The ‘Law of Conservation of Disproportionality’ and Electoral Prospects of Small Parties

Abstract

Electoral systems have well known implications for party systems in general and the creation and representation of small parties in particular: while proportional representation (PR) favours small parties’ electoral success, large parties tend to benefit from first past the post majoritarian electoral systems. However, it has been observed that small parties more easily form in PR systems, but also tend to be less successful in PR elections in the long run. These seemingly contradictory observations might be explained by the conservation of disproportionality that electoral systems bring with them Instead of fostering the electoral success of small parties, PR might prevent parties and voters from strategic coordination and thus punish small parties. In order to investigate the question whether conservation of disproportionality occurs and discriminates against small parties more than we would expect, I theoretically derive particular temporal patterns of development of disproportionality and analyse data on electoral system change from 10 Central and Eastern European democracies. I show that there is some evidence that conservation of disproportionality occurs. However, it is not possible to draw a direct line from electoral system change to the electoral success of small parties.