  It might be tempting to say that moral naturalism should, properly understood, consist in the conjunction of Epistemic, Metaphysical, and Analytic Naturalism. But that suggestion would be unacceptable, as there is a strong tension between Epistemic Naturalism and Analytic Naturalism. If Analytic Naturalism is true, then it should be possible (at least in principle) to go through a process of conceptual analysis that would reveal the synonymy between moral claims and claims in the natural sciences. But if this is possible, then substantive moral principles are knowable a priori—which, in turn, entails that substantive moral principles are not known in the same way as scientific principles. Analytic Naturalism therefore seems to entail that Epistemic Naturalism is false, and vice versa. Naturalists who accept Analytic Naturalism are called, appropriately enough, analytic naturalists. Naturalists who reject Analytic Naturalism are synthetic naturalists, since they hold that claims regarding relations between the moral and the natural are synthetic rather than analytic.