Coalition Formation Along Informal Ties: A Network Model

Political coalitions are usually thought to form along common interests or shared political views. But especially in authoritarian regimes, personal connections appear to play an equal, if not more important role. Their positions in this informal network can thus provide actors with considerable power in this environment without external enforcer, where alliances have to be enforced in a decentralized fashion. This paper presents a model in which leaders try to form a majority coalition along network ties among relevant political actors. Simulations on random networks and real-life Chinese patronage networks illustrate how all but the regular (lattice or complete) network lead to power differentials between the actors. The model identifies three specific network positions: those that increase the chances of entering the majority coalition, those that enable coalition leaders to remain in charge of the coalition, and those that help a ruler fend of the opposition. I discuss their respective properties, and I show that powerful members of the Chinese Communist Party (the future members of the inner circle and the current grey eminences) do indeed hold the positions that the model would predict. Exploring the model further, I show that with two competing leaders, the network structure endogenously reduces the coalition size necessary to win a struggle against any competitor. This may explain why autocrats can rule with the help of a relatively small segment of the population. I also examine which members of his or her coalition are particularly important to maintain the coalition, and which ones are more expendable (and hence vulnerable to a purge). While I test the model empirically only on the political elite of the Chinese Communist Party 1982-2012, the model seems applicable also to alliance formation in other contexts without external enforcers, such as the international stage.