Tomorrow, barring a U-turn by the Greens, the Scottish Parliament will endorse the First Minister’s call for another Section 30 Order from Westminster.

We know, of course, the tragic circumstances behind the deferred debate and division, although the fact it’ll take place shortly before Article 50 is triggered isn’t unhelpful: both the First and Prime Ministers will be despatching letters of intent.

The two-day Holyrood debate that began last Tuesday inevitably generated more heat than light, though it was striking – as Tom Gordon recently observed in these pages – how tired many of the SNP’s attack lines have become; many contributions moved little beyond reiterations of party press releases.

Even the First Minister’s heart didn’t seem to be in it. Her opening speech on this “historic” occasion was little more than an edited version of her conference speech, itself delivered at a two-day gathering in Aberdeen that felt low-key and, well, not very historic.

What’s become increasingly clear, meanwhile, is that the 2012-14 narrative about independence being a means to a “progressive” end was contrived nonsense designed to win over Labour voters. “Utilitarian” nationalism was always intended to disguise the existential basis of most arguments for independence.

Take a tweet from Colin Beattie, the SNP MSP for Midlothian North and Musselburgh and his party’s national treasurer, who asked for “a little old fashioned patriotism from the Tories and Labour” rather than their desire “to sell Scotland down the river”. And Roseanna Cunningham, a Cabinet Secretary no less, allegedly accused the Conservatives of calling for a suspension because they didn’t want to debate independence.

But then they were only taking their cue from the top, Nicola Sturgeon having abandoned “utilitarian” nationalism back in September. The “fundamental case” for independence, she wrote then, “ultimately transcends” the issues of Brexit, “of oil, of national wealth and balance sheets”. Amid tumbling oil revenues and unhelpful GERS figures this was, of course, a convenient way to frame the debate.

At the same time the First Minister clearly feels compelled to set out a more credible economic prospectus than that posited during the first referendum. Her conference speech even acknowledged the existence of a sizeable fiscal deficit – ie the difference between what Scotland raises through taxation and spends on public services – which would have been welcome had the SNP leader not subsequently retreated into the usual simplicities.

Naturally Westminster is blamed for the existence of this deficit, even though it arises because public spending per head of the Scottish population has consistently been above the UK average. In post-conference interviews, meanwhile, Ms Sturgeon offered an intriguing explanation of the Barnett Formula. “That money,” she told Sky News’ Sophie Ridge, “goes from Scotland to Westminster and comes back again.” Well, yes, but it also “comes back” with an additional £15 billion. Again, this absurdly simplistic – and deliberately misleading – framing of Barnett has clearly filtered down through the Nationalist ranks. During last week’s Holyrood debate I heard one SNP MSP heckle Labour’s Neil Findlay with the line that Barnett was Westminster “giving us our own money back”.

GERS deniers are also out in force, fortified by a blog from the Corbynista chartered accountant Richard Murphy which predicates its analysis on the mistaken belief that the figures are produced in London rather than Edinburgh.

In a recent interview with the Financial Times, Alex Salmond pushed the increasingly threadbare line that these official figures don’t accurately reflect the balance sheet of an independent Scotland, because they included the costs of nuclear weapons and the HS2 railway. Laying aside that the annual cost of the former is around £200 million and Barnett consequentials mean Scotland benefits from the latter, Mr Salmond also pointed to the prospect of higher growth via increased immigration, greater productivity and policy autonomy.

Again, nothing new there, although the mention of increased immigration gives a hint as to the basis of Andrew Wilson’s Growth Commission, apparently due to report over the next few weeks. The former SNP MSP is already busy PowerPointing his way around the country, and it seems a key point will be turning an independent Scotland into a magnet for highly-skilled migrants from the rest of the UK (also mentioned in Ms Sturgeon’s conference speech) and from within the single market.

The premise is that Scotland will inhabit a “sweet spot” between two Unions and thus clean up nicely. Mr Wilson doesn’t go in for conspiracy theories and takes the more rational view the GERS figures are more “pessimistic” than the reality of an independent Scotland, but nevertheless the aim of his “steady as she goes” approach to the economy is to reach parity with the status quo within a five-10-year timescale.

This begs an obvious question: what precisely is the point of further Brexit-like upheaval simply to get back to where we’re at in 2017 by 2027? To be fair, it’s at least a more credible prospectus than anything offered by the voluminous White Paper back in 2013, and that’s the point: what the SNP needs during a second referendum campaign (if it comes) is a credible line, not necessarily a deliverable one.

It still takes a huge leap to accept that thousands more skilled migrants are somehow going to plug an annual £9bn-15bn fiscal deficit, while the whole plan will flounder if a) it takes an independent Scotland a couple of years to get itself into the European Free Trade Association (EFTA) and b) the rest of the UK negotiates some sort of comparable access to the single market, thus removing the envisaged “sweet spot”. The plan also ignores the prospect of some companies (and highly-skilled individuals) moving south as quickly as others head north. Standard Life, for example, has made it crystal clear it wants to be closest to its largest customer base, ie not in Scotland.

More to the point, neither EFTA nor the European Economic Area are going to produce fiscal transfers to rival those currently provided by Scotland within the UK. The “economic case” for independence might be undergoing revision, but it still rests more on faith than empirical reality.