 Definitions that are motivated by a skeptical attitude to supererogation often try to salvage the three-fold classification of obligation-permission-prohibition as exhausting the realm of moral actions. Some philosophers identify supererogation with imperfect duty, or with a weak duty, or with duty that is personal and non-universalizable, or with duty that has no correlative right, or with an ethical rather than legal duty, or with an “ought” which is not enforceable. Some even use the oxymoronic term “supererogatory duty” in trying to do justice to the phenomenon of supererogation without giving up the typically Kantian framing of all moral judgments in terms of duty. These are, however, mostly unsuccessful attempts. Imperfect duties, as many Kant scholars have noted, are no less compelling than perfect duties and the distinction between perfect and imperfect duty lies only in the mode of application (to what degree the conditions of its fulfillment are fixed or left to personal choice) rather than in the prescriptive force of the duty itself. And since Kant sometimes defines imperfect duties as duties to adopt ends (rather than engage in particular acts), supererogation and imperfect duty do not belong to the same level of discourse: by doing many acts of charity one does not act supererogatorily, since one cannot be more charitable than required (Guevara 1999, Baron 1987). Furthermore, if supererogation is a personal (rather than universal) duty, then is it by a subjective judgment that it is made to be so? If not, there must be some (universalizable) characteristic which lays the duty on this kind of individual. Finally, there are many duties that have no correlative rights that have nothing to do with supererogation (e.g., at least for some philosophers, duties to animals or to future people), so the test of the correlativity of duties to rights cannot account for the distinction between obligation and supererogation.