Ideology is the proper concern of all diplomatic historians. Its relevance rests on a simple proposition of fundamental importance: To move in a world of infinite complexity, individuals and societies need to reduce that world to finite terms. Only then can they pretend an understanding of their environment and have the confidence to talk about it and the courage to act on it. Policymaking, like any other individual or collective activity, requires that simplifying clarity. Policymakers get their keys to “reality” in the same ways that others in their culture do. Policymakers are formed by a socialization that begins in childhood and continues even as they try to retain those keys or to discard them as a result of experience in making decisions.

Thus, every diplomatic historian, like it or not, constantly comes in contact with the problem of ideology. Those intent on a better understanding of its importance and complexity may turn to a rich, suggestive body of literature. Part of that literature comes from political scientists preoccupied with the problem of definition. Their work catalogs the senses in which ideology is used (some twenty-seven according to one count) and sorts through the variations in meaning. Historians will find these writings particularly helpful in formulating a working definition with the greatest utility and applicability to their concerns. Those who think of the concept of ideology as unproblematic will see the importance of being explicit about what it is and what it does, while anyone inclined to downplay the role of ideas or to regard them as freestanding may well reconsider after encountering definitions with clear interpretative promise.