To those unfamiliar with Alvin Plantinga’s evolutionary argument against naturalism the idea evolution could even conceivably undermine naturalism, when it’s generally considered one of the important pieces in naturalism, may seem a lot peculiar. However, if Plantinga’s argument is right then evolution does indeed undermine naturalism, here defined by Plantinga simply as the philosophical position that “there is no such person as God.” The idea in contention is if an unguided evolutionary process could result in “the great bulk” of our beliefs being true or our cognitive faculties being reliable, he claims it’s not probable or at least less probable than traditional theism, meaning essentially the Abrahamic god. God, if it existed, could easily guide evolution such that our cognitive faculties are reliable.
Plantinga claims the problem is in an unguided process of evolution even if beliefs effect actions, something he doesn’t concede is necessarily true in naturalism, evolution doesn’t select for true beliefs it selects for beliefs that produce adaptive behavior. A human could avoid being eaten by a tiger by correctly believing it as a threat and running away or by wanting to pet it and believing the best way to do so is to run away. Either way the adaptive behavior of running away would be selected for meaning false beliefs could be selected for and this is but one alternative way beliefs could be related to behavior. This, by the way, is already misleading because individual beliefs are not selected for, cognitive faculties which produce beliefs are as there are no genes for individual beliefs. Any geneticist could have told him this but I digress…
He presents his argument as Bayesian but, for clarity, and for my purposes it will suffice as a syllogism:
- Naturalism is true and we evolved.
- Evolution (primarily) selects for behavior adaptive behavior.
- False or arbitrary beliefs can generate adaptive behavior.
- Therefore there’s no (good) reason to suspect true beliefs will be selected for through evolution.
- Therefore there’s no reason to believe “the great bulk” of are beliefs are true.
- Therefore if we evolved there’s no reason to believe we evolved (or anything in particular).
So, he would say, the belief that naturalism and evolution are both true refutes itself so we must adopt traditional theism. Setting aside the patently ridiculous idea that the only options are the types of theism present in depictions of the Biblical god and naturalism with evolution, there’s still a host of problems with this reasoning. Yes, Plantinga is correct that it’s not logically impossible that false or arbitrary beliefs could produce adaptive behavior but this doesn’t mean it would happen in reality. What’s conceivably possible, however vanishingly improbable, isn’t what the theory of evolution is about. This is why, as his critics Fitelson and Sober point out, zebras didn’t evolve to create machine guns in response to the threat of lions. Evolution acts on what’s available, not on all logical possibilities so compiling a litany of logically possible scenarios with no mention of how probable they each are but saying combined they are more probable than any given one scenario, as he does, isn’t probabilistic reasoning it’s fallacious reasoning.
More directly the idea that correct modeling and true beliefs serve no survival advantage is not just wrong, it’s ludicrous. This is likely based on the erroneous, and unstated, assumption that evolution happens in a single static environment because unless that is the case those with arbitrary or false beliefs would have to out compete with those with correct models of the world for generating true beliefs. Those with arbitrary or false beliefs, like the best way to pet the tiger is to run away from it, wouldn’t survive if they had to compete with individuals who could model reality and as a result come to new true beliefs in the ever-changing environment. Even within a single generation the advantage of being able to adapt to new situations or learn new rules is huge but only those with a reliable way for generating new adaptive beliefs would gain from this. There’s just no way this could plausibly be faked with a set of individually attained arbitrary or false beliefs. Possibly only in the bizarre scenario in which an agent is always wrong but always infers the opposite of what it should from that wrong belief is it even conceivably feasible.
Additionally how the traditional theist god, and only that being, is supposed to get us out of this conundrum of explaining why our cognitive faculties are reliable is unexplained. Surely one could propose theism in which god tries to deceive humans or intentionally made us irrational. Scenarios like this can’t be eliminated out of hand because, unlike evolution, talk of theism, if it is ever coherent, is about all that is logically possible because there’s no empirical way to test any idea. As a result the appeal to traditional theism to solve this problem isn’t just improbable, it would be just one of an infinite number of unverifiable scenarios. All this means that not only has Plantinga’s argument failed to demonstrate evolution makes naturalism implausible but the appeal to a specific unknowable god is inherently extremely improbable. In other words this isn’t a threat to naturalism and even if it was it couldn’t demonstrate, or even make probable, the existence of the traditional theist god.