This chapter shows that early modern metaphysics was far more important for Pufendorf’s moral philosophy than has often been thought. In particular, it is essential to understanding Pufendorf’s theory of moral entities. This theory is often regarded as voluntarist and anti-metaphysical. Opposed to this, it has been argued, was a rationalist belief in objective and eternal moral values that was exemplified by philosophers like Leibniz. However, the main distinction for Pufendorf was not between voluntarism and rationalism, but between moral rules that were specific to a certain society because they were merely conventional, and others that were universal because they were natural, in the sense of being grounded in the physical characteristics of human nature as it had been created by God. The latter, according to Pufendorf, were necessarily true, though their necessity was hypothetical rather than absolute. Pufendorf’s intention was to turn moral philosophy into a science, which would supersede traditional Aristotelian-scholastic views that morality was concerned with the contingent circumstances of actions, and therefore incapable of ‘scientific’, that is syllogistic proof. Pufendorf’s theory of moral entities was central to this project of a moral science, which required him to provide a metaphysical foundation for these entities.

Chapter 10 reconstructs Durkheim's conception of sociology as a science of morality, which includes three tasks: orienting our conduct via an account of a morally healthy society; illuminating the connection between social functioning and morality (explaining why moral and social health are the same; and explaining why the moral ideals animating a given society do so and how they vary with changing social conditions. Durkheim's science of morality is similar to Marx's historical materialist account of morality, although the former leaves the moral authority of the rules it explains largely intact. While Durkheim's accounts of specific pathologies imply a critique of certain social rules, they do not discredit the fundamental norms at work in the societies he studies. The chapter concludes that Durkheim does not adequately explain how historically specific moral systems can claim a moral authority irreducible to the narrowly functional value they have for social reproduction.

Trying to find intellectual space between theology and raison d’état, the Protestant Hugo Grotius aimed to derive an autonomous sphere of legality from the natural inclination of humans to follow rules even when that might appear against their immediate self-interest. The rules he wrote into De iure belli ac pacis (On the Rights of War and Peace) combined a contractual justification of absolutism with a system of individual rights that he believed underwrote the spectacularly successful commercial practices of his native Holland. This rule-system would accommodate the actual practices of European warfare and government while also appealing to the better natures of European rulers. Unlike Gentili, Grotius viewed law as a moral science that engaged both the external behaviour as well as the conscience of those who govern.