This article is going to seem more technical than most of my posts, especially at first. However, if you persevere to the end, I think you’ll be rewarded. The gist of the argument I describe here is this: many people who believe in naturalism (a form of atheism in which the natural world is all there is) also believe in evolution (the theory that human beings are the result of “lower” life forms changing through an unguided process, by chance and natural selection, over millions of years). Yet if evolution is truly an unguided process, then human brains are not designed to discover truth, and we really have no reason to trust any conclusions our brains come up with–including the conclusion that naturalism is true. So if you believe in naturalism and evolution, then you shouldn’t believe in naturalism.
Alvin Plantinga’s “Evolutionary Argument Against Naturalism,” or E. A. A. N., is the argument that, given, the conjunction of evolution by natural selection and naturalism, any person has a defeater for his or her belief in naturalism.
It can be described as P(R/N&E), where P = probability, R=the reliability of human cognitive faculties, N=Naturalism and E=Evolution by natural selection.
Naturalism + Evolution = Doubt
If Naturalism is true, then the strongest explanation for how humans came about is evolution by natural selection, either as espoused by Darwin, or else some other, similar version. As noted atheist scientist Richard Dawkins has said, Charles Darwin made it possible to be an intellectually fulfilled atheist.
However, if evolution by natural selection was an unguided, un-designed process, then humans are essentially nothing more than self-aware apes. This leads to the problem of the reliability of any belief which homo sapiens may possess. Indeed, Tom McCall has pointed out that Charles Darwin, Richard Dawkins, and Patricia Churchland have expressed doubt concerning human belief in different ways. The following are McCall’s monikers for each of the three’s expression of that conundrum.
Darwin’s Doubt: humans are merely higher-evolved monkeys, and who would trust the conclusions of a monkey about truth?
Dawkin’s Dilemma: the “watchmaker” of natural selection is a blind watchmaker, and there is no design in the universe.
Churchland’s Charmer: any traits animals may have are only there to help them with what Churchland “charmingly” calls the four Fs: feeding, fighting, fleeing, and reproduction. She says, “Truth, whatever that is, certainly takes the hindmost.”
Plantinga’s argument agrees with these three ideas, and goes like this:
- If evolution by natural selection, E, and naturalism, N, are both true, then person S has a defeater for belief
- If S has a defeater for belief, then the reliability of S’s cognitive faculties is inscrutable (this is called the Inscrutability Thesis), and S has a defeater for all her beliefs.
- N is a belief, therefore S has a defeater for N.
- The probability of N being true is therefore inscrutable (unknowable).
What Plantinga’s EAAN Shows
It is notable that Plantinga is not trying to show that the probability of naturalism is low (as some have attempted to do), but rather that on the conjunction of both N and E, there is no way of knowing how probable N is.
Plantinga does not assert that we therefore cannot trust our cognitive faculties. On the contrary, he says that we can—and this is therefore evidence for design and a designer.
Rational But Probably Unconvincing
This argument is rationally sound, though I wish it were more persuasive. It concludes inscrutability, and not low probability, for naturalism with evolution by natural selection.
At the strongest, it seems to lead to cognitive agnosticism for the non-theist. However, I doubt whether any non-theist would follow Plantinga’s line of reasoning to its logical conclusion, that he is therefore faced with the choice between distrusting his cognitive faculties or rejecting naturalism—however rational such a dilemma may be.
Plantinga’s EAAN is a good tool for the Christian to have in his toolbelt. It is a kind of presuppositional argument, in that it uncovers the presuppositions of the unbeliever’s thinking and, through a kind of reductio, demonstrates the absurdity of the unbelieving worldview. However, on its own it does not demonstrate that this particular form of unbelief (naturalism-plus-evolution) is self-contradictory
A necessary followup move, for the presuppositionalist (which Plantinga is not), would be to demonstrate that, now that belief in naturalism-plus-evolution has been shown to undermine itself, there is a better alternative. That alternative, of course, is to presuppose the truth of the Bible–specifically Genesis 1-2, in which God creates the world such that it conveys truth, and the human with a mind corresponding to the world, able to derive truth from it.
In reality, the unbeliever is actually borrowing from the truth of Genesis 1-2 in order to make his argument. In that regard, his belief in naturalism-plus-evolution actually is self-contradictory.
So the EAAN is useful, but it doesn’t quite go far enough. It just needs more #presup.