This paper explores evolutionary debunking arguments as they arise in metaethics against moral realism and in philosophy of religion against naturalism. Both literatures have independently grappled with the question of which beliefs one may use to respond to a potential defeater. In this paper, I show how the literature on the argument against naturalism can help clarify and bring progress to the literature on moral realism with respect to this question. Of note, it will become clear that the objection that (...) the moral realist begs the question, when appealing to the truth of some of her moral beliefs, is unsuccessful. (shrink)