The Sage of Königsberg

Better than anyone, Kant recognized the power and authority of the moral law. On that foundation he constructed two variants of the moral argument. His argument from grace pertains to whether or not the moral life is possible. Morality requires us to achieve a stand too demanding to meet on our own. Divine assistance is needed to close the resulting gap. So rationality dictates that we postulate God’s existence. Kant’s argument from providence pertains to the aforementioned rational need for happiness and virtue to cohere. Full rational commitment to morality requires that morality is a rationally stable enterprise, which entails the ultimate correspondence between virtue and (both individual and corporate) fulfillment. Without God’s existence there’s no particularly good reason to think such correspondence obtains. So rationality dictates the postulation of God’s existence.