Abstract: The ancient Greeks subscribed to the thesis of the Unity of Virtue, according to which the possession of one virtue is closely related to the possession of all the others. Yet empirical observation seems to contradict this thesis at every turn. What could the Greeks have been thinking of? The paper offers an interpretation and a tentative defence of a qualified version of the thesis. It argues that, as the Greeks recognized, virtue essentially involves knowledge – specifically, evaluative knowledge of what matters. Furthermore, such knowledge is essentially holistic. Perfect and complete possession of one virtue thus requires the knowledge that is needed for the possession of every other virtue. The enterprise of trying to reconcile the normative view embodied in this conception of virtue with empirical observation also serves as a case study for the field of moral psychology in which empirical and normative claims are often deeply and confusingly intertwined.
Comment: Useful as further reading in courses focusing on ancient and moral philosophy. Can be particularly useful in teaching on topics related to moral psychology and its relations with moral philosophy.