Empirical moral psychology is sometimes dismissed as normatively insignificant because it plays no decisive role in settling ethical disputes. But that conclusion, even if it is valid for normative ethics, does not extend to bioethics. First, in contrast to normative ethics, bioethics can legitimately proceed from a presupposed moral framework. Within that framework, moral psychology can be shown to play four significant roles: it can improve bioethicists’ understanding of the decision situation, the origin and legitimacy of their moral concepts, efficient options for implementing decisions, and how to change and improve some parts of their moral framework. Second, metaethical considerations suggest that moral psychology may lead to the radical revision of entire moral frameworks and thus prompt the radical revision of entire moral frameworks in bioethics. However, I show that bioethics must either relinquish these radical implications of moral psychology and accept that there are limits to progress in bioethics based on moral psychology or establish an epistemic framework that guides radical revision.