Duverger and the territory: explaining deviations from the two-party-competition-law

Abstract

According to Duverger's Law, plurality voting systems lead to two-party competition. However, many results of national parliamentary elections deviate from this rule. In contrast to previous research, which argues that in countries with territorial splits, regional two-party systems aggregate to national multi-party systems, this article shows that this explanation accounts for only a small proportion of the empirical exceptions to Duverger's Law. Instead, this article distinguishes three explanations for Non-Duvergerian outcomes at the national level. The three mechanisms relate to the level of electoral constituencies, to the aggregation of constituency results, and to the interaction between constituency-and aggregation effects. This article assesses the explanatory power of each of the three explanations on an extensive sample of election results from plurality vote systems, linking national to constituency-level results.

It’s Not Easy Being Green, White, Red, and Blue: Constituency Representations Versus Electoral Competition in the Wisconsin Green Party

“…Third parties simply will not be able to gain votes under FPTP as voters realize that their vote is often simply wasted, and even possibly risks letting a much-unfavoured candidate win. Recent work by Bochsler (2019) engages with criticism of the fact that Duverger's 'law' is anything but a law when considered globally and historically. However, his extensive data illustrates that word to be quite appropriate for use with respect to the US; elections in the U.S. being very consistent in conforming to Duverger.…”