Using the most extensive collection hitherto of his published and unpublished writings, this volume provides a comprehensive, in-depth and interdisciplinary study of the ethical philosophy of al-Razi (1149-1210), a most outstanding and influential medieval philosopher-theologian.A complex picture emerges, across his philosophical, theological, ethical and juristic works, of a consistent and multi-layered ethical theory. Al-Razi departs from classical Ash'ari divine command ethics to develop both a consequentialist ethics of action, which seriously rivals Mu'tazili deontological ethics, and a perfectionist ethics of character. Within the latter framework, he sets out his later, teleological theory of prophecy.The volume includes the text, published for the first time, of one of al-Razi's latest and most fascinating works, Censure of the Pleasures of This World, which expresses pronounced moral and epistemological pessimism.