Models of coalition politics: recent developments and new directions

Coalition bargaining is at the heart of politics in most parliamentary democracies. Given the prevalence of coalition governments, it is not surprising that understanding how they form, and how coalescing parties distribute the various spoils of office between them, has been a central research program in political science for several decades. This has led to the development of a rich tradition of formal, deductive models of coalition bargaining. We review theoretical developments in this literature resulting from the introduction of the "new institutionalism" in the 1990s. We argue that the models that have emerged can usefully be classied into those that adopt a non-cooperative game-theoretic framework and those that eschew strong assumptions about bargaining protocols and instead focus on background constraints that limit the viability of potential governments. We sketch the strengths and limitations of each approach, and point towards avenues for future theoretical development.