Threats to the sustainability of Community Notes on X

Community Notes are emerging as an important option for content moderation. The Community Notes system pioneered by Twitter, now known as X, uses a bridging algorithm to identify user-generated context with upvotes across political divides, supposedly spinning consensual gold from partisan straw. It is important to understand the nature of the community behind Community Notes, especially as the feature has now been imitated by several billion-user platforms. We look for signs of stability and disruption in the X Community Notes community and interrogate the motivations other than partisan animus (Allen, Martel, and Rand 2022) which may be driving users to contribute. We conduct a novel analysis of the impact of having a note published, which requires being considered "helpful" by the bridging algorithm, utilising a regression discontinuity design. This allows stronger causal inference than conventional methods used with observational data. Our analysis shows the positive effect on future note authoring of having a note published. This highlights the risk of the current system, where the proportion of notes considered "helpful" (and therefore shown to users on X) is low, 10%, and declining. This analysis has implications for the future of Community Notes on X and the extension of this approach to other platforms.