The natural law tradition, which takes as central to moral discussion an appeal to our common humanity, provides a sustainable and attractive approach to problems of ethics and morals. This volume presents a contemporary version of natural law ethics, one that does not rely for support on the authority of Aristotle or St. Thomas Aquinas, however much it is indebted to them and their followers for inspiration and arguments. The author discusses the mutual relations of four key moral concepts—the good, virtue, duty, and rights—as well as their application to various issues, including environmental concerns, homosexuality, and suicide. While examining the role of morality in a way of life and the relation between morality and religion, he defends the natural law tradition against a range of philosophical and theological opponents.