For years, social media companies have relied on an impenetrable first amendment protection to shield them from legal claims that their products are dangerous to children. But now, a cluster of plaintiffs are trying a different tact. Cecilia Kang, who covers technology, explains why these new lawsuits pose an existential threat to social media giants, and how those companies are likely to defend themselves. Guest: Cecilia Kang, a reporter covering technology and regulatory policy for The New York Times. Background reading: Here’s what to know about the social media add...