“Act only according to that maxim whereby you can, at the same time, will that it should become a universal law.” — Immanuel Kant What is the foundation of morality? Where do ethical duties come from—and can reason alone define what is right? In Fundamental Principles of the Metaphysic of Morals, the great philosopher Immanuel Kant lays the groundwork for one of the most influential ethical systems in Western thought. Arguing that true morality arises not from consequence, feeling, or authority, but from pure reason, Kant introduces the idea of the categorical imperative—a universal rule that binds all rational beings. In doing so, he redefines freedom, duty, and moral worth in terms that continue to shape debates in philosophy, law, and politics to this day. Accessible and thought-provoking, this modern translation captures the clarity and precision of Kant’s vision for a rational, just