How Party Polarization Drives Affective Polarization of Voters in Multiparty Systems

Affective polarization, the degree of dislike between voters of different parties, is strongly related to the ideological distance between parties. While partisan and ideological distances are synonymous in two-party systems with a single dimension of political conflict, multiparty systems can reflect multiple dimensions of difference. To elicit which dimension is most relevant for affective polarization, we test how party polarization on the cultural and economic dimension drives the affective polarization of voters in the German states. We exploit the fact that the 16 German states provide for a lab-like environment, as they exhibit different levels of affective polarization while being nested inside the same broader party system. We present a novel data set of over one hundred harmonized surveys, containing like-dislike scores from around a quarter million respondents for each of the six major parties (CDU/CSU, SPD, FDP, Greens, PDS/The Left, AfD) at German state elections from 1990-2020. Party polarization on different dimensions is measured by the wordscores analysis of state party manifestos from 1990-2020. Using panel regression, we show that growing ideological differences on the cultural dimension between parties lead to higher affective polarization on the voter level, but not on the economic dimension. Most of this change, both in terms of affective and cultural party polarization, is driven by the AfD entering the political arena. This is in line with findings regarding the surging salience of migration issues.