Electoral reforms and the transformation of party system : Thailand in comparative perspective

Most studies of electoral system effects tend to ignore the characteristics of parties in the causal chain. Yet, this dissertation argues that different party structures, when interacting with electoral systems, lead to different levels of party system fragmentation. In a weak party structure, elite action is the key to explaining the different outcomes: a permissive electoral system tends to inflate the number of parties because the rule poses an obstacle to elites’ electoral coordination. But this major obstacle is removed under a restrictive rule, which results in lower fragmentation. By contrast, the role of voters becomes active in a strong party structure; therefore, the effects of permissive and restrictive electoral systems become similar as both tend to bring down the number of parties through voters’ strategic behavior. This dissertation tests the theory on Thailand since the country has gone through three waves of electoral reform in which the electoral system has been changed between a permissive and a restrictive electoral rule. At the same time, the party structure has changed following the victory of the Thai Rak Thai Party in the 2001 election. The changing interactions of party structures and electoral systems provide a quasiexperimental setting conducive to inspecting the effects of the key factors on party system fragmentation while other confounding variables (social heterogeneity and viii political institutions) are held constant. This research design allows me to compare periods of time in different configurations of party system fragmentation. This dissertation applied multi-methods, including case study analysis, single-country multilevel quantitative analysis, and a large N, cross-national quantitative analysis, to reach the conclusions. Theoretically, the findings suggest that electoral system effects are contingent on party structures. Successful institutional engineering requires deep understanding of both formal rules and the political context of a particular country. In other words, one size cannot fit all, even for the same country at different times.