Megan McArdle: “Will is a friend, so naturally I’m dismayed by what happened. I’m also dismayed that it should have happened at Niskanen, a center-to-leftish institution I admire. And I’m even more worried to have yet another example of the damage Twitter is doing to American discourse — damage so profound that I’m beginning to think that the only way to fix it is not to urge tolerance, but for major institutions in the media and think-tank world to tell their employees to get the hell off Twitter.”