Published online by Cambridge University Press: 03 March 2020
In this paper, we study how political parties react to democratic transitions. We find that the structure of legislators’ social networks plays a critical role in shaping their political interactions during the transition period, and consequently, the post-transition party systems that emerge. We focus on the Korean case, where the incumbent authoritarian party merged with one of its pro-democracy opponents to create a powerful and enduring conservative party under democratic rule. Using a novel individual-level dataset on all legislative members during the transition, we find that the merger was facilitated by dense social networks linking members of the merged parties, which increased trust across the parties and reduced the difficulty of a merger. Conversely, we find that the paucity of ties linking pro-democracy parties hindered their long-term cooperation, despite their shared ideologies and policy goals. The study complements existing theories by providing a network-based explanation for the weakly institutionalized political party system that has characterized Korean politics since democratization.