Why war? The question is asked in literature, poetry, and drama, and in innumerable studies by philosophers, historians, and political and strategic analysts. The answers have ranged from the nature of international systems to the genetic make-up of man. None is authoritative and so the question continues to be raised.

This study offers no answers, but provides some clues to understanding, clues which have not been investigated in the significantly large literature on war that has emerged in the last several decades. Instead of asking “why war?” it poses three interrelated questions: what do men fight about? how have their attitudes toward war changed? and to what extent have they succeeded in creating international orders and institutions that manage, control, or prevent international conflicts and crises from breaking out into war? We are concerned with issues, attitudes, and orders, how they are related, and how they affect the propensity of states to employ armed force in international relationships.

At least two assumptions inform the investigation. Sharing the Enlightenment's perspective on politics, I am reasonably convinced that man can build diplomatic institutions, norms, and procedures that will at least reduce the incidence of war. I do not share those pessimistic views that see war as a necessary concomitant of man's genetic make-up, a perpetual “struggle for power” among nations, or an inevitable consequence of international anarchy. Throughout the history of the nation-state system, a major opportunity for undertaking the task of doing something about war came after the conclusion of world war or major regional wars.