A Theory of Split-Ticket Voting: Biased Politicians as Contestants

抄録

This paper presents a simple model to rationalize split-ticket voting observed in a presidential political system. The rationale is new in that, in contrast to the “ideological moderation” explanation of previous literature, it focuses on the incentive effect of “ideological polarization” by splitting tickets. More specifically, we assume that political parties compete for votes not only in the ideological position of policy, but also in the quality of policy, the improvement of which requires costly efforts. Under this circumstance, if the executive and the legislature are elected from the same party, they behave as free-riders since, due to the congruence of interest in the ideological dimension, they engage in a “team production” of a high-quality policy; meanwhile, if they are elected from different parties, they behave as contestants since, due to the conflict of interest, they engage in a “competitive production” of a high-quality policy. Taking this incentive effect into account, voters rationally vote for candidates from different parties for the executive and for the legislature and, as a consequence of this, the elected candidates cannot be centrists but should be biased. Specifically, voters want the ideological divergence of the executive and the legislature to be maximal to promote incentives but want the ideological positions of the executive and the legislature to be closest to the median to well represent social preference. Then, to balance the two requirements, voters simultaneously appoint a moderate right and a moderate left to one office and to another. Our model also predicts that a parliamentary political system, where the ideology of the executive and that of the legislature institutionally coincide, tends to yield a policy outcome with better representation of the median preference but with lower quality.