Centripetal and Centrifugal Incentives in Electoral Systems

This paper investigates how electoral laws affect the position-taking incentives of parties and candidates. It seeks to extend the finding presented in the classical "median voter theorem" to a wide class of electoral systems--or to show the limits of such extension. The factors examined are the district magnitude, the electoral formula, the number of votes each voter is allowed to cast, whether voters can cumulate their votes, and whether voters can "partially abstain." I suggest a crude division of electoral systems into those producing predominantly centripetal incentives and those producing predominantly centrifugal incentives. Among the factors found to produce centripetal incentives, at least in noncumulative systems, are the following: increases in the number of votes per voter; outlawry of "partial abstention"; and decreases in the district magnitude. In systems allowing the cumulation of votes, matters are a bit different.