Some of the recent trends in historicalwriting downplay the importance of individuals and ideas and stress instead the role of impersonal forces in history. Although that ordering of priorities has its justifications, this study will argue to the contrary of it. The fact that Dean Gooderham Acheson, rather than someone else, was secretary of state in the Truman administration mattered a great dealin the diplomatic history of that administration and in the international relations of the allied powers and their adversaries in the late 1940s and early 1950s.
Individuals make choices, and U.S. foreign policy did, in fact, change when Acheson entered and left high office. Human agency is an especially key factor in foreign policy making. Diplomacy, in the final analysis, is neither accidental nor impersonal; if it were, individuals would be absolved of responsibility for the policies they make. Although constraints on individual policy makers are often formidable, their decisions are never altogether predetermined. As two historians of American diplomacy have stated in another context, “Decisions were taken by fallible, flesh-and- blood human beings who faced real choices and who cannot be dismissed as mere chips on the tide of history.” 1.
Historians as well as socialscientists have recently given increased attention to the psychological dimensions of decision makers and decision making. Richard H. Immerman and many others have studied the impact of personality on policy. “Cognitive psychologists uniformly agree that once we have formed a belief we are reluctant to discard or even qualify it, ” Immerman has written. “New evidence will be interpreted to conform to our prior beliefs: If it is consistent with them, it will be accepted; if inconsistent or ambiguous, it will be discredited or ignored. This tendency is most pronounced when the belief is deeply felt and deeply held.” Psychological theory can thus help us explain how and why decision makers decide as they do by providing, among other things, “clues for locating____________________