American political culture determines how individual policymakers regard the place and authority of international law in U.S. foreign policy. Political culture, which embraces fundamental attitudes and practices of American society, draws from two main sources. One is historical experience. Americans are products of their past. The second is the national belief system, that is, the ideas and ideologies held by the American people. The relevance and status of international law in the making of U.S. foreign policy derive from the American people's self-image, their norms and values, and the ways in which American political culture influences their perceptions of international relations. This national outlook, which might be called the American ideology, inculcates an American style in world affairs and helps to explain why and how international legal rules are integrated into U.S. foreign policy actions.
Understanding the sets of beliefs that comprise the American ideology is critical for appreciating why, where, and how much legal considerations figure into the process and patterns of American foreign policymaking. This national ideology emanates from four sets of core American self-perceptions and values, namely, the predispositions toward exceptionalism, legalism, liberalism, and pragmatism. When evaluating how these elements of American political culture affect policymakers, one must remember that each element influences personal attitudes, though in various ways and to differing degrees. A person's attitudes toward some international event can invite struggle over the priority between these elements and engender conflicted feelings over which policy appears most appropriate for U.S. interests. Similarly, a person's strength of convictions toward these elements can change over time, relative to perceptions, circumstances, and particular events.