An Expected Utility Theory of International Conflict

An expected utility theory of necessary, but not sufficient, conditions for the initiation and escalation of serious international conflicts, including war, is proposed. The theory leads to the seemingly obvious generalization that actors do not initiate wars—or serious disputes—if they do not expect to gain from doing so. Underlying that generalization are a number of counterintuitive deductions. For instance, I show that though a weak nonaligned state cannot rationally attack a stronger nonaligned nation, it might be able to attack a stronger adversary that, in addition to its own strength, expects to derive support from allies. I also show that serious conflict is more likely between very close allies than between enemies. Systematic tests, using data on serious international threats, military interventions, and interstate wars, as well as 17 cases of known attempts at deterrence, show very substantial support for the expected utility propositions deduced from the theory.