 In  section 3.2,  we introduce the distinction between normative realism and normative anti-realism. We sketch the challenge that our question poses to normative realism, and the kinds of answers that realists might provide. Realism is, however, compatible with fundamentally different views about the explanation of normativity. In  section 3.3,  we consider the “primitivist” view that the nature of normativity cannot be explained at all, at least not in non-normative terms. Primitivism is characteristic of non-naturalism, but it is also available to naturalists.