There are two central facts about 21st-century U.S. politics. First, we suffer from asymmetric polarization: the Republican Party has become an extremist institution with little respect for traditional norms of any kind. Second, mainstream media – still the source of most political information for the great majority of Americans – haven’t been able to come to grips with this reality. Even in the age of Trump, they try desperately to be “balanced”, which in practice means bending over backwards to say undeserved nice things about Republicans and take undeserved swipes at Democrats.

This dynamic played a crucial role in last year’s election; it’s one of the reasons major news organizations devoted more time to Hillary Clinton’s emails than to all policy issues combined. But it has been going on for years. It’s the whole story of Paul Ryan’s career: journalists trying to be centrists desperately wanted to show their neutrality by praising a Serious, Honest, Conservative, and promoted Ryan into that role even though it was obvious from the beginning that he was a con man.

And it’s still playing out, as we can see from what looks like a looming debacle in Facebook’s efforts to institute fact-checking.