Christopher Kam, Alexander Held and I have published a paper that reveals an essential role for the bipolarity of the party system in electoral accountability. The paper is forthcoming in the American Political Science Review and its abstract appears below. For now, it is accessible via SSRN. I will update this post when the version of record becomes available.
Electoral accountability requires that voters have the ability to constrain the incumbent government’s policy-making power. We express the necessary conditions for this claim as an accountability identity in which the electoral system and the party system interact to shape the accountability of parliamentary governments. Data from 400 parliamentary elections between 1948-2012, show that electoral accountability is contingent on the party system’s bipolarity, i.e., with parties arrayed in two distinct blocs. Proportional electoral systems achieve account- ability as well as majoritarian ones when bipolarity is strong, but not when it is weak. This is because bipolarity decreases the number of connected coalitions that incumbent parties can join to preserve their policy-making power. Our results underscore the limitations that party systems place on electoral reform and the benefits that bipolarity offers for clarifying voters’ choices and intensifying electoral competition.