In "Fundamental Principles of the Metaphysic of Morals," Kant explores the ethical foundation of human actions. He argues for the supremacy of moral duty based on rational principles, emphasizing the intrinsic value of goodwill. Kant's deontological ethics asserts that individuals should act according to universalizable moral maxims, independent of consequences. The text delves into the concept of categorical imperatives and the autonomy of the moral law, shaping a profound philosophical framework for ethical decision-making.