The effects of district magnitude and social diversity on party system fragmentation in majoritarian systems

Cross-national models of party system fragmentation hold that social diversity and district magnitude interact: higher levels of district magnitude allow for greater expression of social diversity that leads to higher levels of party system fragmentation. Most models, however, ignore differences between majoritarian and proportional electoral rules, which may significantly alter the impact of district magnitude, as well as the way in which district magnitude impacts the translation of social cleavages into party system fragmentation. Examining the case of Singapore suggests majoritarian multimember districts limit party system fragmentation, particularly by reducing the degree to which ethnic and religious diversity are translated into political parties. Applying these insights to a standard cross-national model of party system fragmentation, the results suggest that majoritarian multimember districts produce lower levels of party system fragmentation than proportional multimember districts.