Sometimes you can be right and still lose the argument. Sometimes you can be on the moral high ground and still find it giving way underneath you. Much to my surprise, this is where Nicola Sturgeon has found herself this week - making an excellent point about the flaws in the EU Withdrawal Bill but making it so badly that she risks undermining support for her arguments, her party, and, most importantly for her followers, the nationalist cause in general.

Most of the problem is down to the language the First Minister has chosen to use. Discussing the bill on television yesterday, the Scottish Brexit minister Mike Russell was sounding pretty positive on the whole - possibly because, behind the scenes, there’s a suspicion that Mr Russell would have accepted the deal that’s currently on the table, as the Welsh have done. Whatever the truth, Mr Russell was playing Mr Reasonable to a T. There was, and still is, hope of a deal, he said.

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But compare that to Nicola Sturgeon’s response. Writing in the Sunday Herald yesterday, the First Minister forecast a bleak future for the Scottish Parliament in a post-Brexit Britain. Be under no illusions, she said, the Tories will “demolish” Scottish devolution. She also summoned up a scary ghost from the future: Jacob Rees-Mogg as Prime Minister “trampling all over Holyrood’s authority” and warned that a future Tory government might interfere in the Scottish NHS. There was also multiple use of the SNP’s phrase du jour: “power grab”.

Now, we know that this kind of edge-of-the-cliff rhetoric, this political shrieking, plays well to Ms Sturgeon’s core support (which is probably why she’s doing it) but it certainly doesn’t serve the Scottish Government’s central argument on the Withdrawal Bill, which, far from being hysterical, is extremely sound. Essentially, Scottish ministers are appealing to one of the founding principles of devolution, which is that the Scottish Parliament has control over devolved areas - and anything that is not explicitly said to be reserved is devolved. The EU Withdrawal Bill in its current form would transfer powers from Brussels to London in areas that are traditionally devolved to Holyrood and so fails to respect that convention.

So why can’t the UK Government simply accept this and do what it has always done, which is to seek the consent of the Scottish Parliament to act in areas that are devolved? Mainly – and sadly – it’s because of all those unlikely, sun-lit trade deals we’ve been promised after Brexit. UK ministers have come a long way towards a compromise by reducing the number of areas they seek to control from 111 to 24, but, if it is to have any chance of achieving those trade deals, the UK Government needs control of the core 24 policy areas that are in dispute - and the last thing Brexiters want is a grumpy, unco-operative Scottish Parliament getting in the way.

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However, the failure to reach a compromise is also a major failure of trust – on both sides. Mr Russell said yesterday that the Scottish Government would never unreasonably withhold agreement to new legislation in the 24 policy areas and clearly expects the UK Government to trust him on that. The UK Government has also said it expects to be trusted on its commitment that if the Withdrawal Bill goes ahead in its current form, it would abide by the conventions of devolution. Both sides are saying the same thing: I can be trusted, but I wouldn’t trust that other guy.

Of course, it’s up to you who you believe in the end, but the fact is that since devolution successive UK Governments have respected – and indeed expanded, albeit under duress - its conventions; the SNP’s life work, on the other hand, is to undermine the UK Parliament. Could the Scottish Government be trusted not to exploit the situation every single time the UK Government sought its consent post-Brexit? Much more likely is a repeat of what we’ve seen from Nicola Sturgeon over the weekend: more talk of the Tories demolishing Scottish devolution and stomping over Holyrood’s authority, a kind of never-ending grievance, always looking for the next reason to rise up.

From the First Minister’s point of view, the big gamble is that the hyperbole will help her get her way – and I suspect she’s right; the UK Government is much more likely to capitulate than the SNP. But I wonder if she’s considered the long-term effects on her support in Scotland? After the Brexit referendum, we saw the Sturgeon hyperbole on Brexit, independence and the Tories rolled out and it backfired. Then we saw the same thing at the General Election in 2017 and the result was the SNP losing one-third of its seats.

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And yet here we are, in the middle of the Brexit debate, with the First Minister performing the same form of political self-harm. There aren’t many disputing Ms Sturgeon’s central argument that the Scottish Government should have consent in those last 24 policy areas. But the language of power grabs and the demolition of Scottish devolution sounds exactly like the kind of language we heard after the Brexit vote and then again at the last General Election: a little loud, a little obsessed. Perhaps the First Minister should take note of the interesting phenomenon found in cognitive science called selective filtering: if you hear a repetitive phrase or sound often enough, you start to filter it out and listen to something else instead.