It’s getting so predictable, you could almost set your watch by it. Whenever this government has run out of other ideas on Brexit, it summons the hoary old ghost of no deal to frighten the children. And so once again this morning, cabinet has been summoned to discuss the merits of what the ardently pro-leave Penny Mordaunt calls a “managed glide path” out of the EU, which as a euphemism for crashing a plane into the side of a mountain beats even Labour’s “jobs-first Brexit”. Someone briefs the Sun that all other government business will be parked, all the better to concentrate on adopting the brace position. The perennially loyal health secretary, Matt Hancock, is wheeled out to insist earnestly that the NHS is prepared for no deal now, which may come as a surprise to anyone working in the NHS, and so should everyone else be.

Brexit: cabinet meets to discuss ramping up plans for no deal Read more

And the response in Westminster will largely be: oh please, not this again. Not another crude attempt either to scare MPs into voting for Theresa May’s essentially defunct deal, or to scare the EU into offering more concessions, or preferably both. Downing Street has itself all but admitted that the idea of a carefully stage-managed no-deal is a non-starter, given the EU has said it won’t even open discussions about such a thing until after we leave, and it beggars belief that May is seriously just planning to wing it. So presumably businesses too are meant to understand that ministers don’t really mean it, except as a negotiating tactic.

Yet what makes this form of moral blackmail so wickedly irresponsible is that it risks spiralling out of the government’s control. There is only so long employers can hold off from activating contingency plans for a no-deal Brexit when the government is very loudly and clearly signalling that they should do so, with ministers asked to approve letters to thousands of businesses urging them to plan harder for no deal. And once those decisions are made, they can’t be unmade. Headquarters cannot be moved back to Britain on a whim, and jobs cannot be reinstated. Sales lost because customers get jittery and put off making major purchases won’t be so easily recouped, either. Nor can we unspend the billions government departments are being ordered to spend on planning for something most of Whitehall still thinks would be madness, at the expense of domestic problems crying out for attention. (There is something deeply odd about a pro-remain chancellor demanding to know why ministers have spent only a third of the pot set aside for no-deal preparations, when the obvious answer is that they think there are better uses for public money than spraying it around on something they still can’t quite believe will be allowed to happen.)

Technically speaking, it’s still not too late for all the major parties to agree that they could not in all good conscience allow a no-deal Brexit to befall the country. That would clear the way for a decision on the only realistic options left: May’s deal, revoking article 50, or somehow trying to open negotiations on an alternative deal (the last two of which would probably require a second referendum or a general election first, and the final one of which probably requires some sort of miracle).

But giving up the ridiculous pretence that no deal is a workable outcome doesn’t suit May, because it would expose her to the full wrath of leavers within her party. More curiously it doesn’t suit Jeremy Corbyn all that well either, since any narrowing down of the choices forces the opposition leader closer to the point of actually choosing something. This empty threat fools nobody, yet seemingly cannot be withdrawn, and thus has begun to take on a life of its own. And all the time parliament inches closer to the thing that almost nobody wants, but almost everyone seems powerless to stop.

• Gaby Hinsliff is a Guardian columnist