Moral inconsistency is an understudied phenomenon in cognitive moral psychology and deserves in depth empirical study. Moral inconsistency, as understood here, is not formal inconsistency but inconsistency in moral emotion and belief in response to particular cases. It occurs when persons treat cases as morally different that are really morally the same, even from their moral perspective. Learning to recognize and avoid such moral inconsistency in non-trivial but is a form of moral learning that complements and enhances other psychological and social mechanisms through which persons learn how to apply shared moral norms when their applications are uncertain and threaten to lapse into moral inconsistency. The same psychological process also can function to revise current moral norms when their straightforward applications are morally inconsistent with more basic moral commitments. Through this moral learning and related kinds, people can learn how to identify issues of moral priority when moral norms conflict and, when necessary, how to revise their moral norms. The recent revolution in dominant moral norms around gay sex and gay marriage in Europe and North America provides a possible illustration. When coupled with other modes of moral learning in the context of ambiguous but deeply rooted moral norms, such as those of sanctity and authority, reflection on moral inconsistency can help to justify this large-scale moral change, even among those who find gay sex, by its nature, morally repugnant.