Freedom and practical reason › The highest good

Kant's highest good brings virtue and happiness into a specific relation. Virtue has priority: it concerns worthiness to be happy. A complete good for finite rational beings also includes happiness in proportion to moral worth. Happiness is not treated as a reason for buying moral compliance.

The order matters. If I first asked which moral behavior would earn the largest reward, I would make an expected benefit the determining ground of my will. Kant's argument instead begins with the moral law and then asks about the complete object of a will governed by it.

The highest good therefore belongs to a later stage of the argument. It does not replace the law with an instruction to maximize pleasant experiences. Nor does it establish that virtuous people will receive fair treatment in the ordinary course of events. The mismatch between moral worth and happiness is part of what makes the later discussion necessary.

Imagine a just person suffering while an unjust person prospers. Kant does not infer that justice ceases to bind. He asks how the pursuit of a world in which moral worth and happiness correspond can be a rational object of practical reason. Understanding that question is necessary before assessing the postulates that follow.