Divide and Diverge

Abstract

This paper shows that competing political parties can benefit from polarization. I study a probabilistic voting model with ex-ante identical parties and decreasing marginal utility from political power. In equilibrium, parties offer different platforms: by targeting different voter blocks, they insure against electoral risk and stabilize power. With one policy dimension, each party gains when voters on opposite sides of the median become more divided, even if only the opponent's supporters become more extreme. With multiple dimensions, parties gain from ideological coherence, the alignment of disagreement across issues. The results speak to polarizing communication, party identity, and electoral institutions.