Incremental Polarization

As the last decade has shown, ideological polarization in Congress has reached historic levels. Yet, spatial theory has become increasingly important for how scholars understand Congress and legislative elections. In spatial models, candidates select positions along an ideological spectrum, and voters choose candidates based on those locations. However, the central tendency of these models is for the candidates to converge to the location of the median voter, so polarization has become increasingly problematic for spatial theory, even as scholars have come to rely increasingly on these models. In Incremental Polarization, Justin Buchler provides a unified spatial model of legislative elections, parties, and roll call voting to explain the development of polarization in Congress. His model moves beyond elections and factors in legislators' roll call voting, where a different but related spatial process operates. By linking these models, Incremental Polarization fills a critical gap in our understanding of the strategic, electoral, and procedural roots of polarization-and the role that parties play in the process.

Justin Buchler is Associate Professor of Political Science, Case Western Reserve University and author of Hiring and Firing Public Officials (Oxford University Press).

Chapter 1: Introduction Chapter 2: Voter Preferences Over Bundles of Roll Call Votes Chapter 3: The costs of incremental positioning Chapter 4: A unified spatial model of Congress Chapter 5: Polarization and solving the collective action problem Chapter 6: The collective action problem in practice Chapter 7: Extreme reversion points and party leadership from 2011 through 2016 Chapter 8: Conclusions Appendix A: Incremental positioning and multidimensional policy spaces Appendix B: Ideologically unsophisticated voters and bundles of roll call votes References