To how many politicians should government be left?

We study opinion formation processes in small social networks. In particular we show how a group’s ability for efficient decision-making depends on its size. We adopt a threshold voter model and show that there exists a characteristic size beyond which the probability of forming internal factions–and thus absence of consensus–undergoes a qualitative change. Our work is empirically motivated by an apparent correlation between the size of a decision-making group and its performance in the particular case of national governments.