Coalition Opportunity Structures and the Belief Homophily Hypothesis

In the history of the Advocacy Coalition Framework (ACF), a major change was the addition of the concept of coalition opportunity structures. The concept was added in order to take into account differences in the institutional context in which coalitions operate, in particular the difference between pluralist and corporatist institutions. The basic tenet of the ACF is the belief homophily thesis according to which policy actors coordinate their action with other actors that share their policy core beliefs. We argue that a major implication of the idea of coalition opportunity structures is that the extent of belief homophily may vary depending on the coalition opportunity structures that have to do with institutional differences of different countries. We propose that corporatist institutions make it likely that coordination of action is less dependent on belief homophily because such institutions entail broad-based collaboration across the political spectrum. We test this idea with data of the climate change policy subsystems of eight countries that vary in their extent of pluralism/corporatism according to Lijphart’s index. A correlation analysis reveals that the more corporatist a country is, the less likely is it that actors coordinate their action exclusively with likeminded actors. In addition, a multilevel structural modelling (SEM) reveals that belief homophily is more important in pluralist countries but in these countries actors also collaborate with actors that are seen as influential. Interestingly, this influence effect also introduces a certain amount of dissimilarity into the beliefs of the actors with whom action is coordinated. We interpret these findings as implying that broad-based collaboration is more important in corporatist countries, whereas belief homophily but also so-called power politics is essential in pluralist cases.