"Social media are a little peculiar in that they literally are delivered by a personalized feed computed by an algorithm, so quite literally what you’re seeing, no one else is seeing exactly that feed. On the other hand, any given post could be common knowledge for all you know, especially if it’s in a trending column, and because of virality—that is, someone could repost or like a post, which could cause still other people to like it in a chain reaction—anything could become common knowledge, and uniquely to social media, you can generate common knowledge. Your post might go viral. So this, and the fact that there are a small number of social media platforms—and often newcomers don’t take off for that reason, the incumbent already is the town square—which is why Bluesky is a tiny fraction of the size of X: when people go to X, they have some chance of seeing what everyone else is seeing, or that everyone else will see what they’re posting. And even mainstream media actually report, often, screen grabs of tweets, so it really can become common knowledge. That gives rise to a peculiar dynamic that relates to norms." Clip on social media and common knowledge, the topic of my new book, is from an interview with Robert Contofalsky (@CR_Scholar) of R-Academy. -- When Everyone Knows That Everyone Knows . . .: Common Knowledge and the Mysteries of Money, Power, and Everyday Life: