WHEN the American expert on the Today programme spoke of a "cognitive chute", Alice and that weird rabbit hole sprang to mind.

Professor Robert Cialdini, emeritus professor of psychology ("and marketing") at Arizona State, was purporting to talk about clarity of language. "Cognitive chute" was his best shot.

Prof Cialdini had been called in to answer the question of the question. You know the one: "Do you agree that Scotland should be an independent country?" Alex Salmond wants to make the inquiry in 2014. A lot of people – the professor, a former Chancellor, purveyors of opinion polls – think he has no right.

They prefer the view from Arizona State: the proposed question is "loaded and biased". It sends the suckers down the fearsome chute "designed to locate agreements rather than disagreements". It is, in short, a trick question.

Put aside the scientific basis for the existence of the professor's perceptual helter skelter. If it exists, all propaganda works all of the time: correct? Instead, make a simple demand of our national focus group. Thus: hands up anyone who truly doesn't understand the question.

In the editorial handling of news stories, one basic task is to establish how few words are needed to convey information. So how would a good, dispassionate sub-editor fare with Mr Salmond's question? Tellingly, it seems to me, his Unionist opponents want to add words – "Do you agree or disagree"; "approve or disapprove" – rather than reach the essence of the argument.

They also seem to think that likely voters are stupid. Why else worry about manipulation? It only matters if, after all this time, the Scottish electorate still doesn't grasp the argument. The fact that the same objectors are hell-bent on preventing anyone disinclined to answer Yes or No from having a say is, of course, revealing.

Alistair Darling, the former Chancellor, also reckons the question is biased. Lord Forsyth, former beloved Secretary of State for Scotland, asserts that "We have a rigged question, a rigged role for the regulator, a rigged expenses system and, on top of that, the question that there should be a rigged franchise." I am moved to quote the Prime Minister: calm down, dear.

The issue of bias only arises if voters are capable of being deceived. The question as proposed, I submit, involves no such risk. This is as clear and simple as it gets within the fatuous – dare I say rigged? – arguments over the meaning of the Scotland Act with regard to the constitution.

I have a question of my own: is this the best Unionists have got? At every turn, we are promised a serious debate. With each passing day we are told that someone is just about to make a "positive case" for the continuation of the United Kingdom. Instead, the likes of Michael Forsyth – let's pick on him – counts as a representative voice.

He is not alone. George Osborne, the present Chancellor, has claimed that we would no longer be allowed to use his currency and would be forced to join the euro. Others around him have said, confusingly, that we wouldn't be allowed to remain in the European Union in any case. Lord Ashdown has raised the spectre of Kosovo; Jeremy Paxman – it's the way he tells them – of blood-soaked Mugabe.

You wouldn't be able to watch the BBC. You wouldn't have a health service. Inward investment would collapse. Scotland would drown in debt. Scotland would be defenceless. Scotland would be at the mercy of the Bank of England. At First Minister's questions this week, Johann Lamont argued that talk of independence was causing ordinary Scots to worry over their mortgages, savings and pensions. Presumably she meant those who are not already deeply worried.

But let's say, just for the purposes of argument, that all of this is true, even the parts that touch the borders of fantasy. How does any of it amount to advocacy, a positive case, for the UK? Who is there explaining what Burns called "the boasted advantages which my country reaps from the Union"?

Thus far, Unionism has come up with a weird mixture of Private Frazer ("Wir doomed!") and the agonised Walter Scott of the first Malachi Malagrowther letter: "We had better remain in union with England, even at the risk of becoming a subordinate species of Northumberland, as far as national consequence is concerned, than remedy ourselves by even hinting the possibility of a rupture".

The case begins, presumably, with a basic assertion: three centuries of Union have been good for Scotland. It then hits its first obstacle: if that's true, why can't Scotland afford independence? The Unionist might then reply: precious few of your grandparents wanted to break up Britain. Why was that?

The point is fair enough. Nationalism as a mass movement is of recent origin. It made little headway during most of the 20th century, even when large bits were dropping off Britain's empire. Scotland generally did not pause to think about self-government or colonialism: apparently, those didn't apply to us. Nationalism was a slow journey. It picked up pace – coincidentally or consequentially – as Britain became steadily less impressive.

In recent years Westminster politicians have tried several times to reintroduce Scotland to the virtues of "Britishness". It didn't work. But was that because Gordon Brown and others besides failed to explain themselves, or because the arguments failed to convince? I only say that it was a bit of a stretch to claim, as they did, that notions of tolerance and fair play are somehow uniquely British.

What could a Unionist say if spreading despondency palls? Ironically, it's pretty much what a honest Nationalist would say. It's at the heart of all of Alex Salmond's talk about "social Union", and things preserved. The reality is that in gaining independence some things will be lost. Therein lies the choice.

Like it or not, Britain still counts for something. It has, even yet, a standing in the world that Scotland could not achieve. You can see it – mock it, if you like – in international affairs. You can see it – deplore it, if you like – in the City of London's role within global finance. You can detect it within the business of the UN or, even yet, the EU. It underpins Britain's client relationship with America.

For a Nationalist, these are things we'd be well rid of. That's not exactly the point. Modern Britain is the legacy of an imperial past, but the legacy has not disappeared entirely. Britain has ties – cultural, economic and political – that still span the globe. Scotland has family instead. You might well prefer that alternative. But independence means you could no longer have both.

Britain's intellectual heritage alone is no small thing. The great Scots – Hume, Scott, Stevenson, Adam Smith – all knew it. Whether the great English edifice of language and thought was to Scotland's advantage as native talent drifted south is another matter. The relationship existed. Britain was English-dominated; it was not merely an English creation.

Unionists fail to articulate that fact, perhaps because they don't bother to try. Perhaps they don't bother to try because all such claims speak always of the past, of what was. Their real task is to explain why Scotland would have a better future within the United Kingdom. It seems – and make of this what you like – to be beyond them.