What is morally permissible and what is morally obligatory? These questions form the core of a vast amount of philosophical reasoning. In his Fundamental Principles of the Metaphysic of Morals Immanuel Kant developed a basis for the answers.Kant's test known as the Categorical Imperative is a logical proof of the Golden Rule and the centerpiece of this work. It constitutes his best-known contribution to ethical discussion and a familiarity with his reasoning in this book is essential to students of philosophy religion and history.