Abstract

More than a century ago, G. E. Moore famously offered an extended inference to reject what are in effect two substantially different types of ethical naturalism. Although some naturalistic doctrines targeted by that inference make semantic claims that, if true, would entail certain metaphysical claims, it is also possible that those semantic doctrines could be false and the metaphysical ones true at the same time. For if semantic naturalism is true, then moral terms and sentences are reducible, by an analysis of what they mean, into some purely descriptive terms and sentences. But, if metaphysical naturalism is true, then the moral properties and propositions expressed by moral terms and sentences are reducible to purely natural properties and propositions. By conflating claims about meaning with claims about reference, Moore‟s original inference proved vulnerable to a number of well known objections. But we believe there is a revised Moorean inference that can succeed, and we offer that argument here. Its scope is restricted to semantic reductivist forms of ethical naturalism: those that rest on theses claiming the reducibility of expressions in the moral vocabulary to expressions in a non-moral one. A not uncommon philosophical view in Moore‟s day, such theses remain live options in metaethics (as we‟ll presently show). Although our inference is run for some putative equivalences between moral and purely descriptive terms, it could easily be adapted against ethical naturalist theses 1 involving moral concepts and thoughts as well as sentences. Like Moore, we take the successful inference to consist in an open question argument („OQA’) followed by the naturalistic-fallacy charge („NFC‟). But, unlike Moore, we identify semantic naturalism as the only naturalistic doctrine vulnerable to the inference, and we offer adequate support for the inference‟s premises. Naturalism in ethics is thus undermined, though not refuted in all its forms: semantical naturalism comes out false, but metaphysical naturalism might still be true..