Independence could rob us of our sense of nationality

Few of us will be doing the equivalent today to mark England's patron saint's day, possibly because it isn't clear what the equivalent would be. If it were authentically to reflect modern English culture, it would be shaving your head, sporting a selection of tattoos and a football shirt crafted from pure polyester, and downing a dozen pints of the national drink, which seems to be Stella Artois or Smirnoff Ice.

This is a less edifying depiction of our neighbours than Shakespeare's Henry V before Harfleur, urging his men to cry "God for Harry! England and St George!" But then, it has always been tricky to pin down what is characteristically English. One magazine competition looking for a definition was won by someone who wrote: "Being English means not worrying too much about what it means to be English."

Being Scottish (or Welsh, or Irish) is a more straightforward proposition in at least one particular, because part of one's national identity can always be described by what distinguishes it from being English. During my lifetime, Scots have certainly become more and more inclined to stress these differences, but even the staunchest Unionist would regard himself as Scottish and British, or English and British.

Very few people, surely, describe themselves as British tout court, without a primary allegiance to one of the home nations – though, of course, an awful lot of English people would say that they were "half Scottish" or "half Welsh". And I suspect this was true even at the height of Empire; writers such as Carlyle and Buchan might not have objected (as most modern Scots certainly would) if they were called Englishmen, but their Scottishness is solidly to the fore in their work and character.

The two writers principally responsible for describing (and if it comes to that, inventing) many of the fundamental aspects of Scotland – Robert Burns and Walter Scott – were both, as it happens, convinced Unionists. But as they went about forging the national identity, they did not ignore the ambiguities generated by being Scottish and British. Indeed, the poet Hugh MacDiarmid – a Nationalist – identified duality (his less than snappy "Caledonian antisyzygy") as a primary characteristic of his countrymen, and it is the theme of two of the greatest books produced by Scots: James Hogg's Confessions of a Justified Sinner and Robert Louis Stevenson's Dr Jekyll and Mr Hyde.

Despite the political success of the SNP over the past two decades, what will determine the outcome of the referendum on independence, I suspect, will be how people think about these identities, rather than the financial pros and cons of abandoning the Union.

Those matter, naturally, and the SNP's relative competence in government means that the idea of an independent Scotland is not, as it would have seemed in my childhood, a fairy story. Those defending the Union would be wise not to argue that such a thing is impossible, or that some Greek-style financial disaster would be bound to follow. Even if we would be worse off after separation, it is clearly not unthinkable (and there's no quicker way of getting someone's back up than by suggesting they can't do something because of their own shortcomings and deficiencies).

The narratives which matter are not to be found in the pages of the GERS report, but in the stories of people's everyday lives, and in family histories. Most families will have relatives who have moved to other parts of the UK, and there is no straightforward way of labelling many people's nationality (other than what they think of themselves as). Two 18-year-olds, both born and brought up in England, but with three Scottish grandparents, and now studying or working north of the Border, may give different answers when asked whether they are Scottish or English.

It is worth remembering that independence is not, for those who oppose it, a step into "the early days of a better nation", but the forcible removal of their existing nationality. One doesn't need to scaremonger about border controls or freedom of movement within the UK – though possible, it doesn't seem very likely in the immediate future – to point out that people will lose something if the Union ends. Convinced Nationalists will be glad to be shot of it, of course, but there will be very many people who will feel that they have been robbed of their chosen nationality.

Scots living in England will have to decide, for example, whether to apply for a Scottish passport or not. English people with Scottish ancestry will have part of their inheritance rendered foreign. And neither group will have a say in the matter.

It is natural for the SNP to paint independence as an opportunity, and canny to characterise all opposition as timidity. But as things stand, it is the opponents of independence who have the choice to define their nationality; they can be Scottish and British, each to the degree they feel, or choose. They can attend Burns suppers and choose between St Andrew and St George. It is the status quo which is flexible; independence is not a liberation, but a restriction of the options.

It was the period when the Union was strongest which saw the construction of many of the central components of "Scottishness" by Burns and Scott. It would be a poor excuse for a person who did not regard the stories they present as more important in shaping his identity than where an independent Scotland would figure in the OECD tables. But the rest of these islands have a story, too, and to break up the Union is to write ourselves out of that narrative. Burns thought it would be "insanity to abandon [that] for untried visionary theory". No doubt Alex Salmond would think him insufficiently patriotic.