For want of a hyphen the kingdom could be lost. Countries are held together by more than a punctuation mark just as the battle in the old nursery rhyme was not fought over a horseshoe nail. But for anyone whose identity is a composite of more than one culture, usually as a result of recent migration, there is security in hyphenated nationality.

My parents were born in South Africa, and their parents were born in what was then the Russian empire. The cultural thread linking us to the old countries is Judaism, now dilute and secular. Yet I do not call myself Lithuanian-Ukrainian-South African-Jewish-British. The dash connecting past to present is something I prefer to keep on the inside. I only mention it now because there are forces at work in this election that would change not just the way we are governed, but the grammar of what it means to belong in a country.

I have had enough encounters with supporters of Scottish independence to accept that most are not driven by blood-and-soil craving for tribal segregation. The distinction they draw is between “civic” nationalism, which does not discriminate on grounds of ethnicity, and the ugly kind that produced most European wars in the 20th century. I have even heard it argued that what the SNP represents isn’t really nationalism at all but an expression of progressive solidarity that happens to be culturally Scottish: so not anti-English.

Joseph Harker: Life on a hyphen edge Read more

That is a profoundly nationalistic argument. There is ample academic research codifying nationalisms throughout history, revealing the common patterns in their genesis and the comparable myths that sustain them: the rediscovery of “lost” folk traditions; the “golden age” that came before colonisation; the need to unyoke the true spirit of the people from corrupt political establishments; and the belief that our national project is different from theirs because it flows from a spirit of inclusive optimism. I hate to disappoint the SNP exceptionalists and their fellow travellers on the English left, but the belief in the specialness of what is happening in Scotland is part of what makes it all too generic.

The genius of nationalism lies in its mobilisation for political ends of emotions that people feel as more authentic, less negotiable than ordinary politics. To tell nationalists that their party is engaged in the same power play as other parties then becomes a personal affront, a denial of their right to be an agent of destiny. It is as frustrating for the non-nationalist to argue against such faith-based politics as it is for the atheist to take on the evangelical believer. Evidence cannot penetrate the seal of conviction.

In vain do Labour candidates point out that full fiscal autonomy would exert budget pressures to make austerity even harsher for Scotland. In vain does anyone suggest that Nicola Sturgeon has an interest in seeing David Cameron continue as prime minister, because prolonging Scottish resentment at being ruled by Westminster Tories will accelerate demands for independence. Such arguments are derided as the rotten idiom of the old politics polluting the new.

Few things could be more effective in sustaining that dynamic than the current Tory campaign to strip Scottish MPs of legitimacy in the next parliament. The depiction of a Labour administration propped up by the SNP as a potential crisis for the country is, at heart, an assertion of the moral primacy of English representation in the Commons. The implication is that people who vote for a nationalist party in Scotland are voluntarily curtailing the reach of their citizenship. Their opinion on who should be prime minister no longer counts.

Thus is Scottish resentment of English dominance fed into English resentment of the Scots – what Nigel Farage describes as “taxpayers cheesed off with money going over Hadrian’s wall” and “the Scots tail wagging the English dog”. It is a potent attack. Labour candidates tell me that it is the one element of the Conservative campaign that is resonating with swing voters, far more effectively than boasts about economic recovery. That is a sad indictment of Cameron’s record: five years in government cannot make the case, so his prospects of carrying on have to be sustained by provoking a vicious cycle of cross-border nationalist enmity that will, if unchecked, split the country.

The right not to have to choose sides is a right that nationalism always eventually denies

If Cameron does stay in Downing Street, he must call a referendum on Britain’s membership of the EU, plunging us even deeper into the turbulent waters of identity politics. I once thought that a vote on Europe was necessary to settle the matter. But it wouldn’t settle anything, as Scotland’s experience proves. Now the prospect fills me with alarm at the violence that will surely be done to rational debate in the name of some mythic national emancipation from continental rule.

I feel lucky to have grown up in a country where national identity is a private concern, a fluid mass of overlapping cultural attachments – some historical, some geographical – that have never needed disaggregation. Politics has not yet forced me to rank my allegiances or jettison any as a test of loyalty. I opposed Scottish independence for many reasons, but prominent among them was sympathy with Anglo-Scottish friends and family for whom that little hyphen is more than just a punctuation mark.

It represents the right not to have to choose sides – a right that nationalism always eventually denies. English nationalism has the potential to inflict that choice on many more people, and is all the more dangerous as a result. I might forgive Cameron if I thought he didn’t understand this. It frightens me that he doesn’t seem to care.