Despite much discussion over the existence of moral facts, metaethicists have largely ignored the related question of their possibility. This paper addresses the issue from the moral error theorist’s perspective, and shows how the arguments that error theorists have produced against the existence of moral facts at this world, if sound, also show that moral facts are impossible, at least at worlds non-morally identical to our own and, on some versions of the error theory, at any world. So error theorists’ arguments warrant a stronger conclusion than has previously been noticed. This may appear to make them vulnerable to counterarguments that take the possibility of moral facts as a premise. However, I show that any such arguments would be question-begging.
Moral error theory Moral realism Possible worlds Moral supervenience