We are in the midst of a public conversation about whether social media echo chambers facilitate the spreading of fake news or prevent constructive dialogue on public issues. In a recent interview with The Washington Post, Twitter CEO Jack Dorsey said that he was experimenting with features to reduce echo chambers on Twitter by inserting content with alternative viewpoints into people’s feeds. In response, an op-ed in The New York Times predicted that this idea would backfire, citing recent research showing that exposing people to alternate viewpoints only makes them more partisan. The problem with this otherwise important debate is that it assumes that Twitter users exist in echo chambers in the first place. They don’t.