Published online by Cambridge University Press: 18 May 2020
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 and 2012 show that electoral accountability is contingent on the party system’s bipolarity, for example, with parties arrayed in two distinct blocs. Proportional electoral systems achieve accountability 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.
We thank participants at the Southern California Comparative Political Institutions meetings, participants at seminars at the London School of Economics, King’s College London, the University of Essex, University of California-San Diego, University of Lausanne, and the University of Mannheim, and Jose Antonio Cheibub, Shaun Bowler, Lucy Barnes, and G. Bingham Powell Jr. for their helpful comments. Replication data and code and the appendix can be found at: https://doi.org/10.7910/DVN/5QBS9A