T. M. Scanlon offers a qualified defense of normative cognitivism--the view that there are irreducibly normative truths about reasons for action. He responds to three familiar objections: that such truths would have troubling metaphysical implications; that we would have no way of knowing what they are; and that the role of reasons in motivating and explaining action could not be explained if accepting a conclusion about reasons for action were a kind of belief. Scanlon answers the first of these objections within a general account of ontological commitment, applying to mathematics as well as...