For more than thirty years, philosopher Bernard Gert has been developing and refining his distinctive and comprehensive moral theory. His classic work on this subject was first published in 1970 as The Moral Rules, and greatly revised editions appeared in 1975 and 1988 (the latter published by OUP under the title Morality: A New Justification of the Moral Rules). Now, in this final revision, Gert has produced his fullest and most sophisticated statement of this influential theoretical model. Morality, Its Nature and Justification differs from the previous edition in many important respects, and throughout the book, Gert attempts to answer all of the criticisms his work has attracted.