Top monotonicity: A common root for single peakedness, single crossing and the median voter result

When members of a voting body exhibit single peaked preferences, pair-wise majority voting equilibria (Condorcet winners) always exist. Moreover, they coincide with the median(s) of the voters’most preferred alternatives. This important result, known as the median voter result, has been crucial in the development of public economics and political economy. Yet, there are many examples in the literature where We thank Pablo Amorós, Dolors Berga, Carmen Beviá, Luis Corchón, Matthew Jackson, Hervé Moulin, Antonio Nicoló, Josep E. Peris, Alejandro Saporiti and William Thomson for helpful comments and suggestions. A special mention goes for Miguel Angel Ballester, whose careful and insightful comments have been decisive in shaping the paper. Salvador Barberà gratefully acknowledges support from the Spanish Ministry of Science and Innovation through grant "Consolidated Group-C" ECO2008-04756, and by the Generalitat de Catalunya, Departament d’Universitats, Recerca i Societat de la Informació through the Distinció per a la Promoció de la Recerca Universitària, grant SGR2009-0419 and the Barcelona GSE Research Network. Bernardo Moreno gratefully acknowledges …nancial support from Junta de Andalucia through grant SEJ522 and the Spanish Ministry of Science and Technology through grant SEC2008-03674. yCorresponding author : MOVE, Universitat Autònoma de Barcelona and Barcelona GSE, Edi…ci B, 08193 Bellaterra, Spain. E-mail: [email protected] zDepartamento de Teoría e Historia Económica, Facultad de Ciencias Económicas y Empresariales, Campus de El Ejido, 29071 Málaga, Spain. E-mail: [email protected]