In the past, I’ve been a bit reluctant to comment on Plantinga’s “evolutionary argument against naturalism” (EAAN). Plantinga has a long history of refusing to get his science right when writing about science, and when philosophers do that part of me feels our only response should be to point out what they’re doing and say, “come back when you’re not screwing up your science and then we can talk philosophy.”
But in any case, Stephen Law has just put up a blog post with a journal article published he published in Analysis last year. Here’s Law’s summary of his case:
Plantinga argues that if naturalism and evolution are true, then semantic epiphenomenalism is very probably true – that’s to say, the content of our beliefs does not causally impinge on our behaviour. And if semantic properties such as having such-and-such content or being true cannot causally impinge on behaviour, then they cannot be selected for by unguided evolution. Plantinga’s argument requires, crucially, that there be no conceptual links between belief content and behaviour of a sort that it’s actually very plausible to suppose exist (note that to suppose there are such conceptual links is not necessarily to suppose that content can be exhaustively captured in terms of behaviour or functional role, etc. in the way logical behaviourists or functionalists suppose). It turns out that if such conceptual links exist, then (rather surprisingly!) natural selection will favour true belief even if belief content is epiphenomenal. So Plantinga is mistaken: even if belief content has no causal impact on behaviour, natural selection can still select for true belief. The EAAN is therefore refuted. To resurrect the EAAN, Plantinga would need to show that there no conceptual links of the sort I envisage between content and behaviour, links of a sort that, as I say, do seem to exist.
I’ve had more or less this thought before, but I think it can be put even more simply. As I wrote at the beginning of this year: “As far as I can tell, [Plantinga's argument] makes no more sense than saying that if materialism were true, it is by virtue of the arrangement of subatomic particles that our digestive system digests food, and therefore whether or not those particles are arranged into a stomach, intestines, etc. is irrelevant with respect to digestion, and therefore evolution is unlikely to produce those organs.”