Flashbacks of 2016 in social media toxicity in politics

Emails of murky origins pop into public view, carrying a possible scent of foreign interference at a critical point of a U.S. presidential election. Bizarre conspiracy theories are posted and shared on social media. Twitter and Facebook, caught between being helpless conduit or gatekeeper of toxic disinformation, are whipsawed by the political winds.

The echoes of 2016 are unmistakable. Social media is flowing with outright falsehoods and dubious allegations — and, this time, the...