Polarized preferences versus polarizing policies

Much of contemporary political debate in the United States focuses on the issue of polarization: specifically, its causal antecedents and its consequences for policymaking and political conflict. In this article, we argue that partisan preference polarization—conventionally defined as the difference in the favored policy positions of legislators from the two major parties—is not a sufficient statistic for potential political conflict in national politics. Rather, a well-defined measure of potential conflict must take into account (1) the locations of status quo policies and proposed alternatives; and (2) the shape of underlying utility functions. We propose measures of the likely contentiousness of a given status quo policy and of a proposal to move that policy. We then demonstrate the usefulness of these measures using estimates of utility function and final passage vote parameters on enacted legislation from the 111th US Senate (2009–2011).