Keep the trolls on Facebook

EVERY election year, I witness an unfriending frenzy unfold on my Facebook feed. In 2016, it was mostly my American friends who were on a purging rampage - "If you're dumb enough to vote for Trump, you're really not worth my time" - the year before, it was my fellow countrymen.

The patterns are similar: Friend A posts about a deeply divisive topic - say, immigration, abortion, or transgender issues. Friend B takes umbrage at Friend A's point-of-view and removes her from his friends list. Friend B then posts about the purge, declaring …