Martha Nussbaum's work has been characterized by a sustained critique of Stoic ethics, insofar as that ethics denies the validity and importance of our valuing things that elude our control. This essay explores the idea that the very possibility of morality, understood as social or interpersonal ethics, presupposes that we do value such things. If my argument is right, Stoic ethics is unable to recognize the validity of morality (so understood) but can at most acknowledge duties to oneself. A further implication is that moral luck, so far from undermining morality as some have held, is presupposed by the very possibility of morality.