Moral Twin Earth Strikes Back: Against a Neo-Aristotelian Hope

Abstract A key objection to naturalistic versions of moral realism is that the (meta)semantics to which they are committed yields incorrect semantic verdicts about so-called Moral Twin Earth cases. Recently, it has been proposed that the Moral Twin Earth challenge can be answered by adopting a neo-Aristotelian semantics for moral expressions. In this paper, I argue that this proposal fails. First, however attractive the central claims of neo-Aristotelianism are, they do not for us have the status of analytic constraints on the use of ethical expressions, as they must if they are to block Moral Twin Earth counterexamples. Second, even when the neo-Aristotelian’s claims are taken as non-negotiable analytic constraints, the semantics faces a dilemma: if characteristic human functioning is understood in an ethically neutral way, the semantics yields an incorrect intension for ‘good human.’ If human functioning is understood in an ethically partisan way, the semantics fails to avoid problematic Moral Twin Earth counterexamples.