 Most ethical theories maintain some form of this two-tier structure of the moral system, although admittedly in different versions and emphases. But this double role of normative discourse inevitably raises the idea of supererogation, the category of actions that are praiseworthy (either in creating good states of affairs or in reflecting a particularly virtuous trait of character) yet at the same time not obligatory. Supererogation lies at the intersection of the axiological and the deontic, the ‘good’ and the ‘ought’. Since moral theories of the past (like Aristotle, Kant and utilitarianism) all appeal in some form to both deontic and axiological concepts, the scant and cursory discussion of supererogation in those theories is all the more surprising.