Polarity and stability: New concepts, indicators and evidence

One of the most sustained debates among students of international politics concerns the linkage of systemic polarity to levels of stability. The present investigation attempts to contribute to this dialogue in two ways. First, prior studies of polarity and stability are reappraised in terms of the central concepts and presumed causal linkage, leading to several changes in approach. Specifically, polarity cannot be assessed only in terms of the distribution of power; the concept also should incorporate the notion of autonomous decision centers. With respect to instability, war is considered to be a less complete indicator than international crisis. Incorporating these revised concepts, a model of security regimes is devised deductively, including a rank‐ordering of polarity configurations in terms of stability levels. Second, renewed testing focuses on the presumed ordering of configurations from most to least stable: bipolarity (1945–62), multipolarity (1929–39) and polycentrism (1963–85). Data from the International Crisis Behavior Project on 292 cases from 1929 to 1985 provide the evidence to compare the phases of polarity. A set of bivariate indicators and a multivariate index are used in the assessment of instability, with each confirming the hypothesized ordering of polarity configurations.