Causation, lawhood and determinism in electoral systems research: why ‘Duverger’s law’ deserves to be called a law
In the 1950s, Maurice Duverger formulated several propositions connecting electoral systems and the number of political parties partaking in the election. For example, he put forward that a simple-majority single-ballot system favours the two-party system. This claim has been referred to as Duverger’s law. Throughout the years, there has been a lot of debate about whether this claim (and other generalisations in the social sciences) deserves to be called a ‘law’. In this paper, we defend the view that Duverger’s law does deserve to be called a law. To argue for this, we present an account of lawhood based on the work of the philosopher Sandra Mitchell. In this account, the criterion for lawhood is spatio-temporal stability (and not, for example, determinism). We argue that spatio-temporal stability is the reason that many of the laws of physics are considered laws. We then show that Duverger’s law is spatio-temporal in the same way that many of the laws of physics are. Correspondingly, we conclude that Duverger’s law deserves to be called a law, as much as many of the laws of physics deserve this title. We finish with a reflection on the difference between determinism and lawhood, and argue that they should be separated conceptually.
KeywordsElectoral systems Maurice Duverger Sandra Mitchell Scientific laws
The authors thank Leen De Vreese, Bert Leuridan, Dingmar van Eck and two anonymous referees for comments on earlier versions of this paper. Inge De Bal is research assistant of the FWO (Research Foundation—Flanders).
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