The debate about multiculturalism is hotting up. It also clearly splits the coalition, as the contrasting speeches of David Cameron and Nick Clegg have shown.

In all the fevered comment, the assumption seems to be that British culture should be counterposed with other alien cultures, which are problematically separate from, and should be assimilated into, it. Unfortunately for this assumption, it is a truism of anthropology that cultures vary as much within themselves as between each other. Very few are homogenous.

Imagine Steve, a white English man who can trace his ancestry back to the Norman conquest, who owns a small business, is a Tory, has children, lives in the countryside, loves cricket and is a practising Christian. Who does he have more in common with? Yousef, a Pakistan-born man who owns a small business, is a Tory, has children, loves cricket, lives in the countryside and is a practising Muslim? Or Katie, a female Welsh factory worker with no children, who hates all forms of competitive sport, is an atheist city-dweller and a member of the Socialist Workers party? If culture means shared values, then Steve has far more in common with Yousef than with Katie.

This is why attempts to define "British values" – such as those made by David Cameron and Gordon Brown before him – failed, and why they will always fail. For their definitions are inevitably either so narrow as to exclude people who even by the most restricted definitions are British, or so broad as to include people who by even the most extensive reckoning are not. That is why the far right seeks to define cultures not in terms of values, as mainstream politicians do, but in terms of skin colour and race.

For others, the issue is behaviour. Meaning, to bring it to a point, that some Muslims have tied bombs to themselves and murdered huge numbers of people, including the 52 killed in London on 7/7. This, more than anything else, pointed to the failure of multiculturalism. But there is a two-fold problem in such an analysis. First, some who are by restricted definitions part of traditional British culture also perpetrate violent crimes for political reasons (for example, some animal rights activists or, presumably, those currently targeting Celtic football club). Secondly, Muslims who commit such crimes are outliers – there are, after all, perhaps 2.8 million Muslims in the UK, of whom vanishingly few have been convicted or even suspected of terrorism. If there was – which there never has been – a homogenous "British culture", it would still have its share of extremists or fanatics who would do terrible things.

Of course the incoherent linkage of multiculturalism with violence is not the real issue. The IRA bombing campaigns of the 1970s and 1980s, which far exceeded the efforts of the radical Islamists, did not call forth anything like the reaction to 7/7. Linking multiculturalism with violence is a code to make acceptable a much wider attempt to represent it as a problem. Central to this is the way popular discourse has imagined that the British, white working class has somehow been discriminated against in terms of access to jobs, housing and public services. It is a nonsense, of course – and whenever examples are put forward, they almost invariably turn out to be untrue and to conflate issues of disadvantage with those of culture and race.

There is a wholly dishonest inversion in which ethnic minorities are represented as having "special privileges" while the indigenous population are the "discriminated against victims", forgetting the primary inequality between rich and poor in favour of an imagined cultural (or, for the far right, racial) war among the poor. Interestingly, this faux-victimhood rarely comes from the traditional working class itself, who largely know better. It comes from the Poujadistes, who have always formed the bedrock of monoculturalist sentiment, insisting that they alone are "decent, right-thinking people". Note that I am talking here specifically about the concept of preferential access to jobs and services, as opposed to the perennial debate about the impact of immigration on wages and unemployment. The latter is not an issue of multiculturalism per se, since it could arise regardless of the cultural background of the immigrants.

The bigger political issue here is that of globalisation. The supposed advantages and inevitability of economic globalisation have been insisted upon for decades, and voted for by many of those who now rail most loudly against its effects. For, strangely, its proponents seem to imagine it as no more than a globalisation of capital, not working forces. They also see those who oppose said globalisation as crazy leftists. But when confronted with the globalisation of labour, they shriek about multiculturalism as the creation of, well, crazy leftists, and make common cause with the racial supremacists whom they otherwise abjure. As a consequence, multiculturalism in its commonly understood sense is depicted as the creature of some mythical liberal elite (who hang out with the equally shadowy PC and Human Rights brigades) rather than being primarily the legacy of colonialism and the consequence of neoliberal economic policies, including those pursued by the EU.

As it stands, the multiculturalism debate is a proxy for everything other than culture: race, inequality, markets, globalisation, terrorism – perhaps modernity itself. But certainly not culture – because all cultures are multicultures, and cannot be anything else.