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Proportional Representation, Majoritarian Legislatures, and Coalitional Voting


  • I thank Shaun Bowler, Steve Callander, Raymond Duch, John Duggan, Mark Fey, Justin Fox, Rob Franzese, Christopher Kam, Renan Levine, panel participants at the general conference of the ECPR, the LSE Designing Democratic Institutions Conference, and the Modeling Context in the Vote Decision Conference at Nuffield College, Oxford, as well as seminar participants at the Tinbergen Institute, Rotterdam, and the Institute for Mathematical Behavioral Science, University of California–Irvine for useful comments and suggestions. I am grateful for financial support from the Icelandic Research Fund.

Indridi H. Indridason is Associate Professor of Political Science, 900 University Avenue, University of California, Riverside, Riverside, CA 92521 (


Voters in elections under plurality rule face relatively straightforward incentives. In proportional representation systems, voters face more complex incentives as electoral outcomes don’t translate as directly into policy outcomes as in plurality rule elections. A common approach is to assume electoral outcomes translate into policy as a vote-weighted average of all party platforms. However, most of the world’s legislatures are majoritarian institutions, and elections in PR systems are generally followed by a process of coalition formation. Results obtained using this assumption are not robust to the introduction of even minimal forms of majoritarianism. Incentives to engage in strategic voting depend on considerations about the coalitions that may form after the election, and the voters’ equilibrium strategies are shaped by policy balancing and the postelectoral coalition bargaining situation, including considerations about who will be appointed the formateur.