Voting Rules, Electoral, Effects of

Voting rules determine how voters cast their ballots and how vote shares are converted to seats or mandates in the elected assembly or office. Voting rules are thus among the principal building blocks of representative democracy. They establish the most fundamental theoretical and empirical links between public preferences, political representation, and, ideally, government formation and policy making. Thus, the political consequences of alternative voting rules have always concerned political scientists. Both majoritarian and proportional voting rules exert profound effects on alleged political efficiency (i.e., the format and the fragmentation and polarization of political party systems and their propensity for sustaining single-party or coalition governments) and for different modes of formal and substantive political representation (i.e., the distortion of vote shares and seat shares and the representation of the median voter in parliament, in government, or actually in enacted policies).

The study of voting rules and their respective consequences belongs to the very core of comparative political research. As illustrated by William H. Riker, research on voting rules and electoral behavior has been organized as a cumulative science. In theoretical and conceptual terms, the arguments have advanced from the early, inductive reasoning by John Stuart Mill, Henry Droop, or Thomas Hare toward the codification of Duverger's law and hypothesis, thereafter toward their refinement by scholars such as Giovanni Sartori or Rein Taagepera, and, more recently, toward the sophisticated, game-theoretical treatment by Gary W. Cox. Further research extended the scope of the analyses so as to also consider the additive effect of social structure or direct presidential elections and, most important, the interactive effects of institutional structure and political cleavages.