This book offers the fullest and most sophisticated account of Gert's influential moral theory, a model first articulated in the classic work The Moral Rules: A New Rational Foundation for Morality, published in 1970. In this final revision, Gert makes clear that the moral rules are only one part of an informal system that does not provide unique answers to every moral question but does always provide a range of morally acceptable options. A new chapter on reasons includes an account of what makes one reason better than another and a second new chapter is devoted to the question of justifying violations of the rules. Moral impartiality, the moral ideals, and virtue and vice, are all treated in greater detail. Throughout, Gert attempts to answer all of the challenges that his work has provoked.