Han, S. M. (2015) “Income inequality, electoral systems and party polarisation”, European Journal of Political Research 54 (3), 58
Previous work on party polarisation often
considered income inequality as the main cause of polarisation. However, while empirically in some countries income inequality and party polarisation are strongly related, in other countries a
close correlation is not observable.
The article by Han contributes to this field of research by arguing that the electoral system acts as an intervening variable either facilitating or hindering parties to take more divergent positions on redistributive policies when income inequality rises. Based on data that covers 24 advanced democracies over a period of time from 1960 to 2011, the study finds that under permissive electoral systems increasing income inequality leads to a rise of party polarisation. Furthermore, the analysis provides evidence that there is no positive effect of rising income inequality on party polarisation in restrictive electoral systems. This difference between electoral system types is due to the unsureness of parties in restrictive electoral systems whether taking more extreme positions will result in more votes. Gaining the support of the median voter is more crucial in restrictive systems compared to permissive systems. Interestingly, the study finds no strong statistical relation between party polarisation and the factors of income inequality and the electoral system themselves without their interaction.
Additionally, Han presents an interesting argument for why a general effect of increasing income inequality on party polarisation does not exist, showing that the role of electoral systems and, ensuing, strategic concerns of political parties need to be taken into account. The time-series cross-sectional model is well-specified, including a broad set of control variables. Additionally, the author provides several robustness checks, also comparing different measures of the dependent variable. While the study clearly indicates that when income inequality increases, under permissive electoral systems, parties overall tend to take more extreme positions to target their core supporters, i.e. the “poor” (left parties) and the “rich” (right parties). This raises the question of possible differences in that effect on parties’ ideological positioning (and their causes) for left as well as right parties between different countries. Hence, this is a phenomenon that awaits further investigation.