Whether amid fascist regimes, the academy, wannabe intellectuals, and cultural gatekeepers, Williamson argues, things escalate quickly: “leaders invent, hype, or exaggerate an out-group threat, make appeals to in-group solidarity, and, empowered by the purported emergency they have manufactured, set about on a course of sundry illiberal and authoritarian actions aimed not at persuasion or argument but at suppression, removing the out-group enemy from the public square, cutting them off from the realm of ordinary democratic discourse.”

But in addition to the ochlocrats’ propaganda, mob members find themselves strongly, if peculiarly, drawn to their bad behavior by an insatiable need for belonging. “The in-group dissolves the individual identity,” Williamson posits, “relieving the stressed and anxious pleb of an identity that was more a burden to him than an asset; at the same time, it provides a new and larger sense of identity as a member of the in-group. To join a mob is simultaneously an act of self-abasement and self-aggrandizement.”

And of course the culture and technology of contemporary interaction act as powerful accelerants to the already-raging fire of mob rule. Williamson cites studies of online behavior showing decisively that “both interactions with like-minded people and interactions with people holding other viewpoints tend to reinforce the preexisting views of those in the conversation and to exaggerate them. For that reason, the structure of social media makes outraged polarization practically inevitable.”