  Kant holds that reason unavoidably produces not only consciousness of the moral law but also the idea of a world in which there is both complete virtue and complete happiness, which he calls the highest good. Our duty to promote the highest good, on Kant’s view, is the sum of all moral duties, and we can fulfill this duty only if we believe that the highest good is a possible state of affairs. Furthermore, we can believe that the highest good is possible only if we also believe in the immortality of the soul and the existence of God, according to Kant. On this basis, he claims that it is morally necessary to believe in the immortality of the soul and the existence of God, which he calls postulates of pure practical reason. This section briefly outlines Kant’s view of the highest good and his argument for these practical postulates in the Critique of Practical Reason and other works.