The Case for Responsible Parties∗

Electoral platform convergence is perceived unfavorably by both the popular press and many academic scholars. Arguably, “it does not provide enough choice” between candidates (Committee on Political Parties, 1950). This paper provides a formal account of the perceived negative effects of platform convergence. We show that when parties do not know voters’ preferences precisely, all voters ex-ante prefer some platform divergence to convergence at the ex-ante median. After characterizing the unique symmetric equilibrium of competition between responsible (policy-motivated) parties, we conclude that all voters ex-ante prefer responsible parties to opportunistic (purely office-motivated) ones when parties are sufficiently ideologically polarized that platforms diverge, but not so polarized that they diverge excessively. However, greater polarization increases the scope for office benefits as an instrument for institutional design: We calculate the socially-optimal level of platform divergence and show that office benefits can be used to achieve this first-best outcome, if parties are sufficiently ideologically polarized. ∗We thank Becky Morton, Michael Peress, and Joao Santos for valuable conversations. All mistakes are our own. †Department of Economics, University of Illinois, 1206 S. Sixth Street, Champaign, IL 61820, USA. ‡W. Allen Wallis Institute of Political Economy, University of Rochester, Rochester, NY 14627, USA. §Department of Economics, University of Essex, Wivenhoe Park, Colchester, Essex CO4 3SQ, United Kingdom presented by Dan Bernhardt FRIDAY, Nov. 13, 2009 1:30 pm 3:00 pm, Room: ACC-201 USC FBE APPLIED ECONOMICS WORKSHOP