Edgar learns from his teachers that, if lying is wrong, liars will be punished in the afterlife. Through philosophical reflection, Edgar later comes to accept that lying is wrong. He infers that liars will be punished in the afterlife. Cian Dorr observes that Edgar's inference could well be epistemically rational, for he seems to be justified in accepting its premises. But according to moral non-cognitivism, to come to accept that lying is wrong is merely to acquire a new desire-like attitude. A mere change in Edgar's motivational states could not make it rational for him to change his beliefs about the nature of the afterlife. That would be akin to wishful thinking. So if non-cognitivism is true, Edgar's inference could not be rational. Since Edgar's inference clearly could be rational, Dorr concludes that non-cognitivism is false.

I defend non-cognitivism by showing that we have intuitive grounds to doubt the initial appearance that Edgar's inference could be rational.