Models of electoral system change

Abstract

Electoral systems are commonly treated as exogenous determinants of political party systems, yet our theoretical understanding remains limited as to how these institutions themselves are determined. Part of the problem lies with the subject matter itself: electoral system change is frequently idiosyncratic, often occurring during episodes of exceptional political change. Yet another aspect of the problem is that explanations of electoral system change frequently occur piecemeal in application to specific cases, without systematic or comparative development. Addressing both problems, I first survey the existing literature to develop a comprehensive typology of explanations of electoral system change and persistence. I then set forth a theory predicting the conditions under which electoral systems should change, linking motivations for institutional change to instrumentally rational political parties seeking to maximize their legislative seat shares. The theory predicts that electoral laws will change when a coalition of parties exists such that each party in the coalition expects to gain more seats under an alternative electoral institution, and that also has sufficient power to effect this alternative through fiat given the rules for changing electoral laws. To contrast this model to other explanations of electoral system change, I point to its observable implications and outline how it could be confirmed or disconfirmed in empirical research. The comparison also highlights limitations in other approaches to explaining electoral system change, and underscores the importance of institutions in inducing equilibriums in both electoral systems and party systems.