The Foundations of the Metaphysics of Morals or Groundwork of the Metaphysics of Morals (Grundlegung zur Metaphysik der Sitten), Immanuel Kant's 1st contribution to moral philosophy, argues for an a priori basis for morality. Where the Critique of Pure Reason laid out his metaphysical & epistemological ideas, this relatively short, primarily metaethical, work was intended to outline & define the concepts & arguments shaping his future work The Metaphysics of Morals. However, the latter work is much less read than the Groundwork. The Groundwork is notable for its explanation of the categorical imperative, which is the central concept of his moral philosophy.
The Groundwork is broken into a preface, followed by three sections. Kant's argument works from common reason up to the supreme unconditional law, in order to identify its existence. He then works backwards from there to prove the relevance & weight of the moral law. The 3rd & final section of the book is famously obscure. It's partly because of this he decided to publish the Critique of Practical Reason in 1788.
تأسيس ميتافيزيقا الأخلاق - أمانويل كانت