Moral disagreement is not merely a familiar fact of life. For all their efforts, moral philosophers have not succeeded in showing how persistent disagreement can be overcome by monological means-even in principle. The obvious question is why moral dissonance is so prevalent: why it is that disagreement about moral matters, unlike the debates of scientists about the empirical world, are so seldom resolved. However, there is another equally important question which must also be answered. Why is it that we think that moral dissonance should be resolved or transcended? Why are we not content to believe that there is no truth of the matter as far as ethical beliefs are concerned? Why instead do we insist on trying to comprehend and argue against the positions of those who have different views? An adequate account of the nature of moral judgment must explain, or explain away, both our disagreements and our belief that we ought to be able to agree.