Something is wrong with the American Left. The recent spate of violent protests on college campuses has been well-documented, but the violence and intolerance championed by left-wing student activists is beginning to creep off campus and into mainstream public life.

The reason for this is straightforward enough: although progressives pride themselves on their putative tolerance and diversity, the imperatives of leftist politics are fundamentally illiberal. Justice imposed through power is the philosophical foundation of the political left, and when earnest progressives become convinced the only avenue to power is violence, their tolerance quickly falls by the wayside. Consider a few recent events, none of which involved college protesters but all of which were marked by threats of violence.

Ahead of a town hall meeting this week in Virginia’s fifth congressional district, Republican Rep. Tom Garrett received a series of disturbing threats—not just against him but also his wife and family, even his dog. One message said bluntly, “This is how we’re going to kill your wife.”