We are in the grip of old habits. We assume, most of us, that when a prominent political figure is assassinated, the motive for the killing is political. So it was with Charlie Kirk’s assassin. Before anything was known about the killer, President Trump’s allies and outliers decided that it was a symptom of the murderous violence of soi-disant antifascists on the left. When it emerged, subsequently, that our man was from a republican family and that he potentially may have been part of the white supremacist ‘groyper’ movement, anti-Trump types chalked it up to the violence of the Right....