Moralistic Imagination of Two-dimensional Politics: Identity and Moral Correlates of Social Media Engagement

Political polarization in the United States is often framed as an ideological divide between the left and the right. However, emerging research highlights a second, orthogonal dimension: the divide between establishment and anti- establishment movements. While prior work emphasizes the role of morality in shaping political motivations along both dimensions, we extend this by examining how moral rhetoric structures intergroup dynamics within a two-dimensional political space. Using computational linguistic analysis on over 600,000 posts and comments from three representative political communities on Reddit (r/Trump, r/JoeBiden, and r/SandersForPresident), we investigate how moral foundations are invoked differently across these communities. Our results show that anti-establishment communities exhibit consistently higher levels of moral expression than their establishment counterparts. Yet, patterns of engagement suggest that ideological identity—more than anti-establishment alignment—continues to anchor online political engagement. This study contributes a novel computational framework for mapping social identity dynamics in online political communication. Theoretically, it deepens our understanding of how emerging political identities interact with the ideological divide, revealing that while anti-establishment movements may reshape rhetorical styles, the ideological divide remains the primary axis of online political engagement.