Moral epistemology, like general epistemology, faces a regress problem. Suppose someone demands to know why I am justified in holding a moral belief. In a typical case, I will respond by citing a further moral belief that justifies it. A regress arises because, in order for this further belief to justify anything, it too must be justified. According to a traditional position in moral epistemology, moral foundationalism, the regress comes to an end with some moral beliefs. Moral foundationalism is an attractive position because it promises to answer the regress problem. However, it inherits the burden of explaining why some moral beliefs have a particular privileged epistemic position – that is, why these beliefs are justified without requiring inferential support from other beliefs. The standard answer to this question is to insist that some moral beliefs have as their content propositions that are self-evident.
A common way of resisting moral foundationalism is to argue from the fact of moral disagreement to the claim that no moral proposition is self-evident. I argue that while a simple version of this argument fails, this argument can be developed in such a way that it poses serious difficulties for moral foundationalism. I develop this argument by drawing on recent work in epistemology on the nature of our epistemic burdens in the face of peer disagreement. I then suggest that even if this argument does show that moral foundationalism fails, it need not have skeptical implications so long as coherentism remains a viable option in moral epistemology. Finally, I claim that this argument has implications for normative ethics. Namely, it rules out a position advocated by Peter Singer in his early work and indirectly supports the method of reflective equilibrium.