For the first dozen or so years of this century, and for some time before that, political violence on the home front was synonymous with jihadist terrorism masterminded by overseas organizations, or anti-capitalist street riots in the vicinity of G8 and other global leadership summits. Since then, the infamous polarization of national politics, which found a lightning-rod in the election of President Donald Trump, has given rise to some remarkably heated rhetoric. What has made it all the mor...
