Assumptions of Rationality and Non-Rationality in Models of the International System

It is a truism that all action within the international system can be reduced to the action of individuals. It is also true, however, that international relations cannot be adequately understood in terms of individual attitudes and behaviors. Models of the international system usually deal with larger units, nation-states, as prime actors. To what extent can such models give us adequate explanations of international relations without some built-in variables to deal with individual decision-making?It may be that some processes in international relations can be adequately explained on the level of social structure without explicit consideration of the personality, predispositions, attitudes, and behavior of the individual decision-maker. In that case, the introduction of variables dealing with individual behavior would complicate the model without commensurate payoff in terms of increased understanding and prediction. This would be true if the impact of individual decision-making on the behavior of nations in their relations with other nations were slight, or if the impact varied randomly (because, for instance, of idiosyncratic factors) among the population of international events that one was trying to explain. If, on the other hand, models of the international system that either ignore or make grossly simplifying assumptions about individual decision-making can explain international relations only very imperfectly, it may well be worth the additional effort to build variables about individual decision-making into them.