Morality among Nations, a rejoinder to Hans Morgenthau's Politics among Nations, offers a pathbreaking synthesis of sociobiology and international relations theory. It shows that two different moralities evolved in human pre-history-one, the "standard morality" from which abstract ethical principles arise concerning such things as obligation and justice; and the other, "group morality" or the proclamation of the group's right to survive and its superiority over other groups.

Part One surveys the philosophical literature on the question of international morality, introducing arguments offered by both classical theorists such as Machiavelli, Hobbes, and Grotius, as well as twentieth century writers such as Reinhold Niebuhr, Hedley Bull, Richard Falk, and Charles Beitz. Part Two presents the relevant sociobiological theories focusing on Robert Trivers' work on the evolution of moral emotions, and Richard Alexander's and Pierre van den Berghe's work on the evolution of group behavior and ethnocentrism. Part Three analyzes the traditional philosophical work on international morality in light of new sociobiological ideas.