potential impacts of partisan/ideological polarization
Elite polarization refers to polarization in the party-in-government and party-as-organization. It occurs when party members (both elected government officials and activists within the party organization itself) grow more internally homogenous on policy positions and more divergent relative to members of other parties. Polarized political parties are internally cohesive, unified, programmatic, and ideologically distinct; they are typically found in a parliamentary system of democratic governance.
In a two-party system like the U.S., a polarized legislature has two important characteristics: first, there is little-to-no ideological overlap between members of the two parties; and second, almost all conflict over legislation and policies is split across the broad liberal/conservative ideological divide. This leads to the conflation of political parties and ideologies (i.e., Democrat and Republican become nearly perfect synonyms for liberal and conservative) and the collapse of the ideological center.
The vast majority of studies on elite polarization focus on legislative and deliberative bodies. For many years, political scientists measured polarization by examining the ratings of party members published by interest groups, but now, most analyze roll-call voting patterns to determine trends in party-line voting and party unity. Many political scientists studying American politics rely on Poole and Rosenthal’s DW-NOMINATE scores, which assign a single liberal-conservative score to each congressperson, enabling comparisons of members from different Congresses. There is much more research on polarization in Congress than on polarization in the other branches of government or in state governments. Azzimonti’s political polarization index is more comprehensive instead because it is based on media coverage of newspaper articles reporting political disagreement about policy in all branches of government. Recent work by Gentzkow, Shapiro, and Taddy has used the text of the Congressional Record to document differences in speech patterns between Republicans and Democrats as a measure of polarization. They find that polarization has increased dramatically since 1994.[15