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.

Conventional theories of elections hold that an election is analogous to a consumer product market. According to the market paradigm, voters are consumers, candidates are competing firms, and an election is a market in which voters exchange votes for policy by voting for the candidates whose policies they prefer. According to this logic, a healthy democracy requires frequent competitive elections. The market analogy underlies decades of electoral theory, but in Hiring and Firing Public Officials, Justin Buchler contends that it does not capture the real nature of elections. In fact, our widespread dissatisfaction with the current state of electoral politics derives from a fundamental misunderstanding of what elections are and what purpose they serve. As Justin Buchler shows, an election is a mechanism by which voters hire and fire public officials. It is not a consumer product market--it is a single employment decision. Thus, the health of democracy depends not on regular competitive elections, but on posing a credible threat to fire public officials who do not perform their jobs well. However, the purpose of that threat is to force public officials to act as faithful public servants so that they do not have to be fired. Thus, competitive elections, by most definitions, are indicative of a failure of the democratic system.

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.