Abstract

Kant and Sidgwick agree that genuine ethical principles must be sourced in reason rather than divine commands. Yet, despite sharing this secular starting point, both philosophers ultimately conclude that the assumption of God’s existence is necessary for the complete viability of practical reason (including principles of morality) within human beings. This mutual reintroduction of God is especially surprising given that Kant and Sidgwick advocate divergent moral theories. The central claim of this chapter is that, despite their philosophical differences, Kant’s and Sidgwick’s respective appeals to the moral necessity of God have a common cause. Both philosophers perceive a deep human need to believe in cosmic justice (i.e., universal harmony between duty and happiness), and their shared hedonic account of well-being colors their conception of what such justice must involve. After explaining how these ideas give rise to the ostensible moral need for faith, I provide a brief defense of an alternative view based on the Stoic belief that the universe is ultimately just, despite the lack of a reliable connection between moral virtue and hedonic well-being.