Parity, Disputed Issues, and the Evolution of Interstate Rivalry

Abstract: Recent scholarship has generated two general conceptions of the development of interstate rivalry. Goertz and Diehl’s “basic rivalry level ” (or BRL) approach postulates that adversaries “lock in ” to rivalries quickly and subsequently see little variation in conflict levels. The alternative, Hensel’s “evolutionary ” approach, argues that rivalries develop more gradually over time as two adversaries accumulate hostility and grievances from past confrontations. Some evidence has been found to support each of these conceptions, although it appears that neither approach is more useful than the other in every situation. This paper attempts to identify situations in which each approach might be most useful, focusing on the impact of rough parity in national capabilities and the types of disputed issues separating states. We develop and test hypotheses on the relationship between parity, issues, and rivalry behavior.