When a Movement Becomes a Party: Computational Assessment of New Forms of Political Organization in Social Media

Abstract

Social media has become a key mechanism for the organization of grassroots movements. In the 2015 Barcelona City Council election, Barcelona en Comú, an emerging grassroots party, was the most voted one. This candidacy was devised by activists involved in the Spanish 15M movement in order to turn citizen outrage into political change. On the one hand, the 15M movement is based on a decentralized structure. On the other hand, political science literature postulates that parties historically develop oligarchical leadership structures. This tension motivates us to examine whether Barcelona en Comú preserved a decentralized structure or adopted a conventional centralized organization. In this article we propose a computational framework to analyze the Twitter networks of the parties that ran for this election by measuring their hierarchical structure, small-world phenomenon and coreness. The results of our assessment show that in Barcelona en Comú two well-defined groups co-exist: a cluster dominated by the party leader and the collective accounts, and another cluster formed by the movement activists. While the former group is highly centralized like traditional parties, the latter one stands out for its decentralized, cohesive and resilient structure.