‘WHY?” is a kid’s question, and as a result, often a very good question. So let’s train this simple question on the Scottish Government’s current negotiating position on the Brexit Bill. Why does Nicola Sturgeon’s administration want the wash of powers which will return to the UK once Britain splashes out of the EU? There’s a boring answer, the political answer, its rhetoric now echoed countless times in countless parliaments across these islands.

You know the line. Say it with me. All together now. “Power grab, power grab, power grab.”

READ MORE: Russell makes Brexit Bill plea to Archbishop who is backing power grab

The rhetorical battlelines between the UK and devolved administrations are now clearly picked out. The banners fluttering over Theresa May’s troopers read “common sense”, “trade deals” and “UK single market”. Above Carwyn Jones and Nicola Sturgeon, by contrast, the legend reads “nothing about us is for us without us”.

“Consent”, the devolved administrations argue, must be an indispensable precondition of UK policy frameworks after Brexit. “Consultation” won’t cut it.

You’ve also heard the authorised version of why this is a constitutional mischief.

READ MORE: Richard Leonard gets confused at FMQs about devolved powers

The Scotland Act is built around a reserved powers model. Everything which is not reserved to Westminster – is devolved. Ipso facto, a fortiori, quad erat demonstrandum, the Brexit powers must flow to Edinburgh, Belfast and Cardiff, rather than stagnating in London.

That isn’t to suggest Scotland should operate in splendid isolation from the rest of the UK. There are plenty of good reasons why the governments of these islands would see the advantages of striking deals with one another about how things will work after Brexit day. But as the devolved administrations have insisted, it is one thing to agree to iron out the tough details on the basis of equality. It is quite another to have whatever callow pinstripe Theresa May next elevates to high office unilaterally deciding ex cathedra how things are going to go down.

I’ve considerable sympathy with this argument, but it only gets us so far. One of the vices of the modern SNP is its tendency to become process-focused rather than explaining why the process might matter in simple terms. Demand a referendum, but neglect to explain to anyone why and how it is necessary; singing canticles about power grabs, without humanising what powers we’re talking about, and why they matter.

READ MORE: Tories furious at 'national humilitation' on post-Brexit passports

I like a partisan barb as much as the next guy. There is comfort in an entrenched argument. When all your lines are scripted, it absolves you of the pain, panic and boredom of thinking for yourself. But none of these official lines answers the more fundamental question of why the Scottish Government wants or needs control over big swathes of EU law after Brexit, or what Scottish ministers are likely to want to do with their new autonomy. Why might the First Minister be keen for fisheries policy to be determined, at least in comradely parallel, with DEFRA after 2021, for example? What has the Scottish Government to gain from being responsible for agricultural subsidies?

Part of this is muscle-memory. For most Scottish Nationalists, it is reflexive – autonomy should always be maximised. But with power comes responsibility, and with responsibility, angry crowds of voters with ready access to threshing implements and fishhooks, inclined to do you harm. It is all very well chanting “power grab, power grab” on loop, but if Holyrood manages to grab the lion’s share of Brexit powers, it will inevitably expose tensions in the party about where to go from here.

Two incompatible dynamics are already at work. In the first corner, control of great swathes of the EU acquis will allow Scottish politicians to adhere to some, if not all, forms of EU regulation. For the long-sighted Scottish nationalist, interested in maintaining Scotland’s convergence with EU rules with a view to acceding to the bloc as an independent country down the line – this is no minor detail.

It seems eminently plausible that Tory or Labour ministries in Westminster will be inclined after 2019 and 2021 to deviate from EU law where a public will can be found to do so. Holyrood control offers scope to temper any divergence between Scottish and EU regulations, which the sons and daughters of the Better Together campaign might be inclined to make hay with in any future referendum campaign.

READ MORE: Davidson under fire for her fishy post-Brexit story

But Nicola Sturgeon’s cod and haddock caucus will likely have other ideas – as will fans of keeping Calmac’s ferries churning through the foam without the market discipline of subjecting its bids to tender and the demands of EU competition law. It seems reasonable to anticipate these voices in the party will present the First Minister with powerful arguments for the SNP to depart from EU law to help shore up wavering constituencies and see off flanking manoeuvres if and when Scottish Ministers gets their mitts on the appropriate powers.

The Nationalists have been enjoying Tory discomfort this week – and no wonder – after Ruth Davidson’s latest line in the sand on fishing was washed smartly away by the indifference of her London colleagues. North eastern Tories may have faces like melted wellies this week. I don’t begrudge their opponents a cackle – but the SNP leadership seems curiously reluctant to defend the logical implications of party policy.

In response, Tory MP Ross Thomson tweeted – characteristically gormlessly –that “the SNP want to drag Scotland back into the EU”. Many Scots will be content for the Scottish Government to fetch the lasso. But there is a cutting edge to Thomson’s blunt reasoning here, which was further developed by one of Theresa May’s ministers this week.

“Although Scottish nationalists talk about all these powers coming back from the EU,” Baron Keen of Elie observed, “let us remember that they do not want them. If they get them, they want to give them back to Brussels, because they want Scotland, as an independent country, to remain in the EU — and, if it leaves, they want it to join EFTA and the single market. Therefore they will return all the powers they are talking about if they get their ultimate aim.”

Is the Learned and Noble Lord mistaken? Nationalist responses to this kind of Tory snark have ranged from harrumphs, to tu quoques, to plain old blusters.

But shorn of its party political overtones, isn’t this precisely the party’s argument about where the Brexit powers ought to lie? If this is a defensible position – and I believe it is – if this is party policy, and every indication from Bute House is that it remains so – and if it is the prospectus which any future referendum on Scottish independence will be fought upon – it needs to be defended, not dodged or chortled off or deflected from.

It is one thing to argue that decisions shouldn’t be taken unilaterally in Whitehall. EU decision-making is not, as Keen implies, identical to giving UK Governments the whip hand.

But it is a reminder that state building isn’t easy. Too often, the SNP have been tempted to sacrifice long-term strategic coherence for short-term tactical victories. But while you enjoy Ruth Davidson’s well-earned discomfort, remember this: you can’t call out woolly Scottish Tory thinking and have a head full of cashmere yourself. I swear to you, eventually, the punters will notice.