Ever since evolution by natural selection was conceived of, there have been worries that an evolutionary account of our intuitions will undermine the credibility of those intuitions. (The early worries were about moral intuitions, but the worry generalizes to all intuitions)

For example, take the intuition that we have reason to think our sense-impressions resemble an external world.

Well, if there actually is an external world that resembles the content of some sense-impressions, then clearly a reproductive advantage would be enjoyed by those whose sense-impressions did resemble the world and whose intuition told them that they have reason to believe this.

But we do not need to posit reasons to believe anything in order for this explanation to work (or so the worry goes). We need to posit an external world and sensory faculties that generate sense-impressions whose content resembles the world. And that, combined with evolution by natural selection, will generate creatures like us: creatures who have intuitions that tell them to believe their sense-impressions are 'of' a world.

Well, if we do not need to posit any reasons to believe things, then Ockham's razor tells us not to do so.

The problem, however, is that this now means we have no reason to believe that there's an external world or that the theory of evolution by natural selection is true and no reason to believe anything I just argued.

Any argument - any case - that ends by concluding that we do not have any reason to believe anything is self-undermining. For arguments are just attempts to show us what we have reason to believe.

We can safely dismiss such arguments, then. They are, in effect, arguments against arguments. Only a fool or a scoundrel makes an argument against arguments.

But now we have a puzzle. We cannot - without being a fool or a scoundrel - deny the reality of reasons to believe things. And so we have to admit that our intuition - which is the means by which we are aware of reasons to believe things - tells us about something real. Yet a purely evolutionary story about how we developed a faculty of intuition tells us that what they are telling us about - reasons to believe things - are not real at all, but just things it was adaptive for our ancestors to believe in.

Does this mean we must conclude that evolution by natural selection is false? No, it just means it cannot be all encompassing. Again: any case for thinking it is all encompassing is actually a case against cases, and thus is the case of a fool. For again: if you think it is all encompassing, then it turns out that there are no reasons to believe anything, which means there's no reason to believe evolution by natural selection is true!

But in what way does the account need supplementing? Well, the case for evolution by natural selection presupposes that there are reasons to believe things. And reasons to believe things require God. Sorry, but they do. So the case for evolution by natural selection presupposes that God exists. And it is this that shows how it could come to pass that we have a faculty of intuition that tells us about reasons to believe things. For the world that evolution by natural selection posits is a place that is deadly dangerous. It quickly kills those who fail to navigate it well. Well, wouldn't a good person try and warn people about those dangers? Wouldn't they equip those they know are living there - or destined to live there - with a faculty of intuition that would tell them how best to make use of their sensible faculties so as to be able to navigate the world more safely? I think so. Seems reasonable. And of course, those who are equipped with such a faculty will, if it is reliable and they trust it, be selected for as the world won't kill them as quickly as it does others.

In this way, I think, we can explain why we can trust - or at least, default trust - our intuitions. Evolution by natural selection presupposes that there is an external world in which such forces of selection are operating and that we are, in some sense, 'in' it. But it also presupposes that there are reasons to believe things and thus presupposes God. And it is with those presuppositions that it gets the job done. But if you try and do without God, then the theory undermines itself as it undermines the epistemic status of all our intuitions, including those that the case for evolution by natural selection appeals to.