Supererogation seems to be an important concept of common sense morality. However, assuming the existence of such a category seems to pose a serious problem for Kantian Ethics, given the all-encompassing role of duty. In fact, Kant seems to deny the possibility of such acts when he states in the second critique that “[b]y exhortation to actions as noble, sublime, and magnanimous, minds are attuned to nothing but moral enthusiasm and exaggerated self-conceit; [...] they are led into the delusion that (...) it is not duty […] which constitutes the determining ground of their actions […]”. (KpV, AA V, 84f.). This paper’s aim is to show that even though it is not possible to include a category of supererogation within Kantian Ethics, the recognition of alleged supererogatory acts is not only a source of self-deception, as Kant seems to fear, but can also serve as a source of self-knowledge. Starting from the premise that within Kantian Ethics self-knowledge is indispensable to aspire to the duties of moral self-perfection, I will argue that supererogation is only a plausible concept regarding the observer-perspective: thus it describes an act that, given the observer's own moral development, seems to be beyond duty but for the agent herself is not. Given an observer has the insight that her judgment relies on her own deficiencies to act accordingly, this fulfills an epistemic function in the process of developing one’s own moral capacities. This seems to be a fairly proper phenomenological account of supererogation as it can, on the one hand, explain the common moral intuition that certain acts are supererogatory. While on the other hand, it can capture the empirical observation that agents of alleged supererogatory acts usually do not perceive their actions as supererogatory because the differing perspectives of the agent and the observer constitute an integral part of the given account. (shrink)