Zebras with Machine Guns

I was just rereading some of the literature on Plantinga’s Evolutionary Argument Against Naturalism (EAAN) as a distraction from trying to write too much on ¡Reconquista!, since it looks like I am on a much faster trajectory to finishing the book than I had thought. EAAN is a curious little argument that some have dismissed as a resurgent example of scholastic theology. It has some newer trappings that we see in modern historical method, however, especially in the use Bayes’ Theorem to establish the warrant of beliefs by trying to cast those warrants as probabilities.

A critical part of Plantinga’s argument hinges on the notion that evolutionary processes optimize against behavior and not necessarily belief. Therefore, it is plausible that an individual could hold false beliefs that are nonetheless adaptive. For instance, Plantinga gives the example of a man who desires to be eaten by tigers but always feels hopeless when confronted by a given tiger because he doesn’t feel worthy of that particular tiger, so he runs away and looks for another one. This may seem like a strange conjunction of beliefs and actions that happen to result in the man surviving, but we know from modern psychology that people can form elaborate justifications for perceived events and wild metaphysics to coordinate those justifications.

If that is the case, for Plantinga, the evolutionary consequence is that we should not trust our belief in our reasoning faculties because they are effectively arbitrary. There are dozens of responses to this argument that dissect it from many different dimensions. I’ve previously showcased Branden Fitelson and Elliot Sober’s Plantinga’s Probability Arguments Against Evolutionary Naturalism from 1997, which I think is one of the most complete examinations of the structure of the argument. There are two critical points that I think emerge from Fitelson and Sober. First, there is the sober reminder of the inherent frailty of scientific method that needs to be kept in mind. Science is an evolving work involving many minds operating, when at its best, in a social network that reduces biases and methodological overshoots. It should be seen as a tentative foothold against “global skepticism.”

The second, and critical take-away from that response is more nuanced, however. The notion that our beliefs can be arbitrarily disconnected from adaptive behavior in an evolutionary setting, like the tiger survivor, requires a very different kind of evolution than we theorize. Fitelson and Sober point out that if anything was possible, zebras might have developed machine guns to defend against lions rather than just cryptic stripes. Instead, the sieve of possible solutions to adaptive problems is built on the genetic and phenotypic variants that came before. This will limit the range of arbitrary, non-true beliefs that can be compatible with an adaptive solution. If the joint probability of true belief and adaptive behavior is much higher than the alternative, which we might guess is true, then there is a greater probability that our faculties are reliable. In fact, we could argue that using a parsimony argument that extends Bayesian analysis to the general case of optimal inductive models (Sober actually works on this issue extensively), that there are classes of inductive solutions that, through eliminating add-ons, outperform predictively those solutions that have extra assumptions and entities. So, P(not getting eaten | true belief that tigers are threats) >> P(not getting eaten | false beliefs about tigers), especially when updated over time. I would be remiss if I didn’t mention that William of Ockham of Ockham’s Razor-fame was a scholastic theologian, so if Plantinga’s argument is revisiting those old angels-head-pin-style arguments, it might be opposed by a fellow scholastic.

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