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Monday, March 9, 2009

Plantinga Against Naturalism

The following is a slightly improved version of a post I recently contributed to the PhilPapers discussion forum. It is a response to Alvin Plantinga's "Evolutionary Argument Against Naturalism."

I do not know how much serious discussion among professional philosophers has been devoted to Plantinga's argument, though I know it is widely heralded by many non-professionals who do not like evolutionary theory.

Plantinga wants to use evolutionary theory to attack naturalism, but his argument fails on epistemological grounds. His error is two-fold. First, he fails to state his general epistemological position, and so leaves us wondering what he means by "truth." Second, and more detrimental to his argument, he fails to consider the possibility of epistemological behaviorism, which I take to be the most robust and compelling approach to epistemology (following the work of Peirce, Dewey, Wittgenstein, Quine, Davidson, and Rorty, to name but a few).

Consider any of Plantinga's examples of how one could survive perfectly well with a set of entirely false beliefs. One might, he says, run up a tree when confronted with a tiger, because one believed that this was the best way to pet the cute, furry animal. Thus, one's actions would lead to survival, but one would be acting on a false belief. Plantinga's point is that one could survive with a set of wholly false beliefs, and so we should not think that the possession of true beliefs is beneficial to survival.

The problem is, Plantinga makes it impossible to understand such a person's beliefs.

Let us leave aside the question of how a person could, in the course of their development, come to possess only false beliefs. (How does one only and in all cases learn to do things incorrectly? Can we imagine such a case?) This question gives us pause, but we might press forward more effectively by asking some different questions.

For example, under what conditions can we establish that a person believed one thing, and not another? What does it mean to say that the man believes the best way to pet a tiger is to run away from it? That is, in what conditions could we observe him and say, ah, yes, he believes that is how he should go about petting the tiger?

We might wonder here if the man speaks a language. If he does, then we could discuss his beliefs in terms of what he would say about his motivations, or what he says to himself about his motivations for behaving as he does. (This is how we talk about our own beliefs, after all.)

We ask the man, "Why are you running away from these tigers?" He might say, "Because I want to pet them!" How could we understand this response? We would think he was either mad, joking, or speaking a different language.

Of course, here we are assuming that the man would know what we meant by "tiger" and "running." That is, we would be assuming that the man had a relatively "true" set of beliefs, but only had a false belief about how he should behave with respect to the tiger. Yet, Plantinga's argument is that a person could have an entirely false set of beliefs. How could we communicate with such a person at all?

Let's say we supposed that the person was just speaking a different language. How could we go about translating that language? Perhaps we would be able to get to the point where we decided that, according to the person, "wanting to pet the tiger" meant "wanting to escape" or perhaps "wanting to run up the tree," or some such. In that case, we would not say the person's beliefs were false at all. For us to conclude that all of their beliefs were false, we would have to be able to interpret their beliefs as contradicting their behavior in all cases, and that precludes the possibility of any effective translation of their language into our own. Thus, such a person as Plantinga describes would always seem to be talking nonsense.

One might try to defend Plantinga's argument by defining beliefs as distinct from what a person can say about them. Beliefs, then, are not propositional attitudes, but perhaps attitudes towards some kind of mental state(s). Perhaps beliefs are attitudes towards mental images.

Imagine a person forming an image of what it would be like to pet a tiger, and then acting on the image by running up a tree and waiting for the tiger to go away. In what sense is that acting on the image?

A person without language can be said to be acting on a belief, in so far as they are acting according to a representation of the world. But in Plantinga's hypothetical scenario, how are any such images actual representations of the world? They cannot correspond with anything the person does, or else we would say they were "true" images.

Try to consider always acting on images which in no way corresponded with lived experience. A person could not learn (could not produce new images) based on one's experiences, or else some sort of correspondence would have to be at work. One could thus not respond effectively to novel situations. One could not even come to a rational understanding of their lived experience. Their experience itself would be a liability, as it would always seem to interfere with the images in their mind. Such a person would be living in a perpetual, debilitating state of cognitive dissonance.

We clearly have no way of understanding how a person could function as Plantinga describes, whether or not we stipulate that the person in question uses language or merely images.

This is a fatal flaw in Plantinga's argument, but it does not fully counter the intuition which Plantinga and his supporters maintain: namely, that evolutionary theory cannot account for truth. To uncover the full depth of Plantinga's error, we have to look at just how evolution could have selected for truth. That is, we must come to a more feasible notion of true belief.

And here it is quite simple: for we have no trouble understanding how evolution could select for the ability to develop and utilize various tools, and why not think that language is such a tool? If we think of language as a tool for furthering our successful reproduction, we can regard the category of "truth" as one aspect of that tool. Specifically, it is that aspect of the tool which turns language upon itself in a process of evaluation. "Truth" is what we call language when it works for certain ends.

Evolutionary theory does not say that our only end is reproduction; rather, it says that our ability to reproduce explains why we are the way we are. Our ends can thus be at least partially explained in terms of reproduction without being reduced to them. And so we can talk about truth without talking specifically about what will or won't lead to reproduction.

The main point here is that truth is a matter of what works, and that is all a matter of behavior. This is why we could not possibly understand the beliefs of somebody such as Plantinga describes, and why we should have no problem acknowledging our evolutionary origins whilst rejecting supernaturalism.