Owen Jones's indignant, well-argued debut begins with a joke: "It's sad that Woolworth's is closing. Where will all the chavs buy their Christmas presents?" This was uttered by the host of a dinner party attended by the author in "a gentrified part of east London", at which liberal views are taken as a given and, though everyone present has a professional job, not everyone is white, male or straight.

Jones, who is in his late 20s and has worked both as a trade-union lobbyist and as a parliamentary researcher for a Labour MP, doesn't say how he reacted to this mindless put-down at the time. Did he refuse to eat the blackcurrant cheesecake that was being "carefully sliced" as his host sought to fill an awkward silence? Did he storm out and call time on their friendship? Whatever he did on the night, its casual malice led him, indirectly, to write this book, which argues that class hatred is the last acceptable prejudice.

Chavs is packed full of good reporting and useful information. Jones singles out for opprobrium middle-class contempt towards working-class people, those regarded by rightwing commentators such as Simon Heffer as the "feral underclass". In this caricature, peddled by spittle-flecked websites such as chavscum.co.uk and tacitly endorsed by the mass media, "chav" means "underclass", which means working-class people who don't keep their noses clean or behave impeccably. The word's etymology is contested: some accounts associate its origin with chavi, a Romany word for "child" or "youth", which developed into "charva" – meaning scallywag – used for a long time in the northeast. Others treat it as an acronym for "Council Housed and Violent". Its wider use took off about 10 years ago. In early 2004 I worked briefly for a tabloid newspaper whose offices rang with its daily use (along with its bedmate, "pikey"), directed not towards the paper's readers, but towards those it was assumed would be too "thick" to read any newspaper at all. Chavs, Jones writes, are unremittingly portrayed as "Thick. Violent. Criminal." Travel brochures still apparently promise "Chav-Free Activity Holidays", while the London fitness chain Gymbox has felt free to advertise classes in "Chav Fighting".

Jones digs beneath this foul new orthodoxy to reiterate the facts of increasing inequality, which has led British society to become ever more segregated by class, income and neighbourhood. In such circumstances, miscommunication has deepened between the classes; the Conservatives' demeaning of trade unions has helped to strip the working classes of what public voice they had, so that the middle class has effectively become the new decision-making class.

But while it's always right to argue, and to keep arguing, that the balance of power in our social and economic structure is hopelessly, immorally off-whack, there is a cost to denying the personal volition of working-class individuals. Jones – understandably given the book's subtitle – treats class hatred as a one-way street, rather than a collusive, often subtle, process which demeans everyone. In fact, a great deal of chav-bashing goes on within working-class neighbourhoods, partly because of the age-old divide between those who aim for "respectability" and those who disdain it. Inverse snobbery can also be expressed towards those perceived to be "stuck-up". New Labour pummelled liberal critics with populist arguments that ran along this pre-existing faultline. Both Jack Straw and David Blunkett, with seats in Labour's post-industrial "heartlands", tried to out-Asbo each other during their respective terms as home secretary. Middle-class hatred of working-class people – or, rather, a particular image of working-class people which some hold in their minds – is a different beast, saying more about the way in which the education system, especially, is structured to prevent most privileged students from ever having to confront their own averageness.

The one occasion on which the agency of an individual is properly invoked by Jones is in his discussion of the case of Shannon Matthews, the Dewsbury schoolgirl whose mother, Karen, conspired to have her kidnapped in the hope of netting a £50,000 police reward. In that case, Karen Matthews is rightly considered to represent only herself, rather than her wider, poor working-class community, on which the newspaper stories fixated. Yet a similarly detailed chapter on spurious links made in the mass media between support for the BNP and "white working-class culture" makes no such distinction. Jones claims that "hundreds of thousands of working-class people" were "driven into the waiting arms of the BNP" before the party's electoral collapse in 2010, but he fails properly to establish the link between being working class and holding far-right views. He adds fuel to the fire by adding: "Karl Marx once described religion as 'the sigh of the oppressed creature': something similar could be said about the rise of the far right today." Quite apart from the questionable nature of equating religious faith with fascist sympathies, the quote points to a difficult truth about left-of-Labour politics: it requires working-class people to be "oppressed creatures", always victims, not rational actors in a play they help to write.

Divide-and-rule political gambits don't work unless there are enough people who don't already tend, in some way, to one side or the other: classes are complicated entities. One example of this is how different people living in council housing reacted in 1980 to the introduction of the "right to buy" policy, which, Jones argues, was calculated to undermine working-class solidarity. Their decisions were partly a reflection of the circumstances they were in, and partly a reflection of their broader outlook as individuals. Some people thought the idea of owning their own home was wonderful, or held it as a long-term aspiration. Others found the idea repellent and saw it as a deliberate attempt to break up communities. Still others were concerned only with the practical elements – could we afford to replace our own boiler?

Jones doesn't acknowledge this, preferring to treat "the working class" as a single political bloc. Because of this tendency, it can feel as though he romanticises an ideal of working-class life which doesn't always hold true. There is a tinge of the noble savage here and there, particularly in the over-careful way he presents and interprets quotes by his working-class interviewees. Despite this fault, Chavs makes an important contribution to a revivified debate about class.

Lynsey Hanley's Estates: An Intimate History is published by Granta.