The Critique of Practical Reason

Following his analysis of pure reason, Kant turns his attention to the moral agency of the human will. He argues that while we cannot know freedom or God through scientific reason, we must postulate them as necessary conditions for the moral law to exist. The text establishes the priority of practical reason in guiding human conduct towards the highest good. It is a cornerstone of modern ethical philosophy, asserting the absolute value of the moral law within.