Welcome to the 1970s! In New York, anyway, one of the decades Tom Wolfe denominated "purple" has made a stunning comeback. Consider crime. After a precipitous decline that began under the mayoralty of Rudy Giuliani and continued under Michael Bloomberg, violent crime has soared in the city. From May 2014 to the end of May this year, shootings increased almost 10 per cent while murders jumped a stunning 19.5 per cent during the same period. Meanwhile, Central Park has once again become a haven for thieves and muggers. "Police are investigating another mugging in Central Park," begins a May 20 story in the New York Post, "the latest in a string of robberies that has residents on edge."

The centrepiece of Bill de Blasio's mayoral campaign in 2013 was a promise to end one of the most effective weapons against violent crime: "stop and frisk", the practice by the police of stopping, questioning and, in some cases, frisking suspicious characters. De Blasio wanted to end the practice because the overwhelming majority of those stopped and frisked were Black. The reason for this was that the overwhelming majority of suspicious characters that the police encountered were Black, but that reality did not prevent de Blasio from pretending that the practice was inexcusably racist. Former Police Commissioner Ray Kelly warned that "people would suffer" if the prophylactic practice was abandoned. No matter. It was too good an opportunity for a left-wing demagogue to ignore.