Two kinds of naturalism in ethics

What are the conditions on a successful naturalistic account of moral properties? In this paper I discuss one such condition: the possibility of moral concepts playing a role in good empirical theories on a par with those of the natural and social sciences. I argue that Peter Railton’s influential account of moral rightness fails to meet this condition, and thus is only viable in the hands of a naturalist who doesn’t insist on it. This conclusion generalises to all versions of naturalism that give a significant role to a dispositional characterisation of moral properties. I also argue, however, that the epistemological and semantic motivations behind naturalism are consistent with a version of naturalism that doesn’t insist on the explanatory condition. The conclusion is that those naturalists who are attracted to accounts of moral properties such as Railton’s would do better not to insist on this\break condition.