In the 1990s, John DiIulio, a conservative American academic, argued that a new breed of "superpredators" — "kids that have absolutely no respect for human life and no sense of the future" — would terrorize Americans almost indefinitely. He was not alone. Experts were convinced that crime would keep rising.
DiIulio later recanted, and it is clear the pessimists were wrong. Even as he wrote, America's crime wave was breaking. Its cities have become vastly safer, and the rest of the developed world has followed.
From Japan to Estonia, property and people are now safer than at almost any time since the 1970s.
Confounding expectations, the recession has not interrupted the downward trend. Even as America furiously debates the shooting of Trayvon Martin, new data show that the homicide rate for young Americans is at a 30-year low.
Some crimes have all but died out. Last year there were just 69 armed robberies of banks, building societies and post offices in England and Wales, compared with 500 a year in the 1990s.
In 1990, some 147,000 cars were stolen in New York. Last year, fewer than 10,000 were.
Cherished social theories have been discarded. Conservatives who insisted that the decline of the traditional nuclear family and growing ethnic diversity would unleash an unstoppable crime wave have been proved wrong. Young people are increasingly likely to have been brought up by one parent and to have played a lot of computer games. Yet they are far better behaved than previous generations.
Left-wingers who argued that crime could never be curbed unless inequality was reduced look just as silly.