Explaining the multiparty systems of Western Europe prior to the adoption of proportional representation

The literature has difficulty explaining why the number of parties in majoritarian electoral systems often exceeds the two-party predictions associated with Duverger’s Law. To understand why this is the case, I examine several party systems in Western Europe before the adoption of proportional representation. Drawing from the social cleavage approach, I argue that the emergence of multiparty systems was because of the development of the class cleavage, which provided a base of voters sizeable enough to support third parties. However, in countries where the class cleavage became the largest cleavage, the class divide displaced other cleavages and the number of parties began to converge on two. The results show that the effect of the class cleavage was nonlinear, producing the greatest party system fragmentation in countries where class cleavages were present – but not dominant – and smaller in countries where class cleavages were either dominant or non-existent.