stop playing, you know good and well "why?"

NYTimes | Outside a London court last week, as those accused of looting and rioting in the most destructive and widespread violence in recent British history faced justice, a mother turned to her 11-year-old son, accused of theft, and asked simply, “Why?”

That question has been at the heart of a fraught national debate as Britons puzzle over what drove even some previously law-abiding people to steal, sometimes risking arrest for nothing more than bottles of water. The debate has often divided people into predictable camps.

The Conservative prime minister, David Cameron, stood up in Parliament as Britain smoldered around him on Thursday and railed against “mindless violence and thuggery.” His critics on the left blame deep mistrust of the police in poor communities, and income inequality they say will worsen as his government pursues sweeping cuts in spending and social welfare.

Some commentators have blamed modern society at large. The Daily Telegraph struck a popular chord when it blamed a “culture of greed and impunity” that it said extended to corporate boardrooms and the government itself. Many politicians, meanwhile, have lashed out at technology — including the instant messaging that encouraged looting — for whipping up the crowds.

But as more details of the crimes emerge, the picture has become infinitely more complicated, and confusing. In some of the more shocking cases, the crimes seemed to be rooted in nothing more than split-second decisions made by normally orderly people seduced by the disorder around them.

An aspiring social worker, Natasha Reid, 24, turned herself in after stealing a $500 television. Nicolas Robinson, a young engineering student who had never been in trouble with the law, grabbed bottles of water because, his lawyer said, he was thirsty.

The 11-year-old, the youngest looter arrested, stole a trash can.

At several of the riots last week, those perpetrating the violence had no ready explanation for their behavior. One young man, kicking trash cans into the street, shrugged when asked why. And the atmosphere in Hackney’s Pembury Road low-income housing projects was sometimes one of adrenaline-driven glee. Looters whooped as they stripped a convenience store bare, yards from the police.

Even some Londoners who had initially condemned the riotous behavior joined in. Bystanders had watched in shock as rioters lined up against police officers on Tottenham’s main street last weekend, setting fires and looting. The mood shifted dramatically, though, after officers moved in, dogs barking and horses charging. One man, suddenly emboldened, grabbed a box of pears from outside a convenience store. A woman carried off an armful of coconuts. Another man, seemingly conflicted, sprinted, then turned back briefly to snatch a crate of bottled water.

Clifford Stott, a social psychologist at the University of Liverpool who studies riots, says that behavior, at least, is not unusual. Bystanders, he said, often turn against the police when they themselves get swept up in a broad crackdown. “That confrontation makes them start to think that the police are wrong, not the rioters,” he said.