So even if social media really did begin to undermine democracy (and institutional trust and teen mental health) in the early 2010s, we should not expect social science to “settle” the matter until the 2030s. These three studies cannot prove that social media caused the global decline, but—contra Meta and Zuckerberg—they show a global trend toward polarization in the previous decade, the one in which the world embraced social media. Because conflicting studies are common in social-science research, I created a “collaborative review” document last year with Chris Bail, a sociologist at Duke University who studies social media.