Alvin Plantinga is one of those philosophers that the ID crowd likes to name-drop when attempting to justify their positions. Recently, he published a short five-page essay entitled "Evolutions vs. Naturalism," and subtitled, “Why they are like oil and water.” The gist of the essay, obviously, is that Plantinga thinks that evolutionary theory is the downfall of philosophical naturalism. He writes, “Evolutionary naturalism, therefore—the belief in the combination of naturalism and evolution—is self-refuting, self-destructive, shoots itself in the foot.” Some of you reading this might find this puzzling and wonder just how Plantinga’s argument works. After all, evolutionary theory is often considered to be the metaphorical final trumpet call of naturalism defeating other ontologies (though, personally, I would suggest some caution before sounding the victory), certainly not its refutation. I’ll do my best to explain Plantinga’s position before making the case that he is wrong.
Here is how Plantinga’s argument goes: First, Plantinga says that naturalists are materialists. That means that our beliefs are just neurochemical reactions, wholly material with no input available from anything outside purely naturalistic means. Next, he says that evolutionary theory explicitly says that it is our behavior that is adaptive in that our ancestors were those whose behavior was adapted to leave behind offspring that survived. So what we have now are brains that produce behaviors that are adaptive. These brains, then, are what cause beliefs, meaning that beliefs are purely the function of some neurophysiology that is the result of evolutionary pressure to produce behaviors that result in organisms who leave behind offspring who leave behind offspring, etc. So far, so good. Now, here is where the “problem” arises. Plantinga says there is nothing within this system that cares a whit as to whether or not those beliefs are, in fact, true. All that matters is that they are adaptive. As such, there is no guarantee that they are right, but only that they proved successful. Here, he quotes Patricia Churchland when she writes:
Boiled down to essentials, a nervous system enables the organism to succeed in the four F’s: feeding, fleeing, fighting and reproducing. The principal chore of nervous systems is to get the body parts where they should be in order that the organism may survive … . Improvements in sensorimotor control confer an evolutionary advantage: a fancier style of representing is advantageous so long as it is geared to the organism’s way of life and enhances the organism’s chances of survival [Churchland’s emphasis]. Truth, whatever that is, definitely takes the hindmost.
From this Plantinga concludes, “What [this] tells us is that the neurophysiology that produces those beliefs is adaptive, as is the behavior caused by that neurophysiology. But it simply doesn’t matter whether the beliefs also caused by that neurophysiology are true. If they are true, excellent; but if they are false, that’s fine too, provided the neurophysiology produces adaptive behavior.” Because of this, assuming evolutionary theory is right, we have no reason to think that any of our beliefs are true at all. And if this is right, we don’t even have a good reason to think that evolutionary theory is right. All we are left with is a deep and pervasive skepticism. Plantinga writes:
If evolutionary naturalism is true, then the probability that our cognitive faculties are reliable is also very low. And that means that one who accepts evolutionary naturalism has a defeater for the belief that her cognitive faculties are reliable: a reason for giving up that belief, for rejecting it, for no longer holding it. If there isn’t a defeater for that defeater—a defeater-defeater, we could say—she can’t rationally believe that her cognitive faculties are reliable. No doubt she can’t help believing that they are; no doubt she will in fact continue to believe it; but that belief will be irrational. And if she has a defeater for the reliability of her cognitive faculties, she also has a defeater for any belief she takes to be produced by those faculties—which, of course, is all of her beliefs. If she can’t trust her cognitive faculties, she has a reason, with respect to each of her beliefs, to give it up. She is therefore enmeshed in a deep and bottomless skepticism. One of her beliefs, however, is her belief in evolutionary naturalism itself; so then she also has a defeater for that belief. Evolutionary naturalism, therefore—the belief in the combination of naturalism and evolution—is self-refuting, self-destructive, shoots itself in the foot. Therefore you can’t rationally accept it. For all this argument shows, it may be true; but it is irrational to hold it. So the argument isn’t an argument for the falsehood of evolutionary naturalism; it is instead for the conclusion that one cannot rationally believe (emphasis his) that proposition. Evolution, therefore, far from supporting naturalism, is incompatible with it, in the sense that you can’t rationally believe them both.
So where does this leave us? Is Plantinga right? Does evolutionary theory really rule out naturalism? I don’t think so. First, it just doesn’t seem to be the case that evolutionary pressure is the basis for most of our beliefs. Certainly, some of them might be hardwired into us and, thus, the direct result of evolution. Some obvious examples might be that snakes are dangerous (study has shown that it is very difficult to make most people comfortable with snakes, even those that aren’t dangerous to humans), flowers are safe (it just turns out that it’s difficult to condition most people to be afraid of flowers, even those that are poisonous), that loud noises indicate danger, and things like that. But cases like these don’t seem to be the bulk of our everyday beliefs. For those we need to look at the behavior that underlies belief-formation. Then the question becomes this: Is it likely that a process that systematically creates false beliefs will be adaptive? Here the answer just seems to be “no.” If I have some behavioral system that is responsible for generating the majority of my everyday beliefs- those that aren’t hardwired into me- and if that system is put together in such a way that the bulk of those beliefs are wrong, how could it possibly work that such beliefs would result in my successful navigation of the world such that I would be likely to leave behind offspring who share my behavior of systematically generating false beliefs?
Let’s look at some of the examples that Plantinga offers in terms of false beliefs that are adaptive. In Warrant and Proper Function, Plantinga suggests a scenario that involves a hominid Paul and a hungry tiger. In such a case the proper behavior (in terms of success defined as surviving long enough to produce offspring who survive) is to run away from the tiger. But, several different beliefs could result in such behavior:
Perhaps Paul very much likes the idea of being eaten, but when he sees a tiger, always runs off looking for a better prospect, because he thinks it unlikely that the tiger he sees will eat him. This will get his body parts in the right place so far as survival is concerned, without involving much by way of true belief. . . . . Or perhaps he thinks the tiger is a large, friendly, cuddly pussycat and wants to pet it; but he also believes that the best way to pet it is to run away from it. . . . or perhaps he thinks the tiger is a regularly recurring illusion, and, hoping to keep his weight down, has formed the resolution to run a mile at top speed whenever presented with such an illusion; or perhaps he thinks he is about to take part in a 1600 meter race, wants to win, and believes the appearance of the tiger is the starting signal; or perhaps . . . . Clearly there are any number of belief-cum-desire systems that equally fit a given bit of behavior.
This kind of behavior fits nicely with the earlier description that I gave of hardwired beliefs which might be adaptive, but it does not in any way address the question of how a system that consistently generates false beliefs could be adaptive. In fact, from what I’ve seen, Plantinga never addresses this issue, and it is not hard to see why. There is no good way to explain why any process that generates many false beliefs would be likely to be adaptive in any significant sense. A mechanism that produces false beliefs might cause a specific adaptive behavior (e.g. running from the Tiger because you believe it is the signal to start a race), but there is no good reason to believe that the same mechanism that generates one accidentally adaptive false belief will produce consistently adaptive behaviors. Such a mechanism would produce an enormous variety of beliefs, mostly false and incoherent, and those beliefs would, in turn, produce behaviors which were in no way tied to the external world. There is just no way for such a system to engender the success and survival of some organism.
Plantinga goes wrong in that he never considers that we do not arrive at the majority of our beliefs by way of some specific evolutionary pressure. Rather, most of our beliefs are the result of a belief-generating mechanism. It is the mechanism, then, that is adaptive, and the beliefs that fall out of it must produce behaviors that allow us to successfully navigate the world. While it might be the case that specific false beliefs could lead to behavior that is adaptive, it seems highly unlikely that a system which produces beliefs that influence behaviors that were not themselves the result of evolutionary pressures could systematically produce false beliefs which still helped the organism survive.
There is, of course, the larger issue from which Plantinga suffers in that he presumes that if God created us, then we can trust that our beliefs are true, but I’ll save that for another day.