Freedom and practical reason › What practical reason does

Suppose someone threatens you with a severe punishment unless you give false evidence against an innocent person. You cannot be confident that you would resist. Yet you can distinguish the question of what you would do from the question of what you ought to do. Immanuel Kant uses a version of this situation in the Critique of Practical Reason to examine how awareness of duty is connected with awareness of freedom.

The book, published in 1788, asks whether reason can determine a will independently of the ends supplied by desire. Kant's answer connects the moral law with freedom, then develops an account of the highest good and practical faith. The connections have different roles. Freedom is the condition of moral agency; God and immortality enter a later argument about the highest good. Reading them as three interchangeable assumptions obscures the structure of the book.

Theoretical inquiry asks what is the case. Practical reasoning asks what to do. A practical question can be instrumental: given that I want to reach a town before evening, which route should I take? Answering it requires information about distances and transport, together with an end I have already adopted.

Kant asks whether this exhausts reason's practical authority. If every reason depended on a desired result, a person could apparently escape a requirement by abandoning the corresponding desire. Instructions about reaching the town no longer direct me if I decide to stay home. Moral requirements seem to claim a different kind of authority.

Consider a person who can profit from deceiving someone. An instruction to avoid deception because it may damage a reputation depends on an expected consequence. A demand to deal honestly can claim authority even when discovery is unlikely. Kant wants to explain that stronger claim without grounding it in fear of punishment or hope of reward.

The issue is not whether consequences matter to every practical decision. Choosing means to a legitimate end remains necessary. The issue concerns the basis of a moral law. Kant denies that an end supplied by inclination can establish a requirement binding every rational will as such.