Duvergerian equilibrium

In his 1954 book, "Political Parties", Maurice Duverger postulated a relationship between electoral regime and the number of political parties. In particular, he attempted to show that political parties in countries using the first past the post system tended to converge on two ideological poles, whereas countries using proportional representation tended to have several political parties forming coalition governments in the center. This thesis has been subject to much attention and criticism since it was published.

References

* [http://www.ingentaconnect.com/content/pal/14763427/2005/00000003/00000003/art00007 A Short Biography of Maurice Duverger]