Many scholars who have thought hard about the problems of peace and war in the thermonuclear age have concluded that mankind is faced with an unprecedented situation. Thus Kenneth Boulding (Conflict and Defense, p. 336) has remarked that “Our hope for the future of mankind… lies first in the human imagination, which can create the forms of things unknown and so create the image of possible futures that have not been previously imagined.” Thermonuclear war and world disarmament are both thought to be unprecedented possibilities. And from this belief has sprung the notion of many war-peace researchers that study of the past is unlikely to contribute much to understanding of an unprecedented future. Perhaps partly for this reason, few professional historians have become involved in the kind of peace research that has interested many economists, political scientists, and—perhaps preeminently—psychologists.