This chapter finds that Augustine self-consciously departed from Stoicism and Platonism (while remaining within eudaimonism) in finding that there were other natural objects of human beings’ eros-love besides the highest good. This finding leads to a new explanation of Augustine’s distinction between use and enjoyment and to a new explanation of his view that grief would be found not only in the lives of the vicious but in the lives of the virtuous as well.

This chapter asks whether Augustine criticised Stoicism and Platonism because he thought that there was something fundamentally flawed about the eudaimonist approach to ethics, or whether he criticised Stoicism and Platonism because he thought that these philosophies had insufficiently understood eudaimonism itself. It finds that the latter explanation is correct: in reaching this conclusion, this chapter establishes that Augustine defined virtue and vice, or sin, from within the eudaimonist tradition, making use of the ideas of love as eros and philia, and of the highest good, or summum bonum.

Famously, in the Canon of Pure Reason, Kant present a practical argument to the effect that our beliefs in God and immortality are justified. I argue that reading the Critique of Pure Reason as the doctrine of method of metaphysics provides a straightforward explanation of the systematic place of Kant’s practical argument in the Canon. Customarily, the relevance of the Critique for the practical part of metaphysics is restricted to proving the theoretical undecidability of God and immortality, but the Canon clearly goes beyond establishing that. According to its positive task as the doctrine of method of metaphysics, the Critique must establish that metaphysics can achieve ‘architectonic unity’. I argue that showing that this unity is possible for metaphysics requires showing that there is conceptual space for coherently accommodating our commitment towards the existence of God and immortality within it.

The 1786 review of Kant's Groundwork for the Metaphysics of Morals by Hermann Andreas Pistorius raised the objection that Kant's categorical imperative is an "empty formalism" that needs an antecedent conception of the good long before Hegel made the same charge in 1802.  Kant's explicit response to Pistorius in the Critique of Practical Reason is just to double-down on the priority of the right over the good.  However, I suggest that Kant's characterization of humanity as an end in itself as the "ground of a possible categorical imperative" in the Groundwork, on the one hand, and his account of the highest good as the complete object of morality in the second Critique, on the other, together provide a much fuller and satisfactory response to the "empty formalism" objection.

Kant’s moral argument for faith in God aims not at converting unbelievers but at offering those who believe a reason for principled assent to the existence of God on moral grounds. It is based on a rational connection between purposive action and assent that applies not only to religious belief but to many other purposes as well, such as what Royce called “loyalty to a lost cause.” The argument in the Critique of Pure Reason differs significantly from its presentation in later works. Kantian moral faith is in tension with Cliffordian evidentialism but not inconsistent with it, and the two together constitute the doxastic virtue lying between the twin vices of uncritical credulity and stubborn incredulity; together they enable us to avoid the complacencies of both despairing resignation and overconfidence.

Kant holds that the origin of our propensity to evil arises in connection with our unsociable sociability. The effective response to it, therefore, must also be social. We must leave the ethical state of nature and join with others in voluntary ethical community, where our shared ends, conceived as the highest good, under the legislation of a divine lawgiver will promote moral progress among human beings. The existing communities of this kind are churches and ecclesiastical faiths, which fall short of their religious vocation but can and should be reformed so as to live up to it. The relation of rational religion to revealed religion is therefore intended by Kant to be dynamic, with the interpretation of revealed religion enriching rational religion and the reform of revealed religion bringing rational and revealed religion into closer harmony, leading gradually toward the founding of the Kingdom of God on earth.