Social Identity, Electoral Institutions, and the Number of Candidates

The existing empirical literature in comparative politics holds that social cleavages affect the number of candidates or parties when electoral institutions are “permissive.” However, this literature lacks a theoretical account of the strategic candidate entry and exit decisions that ultimately determine electoral coalitions under different institutions in plural societies. This paper incorporates citizen-candidate social identities into game-theoretic models of electoral competition under both plurality and majority-runoff electoral rules. Our theoretical results indicate that social group demographics can affect the equilibrium number of candidates, even in non-permissive systems. Under plurality rule, the relationship between social homogeneity and the effective number of candidates is non-monotonic and, contrary to the prevailing Duvergerian intuition, for some demographic configurations even the effective number of candidates cannot be near two. We find empirical patterns in cross-national data on presidential election results that are consistent with key intuitions derived from the formal model.