On the Validity of A Simple Argument for Moral Error Theory

In The Myth of Morality Richard Joyce presents a simple and very influential argument for the truth of moral error theory. In this paper I point out that (i) the argument does not have the form Joyce attributes to it, (ii) the argument is not valid in an extensional propositional logic and (iii) on the most natural way of explicating the meanings of the involved terms, it remains invalid. I conclude that more explanation is needed if we are to accept this particular argument for moral error theory.