Maurice Duverger is arguably the most distinguished French political scientist of the last century, but his major impact has, strangely enough, been largely in the English-speaking world. His book, Political Parties, first translated into English in 1954, has been very influential in both the party politics literature (which continues to make use of his typology of party organization) and in the electoral systems literature. His chief contributions there deal with what have come to be called in his honor Duverger's Law and Duverger's Hypothesis. The first argues that countries with...