Ideology and Competence in Alternative Electoral Systems . ∗

We develop a model of elections in proportional (PR) and majoritarian (FPTP) electoral systems. The model allows an endogenous number of candidates, differentiation in a private value dimension, or ideology, and in a common value dimension, which we interpret broadly as quality or competence. Voters are fully rational and strategic. We show that the quality of candidates running for office in PR elections is lower than that of any candidate running for office in FPTP, and that in all equilibria in which candidates are ideologically differentiated, the number of candidates running for office is larger than in majoritarian electoral systems (where exactly two candidates run). Moreover, we provide conditions under which the rankings are strict. We consider several extensions of the model, which include introducing majority premiums in PR, thresholds for representation, and multiple electoral districts. ∗We thank Juan Carrillo, Federico Echenique, Zucchero Fornaciari, Daniela Iorio, Alessandro Lizzeri, Jean-Laurent Rosenthal, and seminar participants at Caltech, Northwestern, Princeton, USC, the Workshop on the Political Economy of Democracy, the MPSA annual meeting, and the North American Summer Meeting of the Econometric Society, for helpful comments to previous versions of this paper. Mattozzi acknowledges financial support from the National Science Foundation. †Division of Humanities and Social Sciences, California Institute of Technology, Pasadena, California 91125, USA, emails: [email protected], [email protected]