Nicola Sturgeon made an address to the SNP conference at the weekend and it was short and didn’t appear to say very much, but it’s worth a closer look, because it highlights a few of the problems the First Minister faces in her campaign for independence. It also underlines where, and why, Ms Sturgeon, and others in the movement, have been getting the tone and language wrong.

To summarise the 400 words or so, Ms Sturgeon said the priority of her government was tackling the health crisis, but she also said Scotland had to be ready for What Comes Next (you know where this is going, don’t you?). “Support for independence has risen,” she said. “It has become the sustained and majority view… and if we show unity of purpose, humility and hard work, I have never been so certain that we will deliver it.”

In a way, I feel sorry for whoever writes this stuff. Not only do they have to get the words “never been so certain” and “humility” in the same sentence, they also have to balance the high wires of two different audiences. They know the speech will be read by lots of non-SNP members: don’t-knows and switherers (many of whom think the pace of the independence campaign is too fast and too furious). But the speech is ostensibly written for SNP members (many of whom think the campaign isn’t fast or furious enough).

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It is partly this tension that creates many of the problems the First Minister, and others in the independence movement, face whenever they open their mouths. Ms Sturgeon said the case for independence had to be made with cool heads, patient persuasion and humility, but in the same breath she said independence has never been so certain.

You get a lot of this from independence supporters: Joanna Cherry said the other day that Scotland was on a highway to independence and will leave the UK at the next exit.

They do this for a number of reasons. First, it is aimed at assuaging the hard core of the SNP – they are impatient and fidgety, and it helps to be told that independence is – no buts, no doubts – going to happen. Second, in constantly saying independence will happen, the SNP is hoping for an illusion-of-truth effect in which a statement is repeated to the point where people start to believe it. I think this may already be having an effect on some unionists, including some high up in the Conservative Party who say in private that independence is now certain to happen.

The Herald: Mark SmithMark Smith

But there are real dangers for the SNP in all of this – in talking, and behaving, like something is certain to happen. Ms Sturgeon is probably aware of it – which may be why the word “humility” was bunged into the speech – but the politics of certainty rather than humility is still something the First Minister, and others, do with increasing frequency. There are a couple of good reasons why it’s the wrong thing to say.

First, voters can see that certainty about Scottish independence is misplaced, partly because it’s based on a misinterpretation of the data. Ms Sturgeon said in her speech that support for independence has risen and become the public’s sustained and majority view and she bases this presumably on the recent run of opinion polls. But, while there’s undoubtedly been a rise in support, there is no evidence for the First Minister’s statement that it’s the majority view. Polls showing 51-53% support for independence are based on those who express a Yes or No view – the don’t-knows are not included and one of the things we know, surely, is that the don’t-knows hold the key to the result.

Certainty about independence – in public at least – also risks running into another problem: the backlash, sometimes known as The Kinnock Effect. You probably remember it. Neil Kinnock thought Labour was certain to win the 1992 election. He held a big rally and punched the air and yelled “all right!”. and then Labour lost the election. Kinnock himself later recognised there was probably a backlash. “Instead of modest competence … we had everything but the Tredegar male voice choir singing.” It may have cost him the election.

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The same sort of problem exists for the SNP, which is why, if you listen carefully, you can hear the sound of strain and contradiction in Ms Sturgeon’s speech. Including the word “humility” is an attempt to address the contradiction; it’s probably also why she called on her party to “reach out – to all of Scotland – like never before”. But it’s not an easy problem to resolve – the First Minister is caught in the certainty and humility trap.

Perhaps the answer is for Ms Sturgeon to actually display some of the qualities she espoused in her address to the conference. She said in the speech that it’s people who live in Scotland who are best placed to harness the country’s resources, but why doesn’t she have the humility to acknowledge Scotland needs to share its decision-making with other countries (including – yikes! – England)? Even after a Yes vote, Scotland would have constitutional independence, but not independence in any total sense: our ability to be autonomous would be limited just as it is for every other nation in the world, including the UK after Brexit, and, what’s more, we would cede sovereignty for the good of the nation.

The First Minister should also try to do something else that she mentioned in her speech, and engage much more in the politics of persuasion rather than the politics of certainties (which aren’t really certainties). “An independent future lies ahead,” she said. She cannot know this: an independent future may lie ahead, it may not. It is not humble to say that you know the future.

I appreciate, of course, that the First Minister says stuff like this because she’s got that high-wire problem of addressing the two audiences – SNP members and voters in general. But that’s her problem, not ours.

To bring Scottish independence about, and avoid a backlash against her nationalist certainties, she actually has to do what she is calling on her party members to do. Persuade voters that independence is a good idea. Acknowledge the real situation that the country is divided on the subject. And do what she says she wants to do: show some humility.