This essay concerns the theory of the conditions under which war might end. Chapter 1 introduces the topic. Chapter 2 presents the hypotheses that a modest change in moral beliefs could catalyze the conditions needed to end war; and that a more profound change in moral beliefs, likely to follow the initial abolition, could prevent the future re-institution of war. Chapters 3–6 give theoretical and empirical evidence to support these hypotheses, and address three factors that are widely believed to preclude the abolition of war: innate aggressiveness, moral beliefs about ends that justify the use of armed force, and the tendency of political institutions, including peace-enforcement institutions, to collapse under stress.
Chapters 3–6 focus on the relative weight of learned moral beliefs and innate aggressive impulses in causing and preventing various forms of socially-sanctioned and non-sanctioned violence. These chapters present extensive evidence from various branches of psychology to show that while innate aggressive impulses can lead to non-sanctioned individual and mob violence, culturally-determined moral beliefs dominate innate aggressiveness in accounting for organized, socially-sanctioned, large-group violence. Then, surveying various forms of socially-sanctioned violence, they show that the moral beliefs which support such practices tend to change over time, leading to the permanent abolition of previously sanctioned forms of violence. The inference is drawn that in the same manner, the declining tolerance for war could lead to its abolition.
Previously morally-sanctioned and institutionalized but now abolished forms of large-group violence include ritual cannibalism, human sacrifice, slavery, and gruesome forms of corporal punishment. The case of ritual cannibalism is reviewed in depth and other cases are reviewed more briefly to assess the importance and variability of moral belief in the conduct of socially-sanctioned forms of violence, and to illuminate the historical precedents for the potential abolition of war.
The essay concludes with a discussion of the implications of the rise and demise of successive forms of socially-sanctioned large-group violence for anthropological theories of cultural evolution and state formation.