Ideology and Existence of 50%-Majority Equilibria in Multidimensional Spatial Voting Models

22 Pages Posted: 16 Oct 2008  

Hervé Cres

HEC Paris

M. Utku Ünver

Boston College - Department of Economics

Date Written: September 17, 2008

Abstract

When aggregating individual preferences through the majority rule in an n-dimensional spatial voting model, the 'worst-case' scenario is a social choice configuration where no political equilibrium exists unless a super majority rate as high as 1-1/n is adopted. In this paper we assume that a lower d-dimensional (d < n) linear map spans the possible candidates' platforms. These d 'ideological' dimensions imply some linkages between the n political issues. We randomize over these linkages and show that there almost surely exists a 50%-majority equilibrium in the above worst-case scenario, when n grows to infinity. Moreover the equilibrium is the mean voter. The speed of convergence (toward 50%) of the super majority rate guaranteeing existence of equilibrium is computed for d=1 and 2.

Suggested Citation

Cres, Hervé and Ünver, M. Utku, Ideology and Existence of 50%-Majority Equilibria in Multidimensional Spatial Voting Models (September 17, 2008). Available at SSRN: https://ssrn.com/abstract=1285182 or http://dx.doi.org/10.2139/ssrn.1285182

Hervé Cres

HEC Paris ( email )

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Utku Unver (Contact Author)

Boston College - Department of Economics ( email )

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HOME PAGE: http://www2.bc.edu/~unver

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