Reason and war

A new specification of the expected utility model of international conflict places expected utilities within a polar coordinate system; treats third-party choices in a manner more consistent with classical forms; estimates the expected utilities derived from not challenging existing policies; more fully represents the expected costs of conflict; and normalizes expected utilities regardless of system size. By assuming that the probability of escalation of a dispute increases monotonically with leaders’ expectations of gain, we derive continuous functions for the probabilities of war, intervention, violence, and peace. The revised theory significantly improves our ability to discriminate between violent and nonviolent disputes and between violent disputes that escalated to warfare and those that did not in Europe between 1816 and 1970.