Personality Effects on American Foreign Policy, 1898–1968: A Test of Interpersonal Generalization Theory

Whether personality characteristics of American leaders crucially determine major American foreign policy decisions has been a matter of considerable disagreement. A test of two hypotheses drawn from interpersonal generalization theory shows such influences have probably been crucial in a number of cases in American foreign policy between 1898 and 1968. In 49 cases of intraelite disagreement on force-related issues and 13 cases of intraelite disagreement on inclusionary issues the direction of disagreement could be predicted in over 75 percent of the cases by knowledge of individual differences in interpersonal relations. A four-fold speculative typology suggests fundamental personality-based differences in orientation towards America's preferred operating style and role in the international system (e.g., introverts are drawn toward impersonal principles and mechanisms like balance of power–or in an earlier period to international law). The evidence implies that one source of war and hard-line foreign policy is the structure of self-selection and recruitment to high office in the American political system. As well, the systematic tendency to self-expressive personalization in major foreign policy decisions probably increases the rate of error of American elites.