Power, vulnerability, and Zinnes's interaction puzzle

Zinnes's interaction puzzle asks why data‐based studies of arms races and crisis interaction discover little or no responsiveness among contending states. The difficulty of mapping threats to responses in a bilateral conflict can block analysts’ efforts to investigate the nature of these interactions. Moreover, analyses of foreign policy decisionmaking have difficulty incorporating power as a formal variable, and systemic analyses of power often abstract interaction processes from the discrete options available to policymakers. Theoretical research that takes these difficulties seriously can benefit from analytical techniques that integrate the substi‐tutable options available to policymakers with the traditional concept of power ratios. The analytical framework developed in this paper suggests that the two types of analysis can be integrated parsimoniously. It highlights the concepts of power and vulnerability in a system of states where the options foreign policymakers pursue importantly affect these two critical variables. Further, its equations improve methods of calculating power ratios in dyadic interaction and contribute to systematic thinking about foreign policy substitution effects.