Whose tweets? The rhetorical functions of social media use in developing the Black Lives Matter movement.

Research on collective action frequently characterizes social media as a tool for mobilization. However, social media activity can fulfil a variety of different functions for social change. In particular, the rhetorical functions of social media use by social movements are not well understood. We address this shortfall by analysing the rhetorical functions of Twitter use during an early stage of the Black Lives Matter social movement. We examine how activists used Twitter to balance competing aims for social change, such as growing the movement beyond disadvantaged-group members, while preventing appropriation or dilution of their message by advantaged-group 'allies'. We find that although Twitter users promote different, and often competing, definitions of the issues that the movement represents, rhetorical strategies are used to advance inclusive definitions that focus on racism. When activists address alternative definitions of movement actors and issues, representations of Otherness are used to characterize the proponents of these definitions as in opposition to the movement. Finally, we find that one way of resolving the tension between growing the movement and promoting disadvantaged-group control is by using identity and technology resources to explicitly define (1) how different groups can be movement advocates, and (2) action strategies for social change.