Social Identity, Electoral Institutions and the Number of Candidates

The empirical literature in comparative politics holds that social cleavages affect the number of candidates or parties when electoral institutions are ‘permissive’, but it lacks a theoretical account of the strategic candidate entry and exit decisions that ultimately determine electoral coalitions in plural societies. This article incorporates citizen-candidate social identities into game-theoretic models of electoral competition under plurality and majority-runoff electoral rules, indicating 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. Empirical patterns in cross-national presidential election results are consistent with the theoretical model.