Perhaps no one helped bring violence and the disruption of all norms into the mainstream from the fringes more than Saul Alinsky. His book Rules for Radicals explains what we are seeing today and how we got here. Just as the title of this 1971 work of practical militancy suggests, it codified tactics intended to overturn the constitutional order. At the same time, the “rules” Alinsky had championed threatened — and promised — to propel American politics ineluctably into violence. The most reprehensible accomplishment of Rules for Radicals was convincing a generation of progressive Democrats that it no longer needed...