The Part III unfolds a theory of supererogation within the framework of a Plea for a Strong Rationalist Supererogationism with a Virtue-Ethical Outlook (see Sect. 7.5) in order to defend the Argument of Supererogation and to resolve its Indecency Problem (see Sect. 2.3.4). The second premise P2 of the Argument of Supererogation states that the actions which are to be denied with the argument are morally valuable actions. Regarding this second premise, there is a broad consensus in supererogation research, as there would be no debate about the Paradox of Supererogation or about whether an action is to consider a duty if it is not morally valuable (see Part II). In the Argument of Supererogation, the premise is also indispensable because there would be no reason to bring the argument into play if the debated actions are not morally valuable. Chapter 8 unfolds the three conditions of the moral value of an action: an action is morally valuable if it promotes and preserves the legitimate interests of moral actors (effect), if it is intended that it promotes and preserves these interests (intention), and if it is based on a morally good motive (motive). These three conditions are defended as necessary conditions.