Community Notes (formerly known as Birdwatch), developed by X/Twitter, is a crowd-based fact-checking solution designed to fight against misleading content, especially fake news. Accepted users participate in Community Notes by rating existing notes as helpful, somewhat helpful, and not helpful. Users themselves are also rated on their own helpfulness by matching how they rate with the outcome of the notes. Instead of calculating simply an average score from people’s votes, Community Notes uses a Matrix Factorization algorithm to identify notes that are helpful regardless of people’s political biases by introducing a “polarity” dimension to rate both users and notes. A more detailed explanation of the algorithm could be found here.
Advantages
- Effective Matrix Algorithm: The matrix algorithm is shown to be effective in preventing one-sided ratings based on majority and identifying consensus among politically polarized users.
- Open Source: The solution is open-source and users can download the note and rating data and run it themselves to see if the outputs correspond to what is actually on X/Twitter.
Limitations
- Incentive for Malicious Actors: Since only one note is selected for display for each potentially misleading tweet, there is a high incentive for malicious actors to reduce the rating of that note. They could attack the algorithm by downvoting that note to reduce its rating. Vitalik mentioned this issue in this article.
- Difficulty in Achieving Consensus: For a note to be made public, it needs to be generally accepted by people from across the entire political spectrum. Some have criticised that in a highly bipartisan environment, it is almost impossible to reach such consensus.
- Sybil Attacks: Without an efficient sybil-resistant authentication system, either using proof of identity or using online reputation or both, the algorithm can easily be manipulated by armies of bots or trolls.
- Complex Algorithm: The Community Notes algorithm is particularly complex.
Could it be useful for our requirements?
Community Notes was primarily designed for combatting disinformation and fake news. Its primary role is not for in-depth deliberations, like with Polis. However, we are primarily focused on the latter. While it would be theoretically possible to utilise Community Notes for our purpose, it would require a lot of investigative work and potential modifications, and we are not sure at this point whether or not it will be useful, compared to Polis.