In political science, Duverger's law is a principle which states that plurality-rule elections (such as 'First Past the Post') structured within single-member districts tend to favor a two-party system, and that "the double ballot majority system and proportional representation tend to favor multipartism." The discovery of this tendency is attributed to Maurice Duverger, a French sociologist who observed the effect and recorded it in several papers published in the 1950s and 1960s. In the course of further research, other political scientists began calling the effect a "law" or principle. Duverger...