In September 1864, the Association Internationale pour le Progrès des Sciences Sociales met in Amsterdam to examine the system of proportional representation (PR) which had just been proposed by Thomas Hare. The meeting signalled a growing interest in systems of PR across the more democratic nations of the world – some of which had already begun experimenting with it. Sixty years later, the majority of existing democracies, including Austria, Denmark, Finland, France, Germany, Ireland, Italy, Luxemburg, Malta, Netherlands, Norway, Sweden and Switzerland, had adopted PR for the election of their national legislatures.

Why did so many countries decide to shift to PR? Why did the shift occur at a given point in time, not earlier or later? Why did some countries never move to PR? These are the questions that we address in this Note.

We are interested in exploring the factors that influenced the decision to adopt PR at the turn of the twentieth century. We argue that two factors of considerable theoretical relevance were particularly important in facilitating the shift to PR: the spread of democratic ideas and the presence of a majority (usually two-round) system and, as a consequence, a multi-party system.

Carstairs's classic history of electoral systems shows that at the turn of the twentieth century there was a strong demand for PR, which was linked to a more general demand for democratization. As Carstairs notes,

there was a general movement in the direction of more democratic political institutions which took several different forms … There was a movement for the establishment or strengthening of parliamentary institutions … Extensions of the franchise for parliamentary elections enabled an increasingly large proportion of the population to gain representation in parliament … With these developments it became a matter of increasing concern that the elected members of parliament and the parties they supported should fairly represent the various interests and opinions of the electorate.