'I'm swithering." It's the remark I've heard most often during my current tour of Scotland promoting our Road to Referendum book.

Outside book festivals, that is. At book festivals and other cultural events in Scotland just about everyone seems to be saying Yes, often preceded by the qualifying phrase "I'm not a Nationalist but ... " If you were to take the literary world as a guide, I would say it's now a slam dunk for independence. But of course they aren't the ones who will decide the referendum.

This is a completely unscientific assessment of the state of Scottish opinion, of course, based on the people I have bumped into on the road from Glasgow to Stornoway. So far I would say the Yes campaign has some way to go before it wins over the country. However, things are finely balanced and it does have moral momentum. The key is the S word.

Most of the switherers are No voters, but they evidently feel uneasy talking about saying why, and not just to me. No-one likes to say that they are voting No because they are afraid. But many still are. Our Herald opinion poll yesterday very much accords with this picture, showing 52% of Scots think the No campaign is negative, even though most still intend to vote No. Many people don't like the message they are hearing from the Unionist camp, and there is a deal of resentment at the character of the Better Together campaign. But most don't yet feel able to dismiss the scares about the pound and Europe as baseless.

The Yes side tend to be seen as the good guys, even if they look like losing. This is because they are optimistic, positive, patriotic, social. They may be naive, misguided even, but they seem to at least hope that a better Scotland is possible. There is indeed something of the evangelical tradition about the Yes campaign, with its talk of "conversion by conversation", as Yes campaign organiser Stephen Noon puts it. Independence is a faith-based project many people would love to believe in, but many still fear what they see as the cold reality of isolation.

Better Together have elected to be the bad guys: the Nay-sayers, cold-water-pourers; snatching the pound, making threats and warnings, reminding Scots of their place and the unwisdom of getting above it. This has a lot to do with the No campaign being closely identified with the most unpopular politician in Scotland: the Chancellor George Osborne.

Leaving the fate of the Union in his hands was one of the great own goals of the referendum campaign. He has acquired an almost mythic quality,

a kind of Margaret Thatcher redux. David Cameron, who comes north tomorrow to spread the word that the British economy is on the mend, does not attract the same rancour. But the mediator is the message and the Tories are still breathtakingly unpopular in Scotland.

Of course, the nominal leader of Better Together is Alistair Darling, but he hasn't a great deal of charisma and also speaks with the scolding, hectoring tones of the UK Treasury.

It is hard not to regard Mr Darling as something like a factor on a Highland estate owned by an absentee landlord.

He may be the one who orders you around but he isn't the real boss. Mind you, Scots learned to live in fear of the factor, especially in the Highlands. But it doesn't exactly build love for the Union, or Westminster, and the fact that the Tories seem now on their way back in the UK could be disastrous for Better Together. Ukip, too, is regarded by most people I speak to as a kind of unruly adjunct to the Conservative Party. Nigel Farage is an investment banker, after all. I haven't come across much anti-Europeanism, still less any concern about immigration. Scotland has had mass immigration from England over the last 20 years, but the incomers have mostly integrated well and there is far less friction here than 20 years ago. In Stornoway, where I am writing this, the problem is migration away from the islands, not EU migrants flooding over the Border.

But is being on the side of the good guys a good place for the Yes campaign to be? The polls are narrowing but they are still way behind in most of them. Would they not be better to start deploying their own version of Project Fear - how Scotland will fall off the map if it votes No, just as in the 1980s? I think not. The Yes campaign has not been very effective in conventional political terms, but it has had a very significant success among opinion formers. And this is largely because they have offered a positive prospectus that seems more aspirational.

Take William McIlvanney, arguably Scotland's most respected living novelist, who announced at Ullapool Book Festival that he will be voting Yes. The son of a miner, Mr McIlvanney has been Labour to his boots since he acquired the capacity of speech.

He was prominent in the home rule campaigns in the 1990s, making that celebrated bus-top address during the 1992 European Council meeting in Edinburgh. He says he feels Labour is now "a shop window - there's nothing in the back". He certainly hasn't lost his faith in Labour politics. He just sees no way in which it can happen under the present constitutional arrangements.

Better Together say people like Mr McIlvanney and Canon Kenyan Wright, father of the Scottish Constitutional Convention who also said at the weekend that he would be voting Yes, are part of generation past-it. Who knows them? Who cares what they say? Well, until we hear figures of comparable stature declaring for No, I think these voices do matter. And Irvine Welsh, David Greig and Ricky Ross have from very different backgrounds argued that Yes is Scotland's only option. People don't feel ashamed to say they are voting for independence. They feel they are on the moral high ground.

Richard Holloway, author, broadcaster, former Bishop of Edinburgh and probably the most respected figure in Scottish civil society, agrees. He has been depressed by the moral bankruptcy of the No campaign: the scares about the pound and being thrown out of Europe, endlessly recycled as if Scots were born yesterday. But the main reason is that he feels disenfranchised being a supporter of devo max faced with a binary choice of unacceptable opposites. Significantly, he sees Yes as the least unacceptable. Indeed, he sees it as the only way of achieving federalism in the UK.

Better Together can scoff at these "literary luvvies", as they call them. But they remain influential figures in Scotland, and none of them comes from the Scottish National Party ; indeed they mostly regarded themselves, until recently, as hostile to the idea of nationalism. Scotland is wholly engaged now in the referendum campaign. Everyone is talking about it. It has gripped the imagination in a way even the 1997 referendum campaign never did. The stakes are so much higher; the issues so much more serious. Scots are looking hard at the campaigns and wondering why the Union seems to be lacking in significant friends. Swithering Scotland may yet swither to Yes.