Are the Moral Fixed Points Conceptual Truths?

Terence Cuneo and Russ Shafer-Landau have recently proposed a new version of moral non-naturalism, according to which there are non-natural moral concepts and truths but no non-natural moral facts. This view entails that moral error theorists are conceptually deficient. We explain why moral error theorists are not conceptually deficient. We then argue that this explanation reveals what is wrong with Cuneo and Shafer-Landau's view