Coalition Governments

Today we have a guest post from Joseph W. Roberts, associate professor in the Department of Politics and International Relations at Roger Williams University. He can be contacted at jroberts [at] rwu [dot] edu.

Recently someone on Twitter asked about teaching coalition governments and their formation in an introduction to comparative politics class. I responded to the query with an exercise that I use to demonstrate presidential vs. parliamentary systems and voting systems. The exercise demonstrates why a state might choose one system over another in a way the mirrors the perspective championed by Lijphart (references listed below).

I begin by talking to the students about the size principle and the minimum winning coalition described by Riker and the critiques about whether a minimum winning coalition of two parties with a “margin” of one is actually stable (see Shepsle, Butterworth, or Brown). I explain ways in which party identity/ideology can affect the creation of coalitions, and ask students to think of other factors, such as ethnic identity, that might be part of the process. This subject is usually covered briefly in comparative politics textbooks and I just reinforce some of the basic concepts.

I then use the actual party data from an election available from Wikipedia—usually Israel because it has a lot of elections—but any election where a coalition government is formed will work. I give the students the list of parties that received seats in the election, a rough description of each party’s ideology, and a number line showing where each party fits in the left-right political spectrum, as shown in the table below.

Two caveats are in order. First, the rough ideology is far from perfect in its characterization of the parties, but I explain to students that we are not looking at the specifics of the Israeli political system but are instead using it as an example. Second, the number line is also not perfect because it assumes that the different parties are equally spaced on the continuum from left to right. Again, I explain to students that this is not meant to reflect a true ideological spectrum but is used merely for convenience. A longer, follow up discussion on the intricacies of a country’s political spectrum can be held in a subsequent class session if desired.

Once the students have a basic understanding of the data that I have given them, I divide the class proportional to the party affiliation. I calculate how many students belong in each party beforehand. For a class of thirty, for example, the student groups would be 10/9/4/2/2/1/1/1 in order from Likud to Yamina. If, for example, three students are absent, I reduce membership in each of the three largest parties by one student. I then tell students to create a coalition government that guarantees a parliamentary majority in the class—in a class of thirty, the minimum coalition size is sixteen. I usually give students 20-30 minutes to work through possible coalitions and see how they might play out. Once they create a coalition, we discuss why it might succeed or fail and how it compares to the real government that formed after the election.

When the division of a small class proportionally into parties would result in the number of seats won by some parties shrinking to zero, I break the students into groups that represent the leaders of each party, and each party’s leadership controls number of seats that is proportional to the election results; i.e., from the table above, 36, 33, and 15 seats, and so on. The class is still tasked with forming a coalition government.

The exercise not only gets students to think about the difficulty of creating a coalition, but it also gives them a sense of outsized role minority parties can play in a coalition government. The Israeli case is particularly useful in this regard because far-right parties, while smaller, can exert enormous influence by threatening to withdraw from the coalition if their demands are not met. This is a ripe area for conversation as well.


Browne, Eric. “Testing Theories of Coalition Formation in the European Context.” Comparative Politics 3, 4 (1971): 391–421. doi:10.1177/001041407100300401.

Butterworth, Robert. “Comment on Shepsle’s ‘On the Size of Winning Coalitions.’” The American Political Science Review 68, 2 (June 1974): 519–521. doi:10.2307/1959500.

Lijphart, Arend. Patterns of Democracy: Government Forms and Performance in Thirty-Six Countries. New Haven: Yale University Press, 1999.

Riker, William. The Theory of Political Coalitions. New Haven and London: Yale University Press, 1962

Shepsle, Kenneth. “On the Size of Winning Coalitions.” The American Political Science Review 68, 2 (June 1974): 519–521. doi:10.2307/1959499.