Against Normative Naturalism

This paper considers normative naturalism, understood as the view that (i) normative sentences are descriptive of the way things are, and (ii) their truth/falsity does not require ontology beyond the ontology of the natural world. Assuming (i) for the sake of argument, I here show that (ii) is false not only as applied to ethics, but more generally as applied to practical and epistemic normativity across the board. The argument is a descendant of Moore's Open Question Argument and Hume's Is-Ought Gap. It goes roughly as follows: to ensure that natural ontology suffices for normative truth, there must be semantically grounded entailments from the natural truths to the normative truths. There are none. So natural ontology does not suffice for normative truth.