This award supports an ambitious program of research to advance understanding of the conditions likely to promote or discourage war between major international powers. A long standing assumption of international relations, but one rarely tested systematically, is that the structure of the international system significantly influences the probability of war. In particular, it is held that the probability of war increases with the level of uncertainty in the international system about the likely outcome of war. This is linked in turn to the number and relative power of nations and alliances in the international system. This research develops and tests a series of hypotheses about the probability of war which derive from a theoretical model integrating the structure of the international system with the propensity of national decision makers to take risks. Systematic tests of these hypotheses will be undertaken using data on the population of great power rivalries that have been catalogued since 1816. In addition comparative case studies of both typical and deviant cases will be undertaken to illustrate in greater detail the results of the statistical analyses and to illuminate areas of weakness. Finally, the implications of the analysis will be explored for possible lessons for reducing the likelihood of great power war in the contemporary international system. When completed this research will strengthen our theoretical understanding of the effects of different international structures or world orders on the likelihood of war and facilitate judgements about the desirability about proposed changes in international structure.
