Minority governments, minimal winning coalitions and surplus majorities in parliamentary systems

This paper studies government formation in parliamentary systems. A formal model is presented to explain the emergence of minority governments, minimal winning coalitions and surplus majorities, as a function of the largest party's share of the seats in the legislature and its location in the policy space. I conclude that as the largest party becomes larger and more central, the government changes from a surplus majority to a minimal winning coalition and from a minimal winning coalition to a minority government. I find empirical support for these conclusions in a study of government formation in eleven parliamentary democracies.