In mid-October, Twitter took the unprecedented step of preventing its users from sharing a link to a New York Post story reporting allegations about the Biden family’s foreign financial interests. Whenever controversies about social media censorship arise, a mantra is repeated in their defence, usually by progressives: these are private companies and, as such, they can regulate speech on their platforms however they wish. Notice that this claim does not simply maintain that companies can restrict information in pursuit of specific policy aims (like thwarting criminal activity such as human trafficking efforts or combating terrorist networks). Instead, they can restrict expression on their platforms simply because those platforms are company property. Among the most familiar responses to this argument is the view that, even though these tech giants are private entities, they function like public forums in which free expression should be upheld. Here, I spell out a different approach: that while social media companies are indeed private entities, they should nevertheless be unable to regulate non-criminal activity on their platforms for a variety of moral …