David Brink has recently argued for the “parity” of ethics and the sciences. While the parity claim alone might be metaphysically neutral, Brink favours a form of ethical naturalism on which moral properties “are” natural properties, just as non-moral macrophysical properties “are” the microphysical states that compose them. Brink supports this claim by showing that both types of properties share certain important features: specifically, that both may be constituted, supervening and synthetically necessitated. I shall argue that notwithstanding these common features, (...) there remain significant modal differences in the way the two types of properties are assigned to the world. These differences represent an important respect in which moral properties are not on par with their scientific counterparts. (shrink)

David Brink, in his book Moral Realism and the Foundations of Ethics, and other writers, have recently offered powerful new arguments for a form of moral realism that sees moral inquiry as being "on par" with scientific inquiry in many important epistemological and metaphysical respects. I call this theory "Assimilative Moral Realism" . AMR is marked by naturalism about moral facts, and by empiricism about moral knowledge. Moral facts are held to be facts about properties that are constituted by, and (...) supervene upon, complexes of ordinary natural and social properties, just as certain scientific facts are facts about the macrophysical properties that are realized by certain microphysical bases. Moral beliefs are held to be justifiable in the way certain scientific beliefs ostensibly are: via certain explanatory inferences and indirect empirical tests of moral principles. Further, traditional semantical objections to naturalistic moral realism can be avoided, it is supposed, because semantical tests for the existence of moral facts can plausibly be rejected, just as they can be in the scientific case. In this thesis, I make a case for rejecting this assimilative theory. I provide a number of technical reasons to suppose that moral principles cannot be tested empirically using the Duhemian method advocated by AMR theorists. I also give a critique of their main arguments for the relevance and indispensability of assumptions about moral facts to explanations of moral judgments and other items, and conclude that their arguments establish neither the explanatory relevance nor necessity of moral assumptions. Finally, in place of the AMR theory of supervening moral properties, I offer an account of moral supervenience claims--an account that is itself compatible with AMR only if there are sound moral explanations of certain nonmoral facts. (shrink)