A very important thing is happening in Scottish politics this week, and to better understand it we should reflect on a very trivial thing that happened last week.

That trivial thing was the outbreak of inanity which greeted the news that the US was lifting its tariffs on Scotch whisky. Removing these trade barriers had been a priority for the UK and Scottish Governments for some time.

Instead of rejoicing at the announcement, the governing class gave us another display of the snide, vacuous politics that has earned them the contempt of the general public and will doubtless be reflected in the turnout for Thursday’s election.

First up was the SNP, which attempted to hog all the credit for Donald Trump’s decision. Next up was Labour and other opposition parties, which poured scorn upon the very notion that John Swinney deserved credit.

Cue sundry memes, with mocked-up SNP social media posts congratulating Swinney on everything from Creation to the fall of the Berlin Wall.

Behind the humour, a vicious war was being waged to frame the tariffs news and, a few days out from an election, to assert ownership of a change that will be worth considerable sums to the economy and the exchequer.

The SNP has a reasonable claim. Swinney did lobby the President in person to get the tariffs scrapped and has been noticeably muted in criticism of the easily-offended Republican, deftly sidestepping many a Green invitation to stick a thumb in Trump’s eye at First Minister’s Questions.

But the UK Government has committed considerable time, effort and resources to the withdrawal of tariffs, and frankly its time, effort, and resources reverberate much louder in the corridors of Washington DC than the words of a First Minister.

Plus, Westminster had a secret weapon in the King. Trump is positively gaga for a monarchy his country was founded on overthrowing. Whatever the sociology behind this, Charles used it to his advantage on his recent visit Stateside.

So Swinney, Whitehall’s negotiators and the Sovereign each played a part, though all probably owe a tip of the hat to the US whiskey sector, which has turned against tariffs amid retaliatory levies, a shrinking domestic market, and an unprecedented bourbon surplus (16.1million barrels and counting) at the mercy of Kentucky’s barrel tax.

With midterm elections in November, the lobbying of a deep-pocketed industry and layoffs in spirits-producing southern states might have had more to do with the White House’s decision than is realised on this side of the Pond.

When it comes to who deserves credit for ridding us of whisky tariffs, with apologies to Clark Gable, frankly my dear, I don’t give a dram. What matters is that our distillers gain access to a huge export market. Our nation’s economy should be our top concern. Leave the politicians to their petty point-scoring.

Among the absurdities of this episode is the failure of the opposition parties to see something staring them in the face. The real story was not that Swinney was claiming credit for the efforts of others but that Swinney was claiming credit at all.

Remember, this is the First Minister who consistently blames his government’s every failing on its lack of powers and his assertion that all the important shots are called in London.

When grilled on Scotland’s sluggish economy, Swinney’s answer always consists of ‘Brexit’, ‘Truss’ and a whole lot of froth. 

When questioned on NHS Scotland’s dismal performance against waiting times targets, and even though the NHS is completely devolved to Edinburgh, Swinney bleats about UK immigration policies and their effect on recruitment. 

When asked to account for low productivity and basement-level business confidence, the blame invariably lies with Westminster.

Swinney himself knows just how powerful the Scotland Act makes his office and his government. His response on tariffs gave the whole game away.

When the news came through, all those terribly principled complaints about Westminster hogging trade and foreign affairs powers suddenly evaporated.

The Scottish Government was no longer hindered by such considerations. The First Minister had been able to manoeuvre around them somehow and get the US President to change his trade policy.

Now, you might say this is just politicians being politicians, and to an extent it is, but it is also a demonstration of the ratchet effect of devolution: when things go right, Holyrood gets the credit; when things go wrong, Westminster gets the blame.

For 19 years now this ratchet has turned – click, click, click – in the Nationalists’ favour. Did something work? Hurrah for the SNP! Something went wrong? Well, it’s hardly the SNP’s fault, now is it?

When scrutiny is this shallow and accountability this flimsy, it is no wonder that Scotland sees the policy outcomes it does. At Holyrood, the SNP has pioneered a new model of political administration: non-responsible government. All the trappings of power without the duties of office.

Pledges are untethered from delivery, inputs severed from outcomes. The SNP asks the voters for power on a promise to produce certain results; the voters give it power and the SNP fails to produce the results; when asked why, the SNP says the necessary powers lie elsewhere and have all along.

Nationalists often lament the current arrangements as a constitutional trap, and it is certainly telling that they consider the opportunity to govern a dastardly snare set by their opponents.

Yet if devolution is a barrier to their political ambitions, it is the most gilded of cages. While their ultimate goal of independence lies on the other side of the bars, it is those same bars that deflect scrutiny of the sort that might make even committed nationalists consider the wisdom of entrusting them with a sovereign state.

Two decades on from their 2007 victory, the SNP remains what it has always been and always will be: a party of campaigning, not of government. Promisers, not deliverers. Slick salesmen for a shiny tomorrow who won’t be taking any questions at this time.

John Swinney says that after this election he intends to lead his party into the 2031 vote, too. That is a matter for the voters and if they opt for it those who cling to the devolution experiment have no choice but to accept it. Democracy will have spoken.

That is what is on the ballot paper on Thursday. There is a party which wants all the power without the responsibility and all the credit without the results. Have the voters at last had enough of non-responsible government or do they want five years more – and perhaps more after that?

Voting to reject this sorry state of affairs might seem like a puny protest when the SNP is all but guaranteed to win and when no credible alternative government presents itself. Protest is all that’s left to us but I’m not so sure it’s as puny as it seems.

A vote against the SNP is a vote against the whole rotten, corrupt, failure-drenched status quo and an angry, frustrated, heartsore cry for something better than this.