An influential argument in bioethics involves appeal to disgust, calling on us to take it seriously as a moral guide (e.g. Kass, Miller, Kahan). Some argue, for example, that genetic enhancement, especially via human reproductive cloning, is repellant or grotesque. While objectors have argued that repugnance is morally irrelevant (e.g. Nussbaum, Kelly), I argue that the problem is more fundamental: it is psychologically irrelevant. Examining recent empirical data suggests that disgust’s influence on moral judgment may be like fatigue: an exogenous (...) influence, yielding a “performance error” that does not reflect our understanding of moral matters. This conclusion also challenges appeals to repugnance on other topics (such as homosexuality) and generally downplays the importance of disgust in moral discourse. (shrink)