There they go again. In San Jose last week, lefty demonstrators rioted against typical Americans leaving a Donald Trump rally, and the mayor of San Jose blamed Donald Trump for the violence. In the 21st century, in a democratic republic where “the people rule,” what is going on? I had my come-to-Jesus moment about this when a liberal friend told me a few years ago that she had always wanted to get into activism. Then, while auditing philosophy courses at the University of Washington in Seattle, I heard two young women on two different occasions testified that politics, for them,...