The Quantity and the Quality of Party Systems

TLDR

Prior studies link the number of parties to representation of social cleavages, voter turnout, conflict patterns, and other party‑system effects. The article argues that research overemphasizes party quantity while the quality of party competition—specifically polarization—is the more consequential factor to study. A new polarization metric based on voter perceptions from the Comparative Study of Electoral Systems is introduced and compared with fractionalization to evaluate their influence on cleavage‑based and ideological voting and turnout. The results show that party polarization better explains voting behavior and turnout than party fractionalization.

Abstract

Previous research claims that the number of parties affects the representation of social cleavages in voting behavior, election turnout, patterns of political conflict, and other party system effects. This article argues that research typically counts the quantity of parties and that often the more important property is the quality of party competition—the polarization of political parties within a party system. The author first discusses why polarization is important to study. Second, the author provides a new measurement of party system polarization based on voter perceptions of party positions in the Comparative Study of Electoral Systems, which includes more than 50 separate elections from established and developing democracies. Third, the author compares party polarization and party fractionalization as influences on cleavage-based and ideological voting and as predictors of turnout levels. The finding is that party polarization is empirically more important in explaining these outcomes.