Facebook keeps downplaying its own research and lawmakers aren't buying it

Yet another Facebook official just spent hours being grilled by members of Congress about the company's policies, and whether or not it does enough to protect some of its most vulnerable users. And once again, the Facebook executive -- today it was Head of Safety Antigone Davis -- seemed to do her best to dodge the most difficult questions. But the latest hearing on teen mental health, which came in response to reporting from The WSJ, was different from past hearings. That's because, thanks to a...