The true believers who remain are enthusiastic leftists who justify — or welcome — the dissolution of law and order.

New York City must be one of the few places on earth where chaos nostalgia is widespread. Many were the laments, in the Giuliani-Bloomberg era, that the city was “too sanitized,” “too gentrified,” “too boring,” “anodyne,” “suburban.” Often you’d hear people saying, or declaiming, that their ideal vision of the city was the 1970s–1980s one — oh, for the New York of CBGB, of Lou Reed, of the Tompkins Square Park riots. Occasionally people would sneeringly express revulsion that the sidewalks were teeming with strollers. What have we done, we’ve made this place safe enough for babies! And yet the population, which was smaller in 1990 than it was in 1940, boomed. More than a million more New Yorkers squeezed in between 1990 and 2010. It was as if a city the size of Austin grew atop the existing city.

On a return visit this weekend to the Upper West Side neighborhood where I’ve lived for more than a quarter of a century, the fear in the air was palpable. The population seemed to be reduced by about half. New Yorkers steer around each other on the sidewalks, some of them walking in the street to avoid passing near a stranger. A lady declined to ride the elevator with me and my children. People are especially terrified of the subway, whose ridership is down 80 percent from normal levels. Friday night, at a time when there would ordinarily be 50 or more people riding on any given car of the 1 train, there were about seven. Downtown was morose, grim, broken. Graffiti (the anarchists’ symbol, “ACAB” for “All Cops Are Bastards”) was much in evidence.