Tuesday, May 20, 2014

Do I even know anything? Alvin Plantinga's EAAN (Part 1)

"The greatest trick the Devil ever pulled was convincing the world he didn't exist."
-Verbil Kint, The Usual Suspects
Can we have the wool pulled over eyes in an extremely powerful way without having any idea of it? How correct are our ideas, if at all? Can we rely on our brains to provide us with the truth? It sure seems that way to us, but haven’t we been mistaken in important ways before? I believe, for instance, that billions of people alive today and throughout history have been wrong about their theistic beliefs ... but what ground do I have for believing that my world view is right? It seems that I must rely on the products of my cognitive faculties in reaching that conclusion, but what if they aren't reliable?!

Alvin Plantinga, arguably the most important Christian philosopher of our time, believes that naturalists are in no position to know that their beliefs are true, including the belief that naturalism itself is true. I’ll be describing his clever and interesting Evolutonary Argument Against Naturalism (EAAN) in this post and I'll be discussing my responses in the next few weeks. If you are a naturalist, you owe it to yourself to at least think about Plantinga’s argument and spend some time making sure that you have a response that you can sleep well with. If you are a theist, you’ll love how the EAAN can appear to turn the tables on us naturalists.

Naturalism (N) is notoriously difficult to define, but Plantinga defines it as the belief that there is no God, nor any being like him. Fair enough.

Naturalists tend to believe that we have arrived here according to the unguided random processes described by the Theory of Evolution (E) over billions of years. Accordingly, a question that the naturalist must ask is how E could account for faculties that deliver true beliefs.

On naturalism, a belief will be an event or structure in the brain. Here’s how Plantinga puts it:

“[A belief] will be a structure involving many neurons connected in various ways. This structure will respond to input from other structures, from sense organs, and the like; it may also send signals along effector nerves to muscles and glands, thereby causing behavior. Such a structure will have at least 2 kinds of properties: On the one hand, it will have neurophysiologic properties (NP properties) specifying, for example, the number of neurons involved in the structure, the rate of fire in various parts of it, the change of rate of fire in one part in response to a change in rate of fire in another, the way in which it is connected with other structures and with muscles, and so on. But if it is a belief, it will also have a property of a quite different sort, a mental property: It will have a content.”

Evolution will have ensured that our behavior is adaptive; if a tiger is around, it will have selected for NP properties that lead us to run away or hide. That protective behaviour increases one's chance of living another day and passing one's genes (that code for adaptive behaviour producing mechanisms, among other things) on to the next generation. But notice that it's the behaviour that is adaptive, not necessarily the belief that motivates the behaviour. If the belief content associated with adaptive NP properties is true, great, but if it’s false, that’s equally fine, so long as it leads to adaptive behaviour.

For example, Norm the Neanderthal sees a sabre tooth tiger and it occurs to him that he may be the tiger’s next meal, so he runs away and lives to tell the tale. On the other hand, Harry the Homo sapien sees a tiger and thinks that the tiger wants to scratch his back and the best way to do that is to run away. That seemingly bizarre belief content still gets him in the right place to survive; it just doesn’t matter whether it's true or false, or so argues Plantinga.

If that’s true, then the probability that a given belief is true or false is going to be roughly 0.5 at best (because truth just doesn’t matter). If someone has 100 independent beliefs, the probability that most of them, say, 75% of them, are true is going to be less than one in a million.

On naturalism and unguided evolution, therefore, the probability that our faculties will be reliable is low. It follows that we no longer have any reason to think that our faculties are reliable. If we cannot trust our faculties or the beliefs they produce, we can’t trust the belief that naturalism is true. It would be irrational for anybody who accepts Plantinga's reasoning here to continue to believe in the truth of naturalism itself; that belief, combined with E, is self-defeating.

Please note, the conclusion of the EAAN is not that naturalism is false (a de facto objection), but rather that it’s irrational to continue to believe it (a de jure objection) or anything else for that matter. Naturalism could be true, or it could be false, but since our faculties are unreliable, we just have no way of knowing either way. The EAAN concludes that we have no way of knowing anything, plunging us into the quagmire of extreme skepticism.

Here's how Plantinga clearly spells it out:

(1) On unguided evolution, the probability that our cognitive faculties will be reliable is low
(2) One who accepts unguided evolution and agrees that (1) is true, must conclude that one's cognitive faculties are unreliable.
(3) If one's cognitive faculties are unreliable, then one is in no position to believe any product of one's cognitive faculties, including the belief in unguided evolution
(4) Therefore, the belief in unguided evolution is self-defeating, and can't be rationally accepted.

Plantinga rejects naturalism: he’s a Christian theist. From his perspective, God has guided E by creating environments that select for genetic mutations that he has caused and which have made us in his image. Since God has reliable faculties, he has given us reliable faculties as well. Like magic, the skepticism that results from the combination of naturalism with E is wiped away by combining E with supernaturalism.

The greatest trick evolution ever pulled was convincing naturalists that their beliefs are true 
-Alvin Plantinga
"Keaton once said: "I don't believe in God, but I'm afraid of him" -Verbil Kint, TUS

I don't believe in God either. Maybe I should be afraid of Alvin Plantinga.

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