With so much unemployment about, and more to come, it seems reasonable to fear that more crime will come with it. The devil, after all, finds work for idle hands, and that English proverb finds echoes everywhere. The French and the Finns say that “idleness is the mother of all vices” (the Italians think the same, except that it’s the father); the Portuguese, that “an empty head is the devil’s workshop”; the Egyptians, that “the idle hand is impure.” Who can gainsay such an accord of folk wisdom?

The U.S. crime statistics, for one. The big rise in U.S. unemployment (it’s going down a little now, but it’s still high, at around nine percent) hasn’t been accompanied by a surge in crime. The stagnation of working- and middle-class incomes hasn’t sent the sufferers out onto the street in orgies of thieving or robbery with assault. Although Americans – bamboozled by super-violent films and TV’s concentration on murder and rape – fear crime as much, if not more, than ever, still the real decline in most crimes is large, and has continued.

The reasons for rises and falls in crime are always contested, but one reason commonly cited – though not universally agreed upon – is the high rate of incarceration in the U.S. And it’s not just that the U.S. locks up people more willingly than other countries – the UK sends about the same percentage to prison. It’s that the prisoners spend longer, often much longer, inside. Research by Steven Levitt and William Spelman points to these sentences as reducing crime by a lot – about one-quarter. Other researchers say it’s much less (though still accounting for a measurable decline) and that the social effects, especially on young black men without college degrees or even high school diplomas, who are disproportionately incarcerated, outweigh the gains.

There are other reasons. Less cocaine is now taken, either heavily or recreationally, than was the case a decade or more ago. Police methods, especially forensics, have become much more sophisticated, which has meant more arrests and more convictions. People look after their property better. It may even be the case that reduced levels of lead in young bloodstreams – down by four-fifths in the past decade – have reduced crime, as high levels of lead in teenage bloodstreams have long been linked to aggression and criminal behavior.

Much more speculatively, it could be that our culture has changed. James Q. Wilson – the social scientist whose work on policing of crime-ridden areas inspired shifts to no-tolerance methods, where actions that makes neighborhoods unsafe or just unpleasant (broken windows, graffiti) are pursued and punished – said in his 2011 Manhattan Lecture that we have moved from a 1960s-inspired, ultra-liberal ethos of self-expression to a more conservative ethic of self-control. He added, though, that no one knew how to measure the effects of such a move, if move it was.