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3.4.04

Evolving A Belief In Evolution

Joe Carter has a couple posts up recapping an argument by Alvin Plantinga (though anticipated, in a moment of self-doubt, by Darwin) that basically says that if our brains had evolved by purely natural processes, we couldn't trust them to tell us the truth about evolution. (I'm posting this now based just on Carter's explanation because if I wait to read Plantinga's full argument, I'll never get around to it.) The outline of the argument is:

1. If (naturalistic) evolution is true, then our cognitive faculties will have resulted from blind mechanisms like natural selection, working on sources of genetic variation such as random genetic mutation.
2. Assuming the truth of #1, we find that the ultimate purpose or function of our cognitive faculties, if they even have a purpose or function, will be survival - of individual, species, gene, or genotype.
3. If #1 and #2 are true then it is unlikely that our cognitive faculties have the production of true beliefs as a function.
4. If production of true beliefs is not a function of our cognitive faculties, we have no reason to trust that we can form true beliefs.
5. Therefore, we cannot claim that any belief, including a belief in the theory of macroevolution, is true.


The obvious response (interestingly similar to the defense of pragmatism as a philosophical methodology, given that pragmatism's heyday was a time when evolutionary biology was the model science) is that true beliefs have a survival value. Carter uses a story about Zed, the first Homo sapiens, to show how beliefs can have survival value without being true:

In order to survive, Zed needs to act in certain ways in order to survive. For example, he needs to avoid the saber tooth tiger taking a bite out of his big brain. We’ll call this behavior B for “tiger avoidance behavior.” Now B could be produced by Zed’s desire not to get eaten plus the true belief that B will increase his chances of not having his brain eaten.

The problem is that B could be produced by false beliefs as well. Perhaps Zed likes the idea of being eaten and wants to run toward the tiger. But Zed always confuses running toward with running away from tigers. His false belief actually aids his survival. Therefore it is possible that beliefs could have a survival advantage and yet be false.


The problem here is that we're dealing with specific individual beliefs. In such a case, it's easy to think of alternate beliefs that could produce action just as beneficial. However, that's not how the human brain works. What we have evolved is not beliefs but a belief-producing apparatus. When considering belief-producing apparatuses, it becomes less likely that they can consistently produce beneficial outcomes by a mechanism other than determining the truth about the situation. Our apparatus isn't perfect -- see Kahneman and Tversky's work on biases and heuristics -- but it's hardly surprising that evolution would be a work in progress. But it is well-developed enough that we can turn it back on itself, testing and refining our use of it so that we can get better results.

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