either an epistemic or objective probability. As Plantinga suggests (n.7), epistemic probability in this context will follow the conjectured objective probability.
3 Actually, he puts the argument in terms of P(R/N&E&C) for a hypothetical population of creatures much like ourselves, so as ‘to avoid irrelevant distractions’ (222) and then goes on to apply the argument’s conclusion in a straightforward manner to the case of actual human beings. For the moment I will ignore this complication in order to simplify the exposition. I will consider its bearing on Plantinga’s main argument in IV.
4 Actually, there may be reason to hesitate here. As I claim below, it is reasonable to suppose that our own cognitive faculties are basically reliable, even though, arguably, there is no non-circular evidence available to support that claim. It’s not so clear to me that it is improper to make a similar presumption in relation to other creatures we observe who appear to us to be acting upon true beliefs. But it seems Plantinga can sidestep this doubt by adding that we are not to suppose that this hypothetical scenario takes place in a world like our own. Clearly there are ever so many (at least epistemically) possible worlds where agents are radically deceived about themselves and their environments, even if we may reasonably assume that this is not true of our own. If we are not given that the world in question is similar to our own in the relevant respects, then clearly enough no assumption of reliability on our part is warranted.
5 Unless, of course, she is unduly optimistic about how much is already known about the finer details of the course of our evolutionary development. Patricia Churchland, in some of her remarks quoted by Plantinga, is easily interpreted to have such optimism, as well as to hold that P(R/N&E&C) is fairly low, and, accordingly, that P(R), all things considered, should be considered to be low! She seems to be unaware of the fateful next step to which this forces her.
6 An earlier version of this paper was subjected to careful, critical discussion over three sessions of the Philosophy of Religion Discussion Group at the University of Notre Dame in the Fall of 1992. I am grateful to various participants, including AI Plantinga, for the advice and criticisms I received on those occasions, especially for their helping me to see that an argument I originally used in III was irremediably flawed. I also presented the paper at a meeting of the Society of Christian Philosophers at Wheaton College in January, 1994, and I thank my audience on that occasion for their comments. Finally, I wish to express appreciation to Carl Ginet for his helpful suggestions when I first drafted this material.