Dehghan, E., Carlon, D., Kasianenko, K., Nagappa, A., & Suresh, V. P. (2026). The entangled dynamics leading to the sedimentation of polarisation on political Reddit. Figshare, 1–24. https://doi.org/10.6084/m9.figshare.31275028
Summary
This paper investigates cross-ideological communication across 11 major political subreddits over 16 years, combining quantitative overlap measures with corpus-assisted discourse analysis and thematic coding of moderation practices. The authors find vanishingly small overlaps in users, sources, cross-posts, and cross-comments — even between discursively similar communities — and reject the common framing of r/politics as a cross-ideological “town square.” They advance the concept of sedimentation of polarisation: polarization is not the output of toxic discourse or algorithmic sorting alone, but a discursive-digital precondition arising from the entanglement of platform design, moderation, user agency, discourse, and socio-political context.
Key Contributions
- Introduces sedimentation of polarisation — drawing on Laclau — as polarization treated as precondition rather than outcome of subreddit communication.
- Develops the Normalised Similarity Score (NSS), comparing observed cross-community overlaps to expectations based on contribution rates and contributor counts.
- Provides large-scale empirical evidence that r/politics is not a bridging public sphere, complicating prior characterisations of it as left-leaning or deliberative.
- Extends polarization research beyond the left–right binary by documenting fragmentation among ideologically aligned subreddits (e.g., r/Conservative vs. r/conservatives).
- Articulates a non-hierarchical discursive-digital entanglement framework integrating platform materiality, moderation, agency, and discourse.
- Contributes to the comparatively thin empirical literature on Reddit as a political communication space.
Methods
Mixed-methods analysis of 16 years of submissions and comments from 11 political subreddits (r/politics, r/Conservative, r/conservatives, r/Republican, r/republicans, r/Libertarian, r/Liberal, r/democrats, r/progressive, r/DemocraticSocialism, r/esist). Overlaps were measured across shared domains, shared URLs, linked subreddits, cross-submitters, and cross-commenters using the NSS. Discourse was analysed via keyness (log-likelihood) in AntConc 4.3.1 with r/politics as the reference corpus. Two coders thematically analysed subreddit descriptions, rules widgets, and wikis to map moderation features (including AutoModerator configurations).
Findings
- No subreddit pair reached NSS ≥ 1.0 on shared domains; the highest pairing was r/progressive–r/DemocraticSocialism at 0.879.
- URL-level overlaps collapsed compared to domain-level overlaps (e.g., the same pair dropped to 0.094) — communities draw from overlapping sources but circulate different stories.
- Cross-posting never exceeded NSS = 0.206 and cross-commenting never exceeded 0.280; users rarely leave their homebase subreddit.
- r/politics shows uniformly low overlaps with both left- and right-leaning subreddits, undermining its framing as a cross-ideological hub or a clearly left-biased space.
- Right-leaning subreddits cohere around shared antagonists (“woke,” “the left,” “cancel culture”); left-leaning subreddits are more topically heterogeneous (guns, gender, electoral politics, economic critique, anti-Trump resistance).
- Strict civility moderation (r/Liberal, r/Republican) suppresses derogatory language; loosely moderated spaces (r/republicans) feature loaded terms like “libtards.”
- Intra-ideological splits — e.g., r/conservatives as a “minimally moderated” offshoot of r/Conservative — show that moderation conflicts themselves generate polarization.
Connections
This paper contributes to a Reddit-focused empirical literature that remains relatively sparse next to Twitter/Facebook work, and its critique of the cross-ideological “town square” thesis speaks directly to debates about exposure and echo chambers carried out on other platforms in Bakshy2015-rn and Gonzalez-Bailon2024-rq. Its insistence that platform affordances and moderation co-constitute polarization resonates with platform-materialist accounts such as Munger2025-cz and with work on community/moderation dynamics shaping political talk like Rossini2026-jn. The “sedimentation” argument — polarization as precondition rather than emergent outcome — offers a useful counterpoint to discourse- or affect-centric framings such as Brady2026-ln.
Podcast
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