When I spoke to some of the researchers whose work had been included, I found a combination of broad, visceral unease with the current situation—with the banefulness of harassment and trolling; with the opacity of the platforms; with, well, the widespread presentiment that of course social media is in many ways bad—and a contrastive sense that it might not be catastrophically bad in some of the specific ways that many of us have come to take for granted as true. This was not mere contrarianism, and there was no trace of gleeful mythbusting; the issue was important enough to get right. When I told Bail that the upshot seemed to me to be that exactly nothing was unambiguously clear, he suggested that there was at least some firm ground. He sounded a bit less apocalyptic than Haidt.

“A lot of the stories out there are just wrong,” he told me. “The political echo chamber has been massively overstated. Maybe it’s three to five per cent of people who are properly in an echo chamber.” Echo chambers, as hotboxes of confirmation bias, are counterproductive for democracy. But research indicates that most of us are actually exposed to a wider range of views on social media than we are in real life, where our social networks—in the original use of the term—are rarely heterogeneous. (Haidt told me that this was an issue on which the Google Doc changed his mind; he became convinced that echo chambers probably aren’t as widespread a problem as he’d once imagined.) And too much of a focus on our intuitions about social media’s echo-chamber effect could obscure the relevant counterfactual: a conservative might abandon Twitter only to watch more Fox News. “Stepping outside your echo chamber is supposed to make you moderate, but maybe it makes you more extreme,” Bail said. The research is inchoate and ongoing, and it’s difficult to say anything on the topic with absolute certainty. But this was, in part, Bail’s point: we ought to be less sure about the particular impacts of social media.