It is essential for those in power in Britain that the riots now sweeping the country can have no cause beyond feral wickedness. This is nothing but "criminality, pure and simple", David Cameron declared after cutting short his holiday in Tuscany. The London Mayor and fellow former Bullingdon Club member Boris Johnson, heckled by hostile Londoners in Clapham Junction, warned that rioters must stop hearing "economic and sociological justifications" (though who was offering them he never explained) for what they were doing.

When his predecessor Ken Livingstone linked the riots to the impact of public spending cuts, it was almost as if he'd torched a building himself. The Daily Mail thundered that blaming cuts was "immoral and cynical", echoed by a string of armchair riot control enthusiasts. There was nothing to explain, they've insisted, and the only response should be plastic bullets, water cannon and troops on the streets.

We'll hear a lot more of that when parliament meets - and it's not hard to see why. If these riots have no social or political causes, then clearly no one in authority can be held responsible. What's more, with many people terrified by the mayhem and angry at the failure of the police to halt its spread, it offers the government a chance to get back on the front foot and regain its seriously damaged credibility as a force for social order.

But it's also a nonsensical position. If this week's eruption is an expression of pure criminality and has nothing to do with police herassment or youth unemployment or rampant inequality or deepening economic crisis, why is it happening now and not a decado ago? The criminal classes, as the Victorians branded those at the margins of society, are always with us, after all. And if it has no connection with Britain's savage social divide and ghettoes of deprivation, why did it kick off in Haringey and not Henley? [...]

This time, the milti-ethnic unrest has spread far further and faster. It's been less politicised and there's been far more looting, to the point where in many areas grabbing "free stuff" has been the main action. But there's no mystery as to where the upheavel came from. It was triggered by the police killing a young black man in a country where black people are 26 times more likely.