 There remains a notable gap online between the prevalence of democratic discourse and debate—which require only the open voicing of opinions and reasons, respectively—and the relative absence of democratic deliberation, which requires the joint exercise of collective intentions, cooperation and compromise as well as a shared sense of reality on which to act. The greatest moral challenges of our time—responding to the climate change crisis, developing sustainable patterns of economic and social life, managing global threats to public health—aren’t going to be solved by ideological warfare but by deliberative, coordinated exercise of public wisdom. Today’s social media platforms are great for cultivating the former; for the latter, not so much.