Dynamics of strategic three-choice voting

¹  Center for Polymer Studies and Department of Physics, Boston University - Boston, MA 02215, USA
²  Department of Applied Mathematics, School of Mathematics, University of Leeds - Leeds LS2 9JT, UK, EU
³  Mathematics Institute & Warwick Centre for Complexity Science, The University of Warwick Coventry CV4 7AL, UK, EU

Corresponding author: redner@bu.edu

Received: 9 December 2008
Accepted: 6 February 2009

Abstract

In certain parliamentary democracies, there are two major parties that move in and out of power every few elections, and a third minority party that essentially never governs. We present a simple model to account for this phenomenon, in which minority party supporters sometimes vote ideologically (for their party) and sometimes strategically (against the party they like the least). The competition between these disparate tendencies reproduces the empirical observation of two parties that frequently exchange majority status and a third party that is almost always in the minority.