Freedom and practical reason › Immortality and God

Kant connects immortality with an endless progress toward complete conformity of the will with moral law. He connects God with the possibility of a relation between nature, happiness, and moral worth that finite agents cannot secure by themselves. These are arguments within his account of the highest good.

Neither postulate is presented as a successful speculative proof. Theoretical reason does not thereby gain knowledge of a supersensible being's properties as it gains knowledge of objects in experience. The practical use of the ideas remains tied to the moral argument that calls for them.

The details can be contested. A reader may ask why endless progress requires the continued existence Kant postulates, or why the highest good requires a morally governing cause of nature. Those objections should address the actual steps. They do not show that Kant derives the moral law from divine commands, since the order of his argument runs in the other direction.

Freedom also appears in Kant's account of practical postulates, but its warrant has a distinctive position. The law already establishes its practical reality. God and immortality enter through further reasoning about the highest good. A simple list of three postulates is therefore useful only if these differences are kept visible.