Lecture Series: Lecture 8: Plantinga's Evolutionary Argument Against Naturalism

Alvin Plantinga is an important Christian philosopher, formerly with the University of Notre Dame. We will soon consider his "free will defense" as a solution to the problem of evil. We also have noted his ontological argument for God's existence. Now we turn to his critique of naturalism, referred to simply as the EAAN argument--the Evolutionary Argument Against Naturalism.

Since this is to be a brief summary, I'll start with the end of the argument and work backwards. If naturalism is true, then the human mind is a biochemical machine thrown together by chance, the product of random genetic drift over time. Such a mind cannot be relied upon to produce true beliefs about the world, including the belief that naturalism is true. Thus naturalism is an "undercutting defeater" of itself.

What does evolution ensure? Does it guarantee that we will develop true beliefs about the world, ourselves, God, etc.? No, evolution at best ensures only that we survive, but it is not obvious that survival is dependent on true beliefs. The philosopher Patricia Churchland puts it bluntly, "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… Truth, whatever it is, takes the hindmost (back seat).” The point here is that true beliefs are largely irrelevant to survival, or are at the very least totally superfluous to it.

Consider the two statements, "survival is the goal of all living creatures," and "survival is not the goal of all living creatures--understanding is." Why should we believe that our ancestors, who perhaps taught us that understanding is the goal of life, are not wholly in the wrong? Is there anything in evolutionary theory to suggest to us that either opinion recommends itself over the other?

The illustration Plantinga uses to back his thesis is simple and effective. It is probable that primitive cavemen ran away from Tigers. But why? Did they run away from them because their beliefs about Tigers were true beliefs? It is at least conceivable that the first human beings ran away from Tigers because they wanted to pet them and believed that running away was necessary to draw them nearer. They could have believed that the appearance of the Tiger indicated the beginning of a race. They could have believed the Tiger was a demon of hell and must be avoided at all costs. Perhaps the first caveman believed the Tiger was a regularly recurring illusion, and, wanting to keep his weight down, decided to run a mile every time the illusion appeared. Perhaps the first caveman confused running toward it with running away from it. His behavior was sufficient to ensure his survival even though his beliefs were wholly in the wrong.

Other examples of this phenomenon are myriad. For example, we know that our beliefs about the earth, the universe and our relationship to it are constantly updated by scientific discoveries. And the curious thing is that primitive man, with so little knowledge about the nature of the world, somehow survived. In what way did knowledge of the earth's spherical shape increase our ability to survive? In point of fact, the human belief that the earth was flat could have prevented a lot of deaths because it kept men safely ashore during a period when sea travel was quite dangerous.

Plantinga's argument briefly summarized then:

The probability of the accuracy of human reason is low or inscrutable (unknowable) given...

A. Chance production of the mind.

B. Evolution ensures survival but not true beliefs.

C. Conclusion: Therefore, since there is a low probability that human reason can be relied upon to produce true beliefs, and two of the conclusions of human reason are naturalism and evolution, then we can doubt both.

Another angle at Plantinga's argument is to consider the matter from the perspective of Hume and Darwin combined. As I have discussed in other blog entries, Hume asserts that causation itself could be manufactured by our intellect subjectively rather than existing as an objective feature of the world. In other words, it is very possible that the universe is a random collection of events and that we impose causal relations on events that merely succeed one another but do not determine each other in any measurable fashion. Then Darwin comes along and provides humanists with a reason to believe that the world is, in reality, a random collection of events, and the mind is a product of nothing more than luck. But if the atheist is looking for some reason to believe that there is any pattern to how and why things happen in the world, surely he has not only given up any hope of finding it, but has answered his question by diffusing the value and import of all questions.

In the end, all Darwinian and Neo-Darwinian Evolution end up saying is that random changes in an environment meet random changes in organisms. When there is a lucky correspondence, the organism survives. But what could be more irrelevant to any life-form in those circumstances than true beliefs, including the belief that these conditions are lucky, or the belief that these conditions are ordained? Darwin himself said it this way: “The horrid doubt always arises whether the convictions of man’s mind, which has been developed from the mind of the lower animals, are of any value or at all trustworthy. Would any one trust in the convictions of a monkey’s mind, if there are any convictions in such a mind.”