Timeless Principles or Today's Fashion? Testing the Stability of the Linkage between Ideology and Foreign Policy in the Senate

The literature on the role of ideology in congressional voting argues that congressional preferences are driven by a commitment to coherent sets of ideas and principles. These ideologies imply related positions on a variety of domestic and foreign policy issues. Using data on voting in the U.S. Senate between 1947 and 1993, we present evidence that although commitment to a liberal or conservative ideology is strongly related to senators’ positions on foreign policy issues, this relationship is not stable over time. Conservatives tended to back “nationalist” policy positions prior to 1965, while liberals generally supported “internationalist” positions until 1963. After these dates, conservatives became strong supporters of internationalist positions while liberals moved toward a nationalist posture. This finding suggests that ideology should not be understood as a coherent set of ideas with consistent policy implications over time.