Where to begin with David Starkey? Having spoken to friends and seen the response on Twitter, it's clear that many were left speechless at his racially inflammatory tirade on Newsnight. I can more than empathise: it was one of those moments when what is said so extreme, it is initially difficult to compute.
Let's be clear: what David Starkey said was not just offensive, it was downright dangerous. His initial suggestion that Enoch Powell had been vindicated -- "The Tiber did not foam with blood but flames lambent, they wrapped around Tottenham and wrapped around Clapham" - would, in isolation, be outrageous enough.
Powell predicted that mass immigration would bring turmoil to Britain's streets. It was a prophecy that proved unfounded. We are far less racist a society than we were in the 1950s, when a large majority objected to interracial relationships. But Starkey knew there would be a newly receptive audience in the post-riot aftermath.
His championing of Powell was eclipsed by his subsequent comments. In offering an explanation for last week's violence, Starkey claimed that "the problem is that the whites have become black". His theory was that white kids had become infected by black culture, and this had led them to violence and disorder. A prominent black politician like David Lammy, on the other hand, sounded "white". For Starkey, being white meant being "respectable"; being black meant "violence".
There is strong competition for the lowest point of Starkey's rant -- but when he embarked on an impression of a "patwa" accent, I could barely believe what I was watching. It was Enoch Powell meets Alan Partridge.
Some would argue that it's not worth even engaging with such apparent bigotry, but -- uncomfortable as it may make many of us -- his arguments will have resonated with many. We have to take them on.
His point that hip-hop culture transforms white kids into gangsters was an assertion grounded in prejudice, not fact (indeed, I challenged him -- as a historian -- to justify his sweeping assertions with evidence). I grew up sharing a room with a brother who was obsessed with hip-hop. I hope he doesn't mind me saying it, but he's about as far from "gangster" as it's possible to be.
Anti-social behaviour is real, and should never be dismissed by the left. It is far more common in poorer communities. When I went to Ashington -- once the biggest mining village in the world, since devastated by the closure of the pits -- I heard a number of stories about teenage anti-social behaviour.
But the point made eloquently to me by residents was that young people, who had grown up with all the frustrations and boredom of poverty, felt they had little future to look forward to. That's a reality in communities across the country - and, though no excuse, no wonder a small number respond by making other people's lives a misery.
The Joseph Rowntree Foundation completed an extensive study into gangs: I doubt Starkey has read it. It found that there was a strong link between "territorial behaviour" and poorer communities. Gangs could provide some young people with fun, excitement and support they otherwise lacked. It "appeared for some to be a product of deprivation, a lack of opportunities and attractive activities, limited aspirations and an expression of identity", as well as a "coping mechanism" for those living in poverty.
It's nothing to do with ethnicity, in other words. It's to do with poverty.
As for riots -- well, Starkey has found an all-too-convenient way of blaming black people for riots that involved people from a whole range of ethnic backgrounds. Even if the looters weren't black, they had somehow "become" black.
Now, I'm intrigued that Starkey has such a unique in-depth knowledge of the cultural interests of those who took part in the violence. But let's deal with the facts that have emerged.
Of those who have appeared in court, the vast majority are men, aged under 24, and out of work. The riots took place in some of the poorest communities in Britain -- like Hackney and Tottenham. This was a tiny slither of Britain's burgeoning young, jobless poor: indeed, one in five young people are out of work. That isn't to justify their behaviour, any more than to state that a lack of affordable housing and good jobs has fuelled the rise of the BNP is to justify Nick Griffin's racist cabal. But, if a tiny proportion of those who feel they have no future to risk respond by rioting and looting, that is enough to bring chaos to Britain's streets.
Other commentators have looked to other explanations: Britain's hyper-consumerism, where our status has so much to do with what we possess; and a profound inequality in British society, not least in London where the richest 10 per cent are 273 times better off than the bottom 10 per cent.
Now that peace has returned to our communities, we have time to think through these explanations. But my fear is that -- with an understandable backlash underway -- Starkey's comments could prove to be a disastrous turning point. He has put race at the top of the agenda when millions are scared and angry. As some took to the streets in support of Enoch Powell's "river of blood", there will be whispers across the country "that Starkey has a point".
I did my best to challenge David Starkey in the studio -- difficult though that was. At a time of backlash and economic insecurity, we all need to be taking these arguments on in our communities. If we fail, last week's riots could be a dark foreshadow of far worse to come.
Owen Jones is author of "Chavs: The Demonization of the Working Class"