Sedimented Polarisation: Discourse, Materiality, and Moderation Co-Shaping the Political Reddit

This study examines political discourse across eleven major subreddits over sixteen years to understand the dynamics of cross-ideological interaction on Reddit. Through a framework combining discourse theory and new materialism, we analyse information-sharing, cross-posting, and discursive formations across political communities. Our findings lead us to conceptualise ‘sedimented polarisation’—a discursive-material condition where polarisation becomes an empty signifier around which political discursive formations take shape. Despite Reddit’s design allowing cross-community engagement, we find minimal interaction between discursively dissonant spaces. While r/politics is often presented as a space for cross-ideological deliberation and exposure, it fails to function as a town square. We observe a fragmentation across political subreddits and discourses beyond the left-right dichotomy. These patterns emerge from an entanglement of platform design, community moderation practices, user agency, discourses, and broader socio-political contexts.