Duverger's law and the study of electoral systems

Since its first publication in 1951, Duverger's Political Parties has influenced an entire branch of political science devoted to the study of the political consequences of electoral laws. This essay examines the two propositions known as Duverger's law and Duverger's hypothesis, both concerned with how electoral institutions shape party systems. First explaining the propositions and their context, the essay examines their influence on political science, and concludes by assessing where future research in the area might be best concentrated.