Center Parties and Systemic Polarization

Abstract

This paper argues that strong center parties may lead to polarization, not moderation, and that we must reassess our assumptions regarding their contribution to healthy democratic systems. The relationship between the parliamentary strength of center parties and the level of party system polarization is examined with electoral data from 10 Western European countries between 1979 and 1989. The results show that as the center's share of parliamentary seats increases, this convergence of voters is offset by another concurrent trend which keeps the level of party system polarization constant. Two theoretical explanations are posited: as the center parties expand either the extremist parties increase as well, or an outward movement of parties takes place. Both theoretical explanations are tested empirically, and both are validated. The paper concludes with a theoretical assessment of these findings - and the crucial differences between the two explanations - for electoral competition, governmental durability, and democratic stability.