Over the past few weeks several people have told me, in complete seriousness, that they will quit Scotland and move to England in the event of a Yes vote in September.

The first time I was told this I was amazed and saddened. The second time I was merely surprised; now I'm becoming quite blasé. But I cannot understand why these people - all Scottish, all sensible and all, how can I put it gently, mature - have reached this momentous decision.

I'm very much on the Yes side of the argument but I quickly realised that there would be no point in objecting, or trying to persuade them to rethink. The decision had been taken for emotive reasons. That does not mean to say that for the people concerned, it's irrational; but I think it is fair to say that it's a decision of the heart, not the head.

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This points to something wrong in the current debate. Obviously many technical matters - not least the whys and wherefores of currency union - are crucial. Yet if the debate is just about technical detail, however crucial, it will have failed. Whether we like it or not, and I don't particularly like it, the decision that will be made in September will be essentially emotional.

For me the most emotional point of all is that people all over the world, dead and alive, would have loved to achieve independence for their country by doing something as straightforward - and, importantly, as peaceful - as recording their vote in a polling booth. It is a colossal opportunity given to very few in the course of history and I sincerely believe that future generations will be astounded if the Scottish people throw it away. But that's emotion, and as I say, emotion isn't always rational.

Paradoxically I also believe that in the final months of the campaign it will be disastrous if the language used by the politicians becomes overtly emotive. This is why I worried about Alistair Darling's remarks early in the New Year, when he suggested that Scots should be shivering with fear about the consequences of independence. This struck precisely the wrong tone.

Indeed I felt that such language might - whether intentionally or not - set off an aggressive, truculent response on the other side and that is the last thing we need.

So what should people like me, convinced Yes voters, say to decent Scots who would quit their country rather than face the realities of independence? Of course you could turn it into a joke, noting that it represents an entrepreneurial opportunity: a propitious time for removal firms and estate agents south of the Border and their like.

I have no idea of whether the few people I'm talking about are a tiny minority or represent a larger tendency. And of course there may well be many reverse journeys, made by exiled Scots who are already raring to come home to their newly independent nation.

The underlying reality in all this is that nobody knows precisely what an independent Scotland will be like. Of course there are worries, and I admit that some of them may be valid, about financial and security matters.

Anyone who claims that there is zero risk in independence is not to be trusted. And not everything will be within the control of us Scots and those we elect to govern us. This is, increasingly, a world of interdependency.

Nonetheless, when it comes to the emotive matter of what an independent Scotland will be like, the resolution is straightforward. It can and will be a better place, in so many ways, if we choose to make it such. That's emotional, but it's at the heart of the matter. It's a matter of belief and trust.

Early in Sunset Song Lewis Grassic Gibbon describes how his heroine Chris Guthrie, who symbolises Scotland, felt there were two Chrisses, fighting for her heart and tormenting her. One was essentially Scottish, the other essentially English. That was the choice then, and it's the choice now.