Does Moral Disagreement Pose a Semantic Challenge to Moral Realism?

Many philosophers have argued that moral disagreement raises metaphysical and/or epistemological challenges for moral realism. In this paper, I consider whether widespread moral disagreement raises a different sort of challenge by threatening the semantic commitments of moral realism. In particular, I suggest that the character of many moral disagreements gives us reason to suspect that not all competent moral speakers pick out the same properties as one another when they use moral terms. If this is so, both sides of a moral dispute may speak truly, and the standard realist diagnosis of such disputes-that at most one party can be correct-is mistaken. My argumentative strategy is to first isolate some features of linguistic exchanges that provide evidence of a lack of co-reference, and then argue that many moral disputes have these features. I conclude by suggesting that there are plausible accounts of moral disputes that do not require co-reference.