In Chapter 2 of Taking Morality Seriously, I put forward an argument for morality's objectivity that is based on the first-order implications of denying such objectivity. In her contribution to this volume, Mancuso criticizes that argument. This paper is a response to some of her main points.

David Enoch has recently proposed that the deliberative indispensability of irreducibly normative facts suffices to support their inclusion in our ontology, even if they are not necessary for the explanation of any observable phenomena. He challenges dissenters to point to a relevant asymmetry between explanation and deliberation that shows why explanatory indispensability, but not deliberative indispensability, is a legitimate guide to ontology. In this paper, I aim to do just that. Given that an entity figures in the actual explanation of (...) some phenomenon, it is not an open question whether that entity exists. Thus, if you can manage to find actual explanations, you can find answers to ontological questions. In contrast, even if some entity is indispensable to deliberation, it still might not exist. For example, even if some form of libertarian free will is deliberatively indispensable, we still might not have libertarian free will. So even if you manage to discover the indispensable commitments of deliberation, there is still more work to do to get to the bottom of things. That additional work is explanatory work, and so deliberative indispensability is not an independent guide to what there is. (shrink)