ROGER KIMBALL: The Purity Spiral Turns, as Courage Goes Missing.

The journalist Gavin Haynes has a great phrase for a familiar and disturbing phenomenon: the purity spiral.

“A purity spiral occurs,” he writes,  “when a community becomes fixated on implementing a single value that has no upper limit, and no single agreed interpretation. The result is a moral feeding frenzy.”

Students of history will know all about this species of perverted gustatory over-indulgence. The French Revolution is one locus classicus.

In that macabre carnival, the more extreme Montagnards consumed the (somewhat) moderate Girondists before turning to consume themselves. No citoyen, not even Robespierre himself, could be sufficiently virtuous to satisfy the inexorable demands of revolutionary zeal.

Mao’s cultural revolution provides another classic example. In the late 1960s, the Red Guards took to the street to identify and destroy anyone and anything involved with traditional Chinese culture. The result was an orgy of destruction and murder on an industrial scale.

Read the whole thing.