Systemic Polarization and the Occurrence and Duration of War

The literature concerned with the relationship between polarity and war generally focuses on decision maker responses to uncertainty. That literature assumes, implicitly, that foreign-policy decision makers are generally risk-acceptant or risk-avoidant under uncertainty. I suggest several alternative formulations, based on the assumptions that (a) uncertainty is promoted by change in the structure of the international system, rather than by the actual structure itself; and (b) risk-taking orientations are normally distributed among decision makers. Using data on the occurrence and duration of war during the past century and a half, and defining polarity as consisting of three attributes—the number of poles, and their tightness and discreteness—I find no support for the hypotheses found in the literature. Considerable support, however, emerges for the hypotheses derived from the assumptions proposed here. Most significantly, the occurrence and duration of wars during the twentieth century are found to be closely linked to increases in systemic tightness.