THE paradox of Buridan’s ass goes like this: hungry and thirsty, the silly animal is set an equal distance between a pail of water to quench its thirst and a tasty pile of hay. Paralysed by indecision about whether to wet its whistle or answer the grumbling of its stomach, the donkey just stands and stares, caught between its appetites. Parched and perishing, it starves to death.

Welcome to the dead donkey phase of Brexit – perhaps the terminal phase of an interminable process – as paralysis reigns. As the clocks count down, with less than two weeks to go till exit day, MPs are still fussily Goldilocksing the alternatives.

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Diehard Brexiteers oppose a deal which would guarantee Britain leaves the EU by Friday, March 29 – because this Brexit apparently isn’t Brexity enough. In the Commons, meanwhile, People’s Voters on the Labour benches prefer to sit on their hands, because they’d rather support a second EU referendum at some hypothetical point in the future.

Everyone has a first order preference which isn’t on the order paper. And as Times columnist Alex Massie has rightly observed, until these first preferences are swept away and parliamentarians seriously engage with their second preferences, the rigmarole can only continue. To adapt the late great Gerry Rafferty, our MPs are content to waste day after day, watching and waiting for a sign, going round in slow motion, interminably. This must end. And soon.

It is easy to be rude about the Prime Minister. There is much to be rude about. But interminability is one of Theresa May’s great virtues. Some say they feel sorry for the Prime Minister. I don’t. She may have boxed herself in with foolish red lines. She may have surrounded herself with dangerous fools. After David Cameron fled office, she needlessly embraced a negotiating position which was narrow, poisonously partisan, making no effort to recruit a cross-party consensus around what version of Brexit to pursue.

She pandered relentlessly to the double-breasted suit brigade in her own party and chose to put herself in hock to the erratic howler monkeys in the DUP. Scottish interests and perspectives were consistently marginalised and ignored. On the independence question, she is shamelessly undemocratic.

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But having made all of these mistakes and misjudgements, having managed to strike some kind of accord with Brussels, she is expending her last full measure of devotion to drag her deal through. It is interminable to watch. All sorts of indignities are being practised and ignored in this joyless journey. After the first meaningful vote miscarried to the tune of 230 votes on January 19, many speculated she’d be forced from office. She grinds on. Ministers are resigning and rebelling. She grinds on. A second meaningful vote falls by 149 votes – yet she grinds on.

In its charmless way, the Prime Minister’s doggedness is almost heroic. Despise her, by all means, but don’t pity her. You may think the whole enterprise misguided. You may think it the political equivalent of making a political desert and calling it agreement. But fair’s fair: that woman has grit. And unlike many other participants in this Brexit saga, she has a clear plan.

But where can she turn now? Having done the Prime Minister no favours before her second meaningful vote, Theresa May’s Attorney General Geoffrey Cox has belatedly pulled a rabbit from the hat. Inspect the creature closely, and you’ll notice it’s a fairly scabby-looking specimen – eyes a shifty late-night pink, fur patchy. It goes by the name of “the Vienna Convention” – and some Tories are hopping with excitement about what this myxomatosis bunny might justify.

“It is extremely important to remember that there is always a right to terminate a treaty unilaterally if circumstances fundamentally change,” the Attorney General told MPs this week. “There is no question but that we have a right to exit if those circumstances apply.”

Pressed by party colleagues about what these circumstances might be, Cox raised the spectre of “some fundamental political change in Northern Ireland” which could give the UK the right to rat on the withdrawal accord struck with Brussels. This was music to havering Brexiteer ears, and in the days that have followed, barrack-room lawyers have been pouring over the convention to see if it might be just the fig leaf Theresa May’s wavering colleagues need to forget their disquiet about the Northern Irish backstop.

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So what is it? Struck in May 1969, the Vienna Convention aims to set out a world code against which treaties can be interpreted. The UK is a party to the convention, as are the overwhelming majority of EU states. Across 85 articles, it deals with technical questions of signatures and ratifications – and, critically, sets out circumstances when states can legitimately break international deals they’ve struck.

And Cox is right to this extent. Article 62 sets out conditions where a “fundamental change of circumstances” would allow a state to slip its treaty obligations. But less helpfully for the government, there are conditions attached. And they’re stringent. As the Vienna Convention makes clear, the change in circumstances must be “unforeseen” by the parties to justify departing from an agreement. The International Court of Justice has been crystal clear. “The stability of treaty relations requires that the plea of fundamental change of circumstances be applied only in exceptional cases,” it said.

There is nothing more predictable than ongoing friction about how and by whom Northern Ireland is governed. The backstop, in its bones, is an insurance policy against the eminently foreseeable possibility that the UK can’t devise a workable alternative to erecting a palisade around the six counties.

The Conservatives may be labouring under a collective delusion in British exceptionalism. In their imagination, John Bull may be entitled to do whatever he likes. But whether they like it or not, like the law of gravity, this country is still bound by international law. Britain can’t act like a bad debtor without consequences.

This was meant to be castle in the clouds time. HMS Britannia would re-launch on a sea of goodwill, surging forward having secured the snappiest trade deal in human history with our European cousins. To say it hasn’t exactly worked out like that – well, let’s just call that masterly understatement. Built on foundations of marshmallow and old rope, Brexit’s fairytale castles have all crumbled and now the Brothers oh-so Grim are rewriting the endings.

Give Davis, Fox and Leadsom the quill, and Rumpelstiltskin would be convicted of attempted child kidnapping, Rapunzel’s mother for wilful child neglect. While Goldilocks is pondering the umami of her porridge, she wouldn’t hear the scuff of 12 claws on the cave floor, or the grumble in baby bear’s stomach, or sense the huge paw poised to swing.

In the Brexit version, most of the seven dwarves would die in industrial accidents. A runaway minecart takes out Grumpy. Sleepy’s undiagnosed narcolepsy results in a fall into an industrial gem cutter, for which his family received no compensation thanks to swingeing cuts to Brussels red tape.

Sneezy’s persistent cough is eventually identified as mesothelioma as a result of decades of exposure to emerald dust due to the mine’s unsafe working practices. The dig physician – Doc – is subsequently arraigned before the General Medical Council and struck off for malpractice.

Dopey, of course, is appointed Secretary of State for Transport in Theresa May’s government. He Graylings it. And as for Snow White? Well, toxicologically speaking, that poison apple probably does permanent damage to her kidney function, and she now undergoes regular dialysis – kiss or no kiss from some creepy minor royal who is in the habit of smooching hot cadavers he comes across.

Nobody lives happily ever after.

The fairy tale’s over. Reality bites.