This book is a selective historical and critical study of moral philosophy in the Socratic tradition, with special attention to Aristotelian naturalism. It discusses the main topics of moral philosophy as they have developed historically, including: the human good, human nature, justice, friendship, and morality; the methods of moral inquiry; the virtues and their connexions; will, freedom, and responsibility; reason and emotion; relativism, subjectivism, and realism; the theological aspect of morality. The first volume discusses ancient and mediaeval moral philosophy. The second volume examines early modern moral philosophy from the 16th to the 18th century. This third volume continues the story up to Rawls's Theory of Justice.