It called to mind Bill Clinton’s sublimely evasive remark when questioned about the veracity of statements he had made about the nature of his relationship with Monica Lewinsky. “It depends upon what the meaning of the word ‘is’ is,” said the president. David Davis, when asked by a House of Commons committee to explain why he had failed to provide anything adequately resembling the Brexit impact assessments that had been demanded by parliament fell back on an extraordinarily devious defence. There are no “impact assessments” and never had been.

The secretary of state did not deploy air quotes in his testimony but the implied inverted commas carried the full weight of his argument. It was, in essence, that MPs had voted to insist on the provision of something that didn’t exist and so there was no real need to question whether or not he had complied.

He had instead served up material that might help committee members navigate complex Brexit-related issues, while excluding (or actually allowing officials to exclude) anything that might be commercially sensitive or that might compromise the UK government’s negotiating position. But, in Davis’s terms, that is not the same as an “impact assessment” and MPs’ disappointment at the quality, breadth and detail of their hoard stems from some unfortunate misunderstanding. Semantics. You say “impact assessment”, I say “sectoral analysis”, pot-ay-to, pot-ah-to, tom-ay-to, tom-ah-to, let’s call the whole thing off ...

MPs feared a David Davis cover-up. Worse, he had nothing to hide Read more

Jacob Rees-Mogg came to Davis’s aid with a delicate under-arm question, inviting the secretary of state to agree that, given the non-existence of “impact assessments” the provision of non-impact-assessments was the very opposite of failure to comply with parliament. It was, indeed, going above and beyond the call of duty; an act of magnanimous transparency. If anything, the fault here lay with opposition MPs for having the temerity to request sight of an invisible thing. Davis demurely agreed.

So how did this misunderstanding arise? Davis had previously referred to work undertaken in “excruciating detail” to consider the economic consequences of quitting the EU under various scenarios and for various sectors of the economy. (But he claims never to have called them “impact assessments”.) Setting aside the technical definition, the question still arises of how meticulous, forensic work undertaken over a long period of time behind closed doors in Whitehall morphed into stuff you could find on Google; what one committee member described as a “cuttings file”.

One explanation is that the redactions removed all the valuable material. This is possible but it requires believing that the department had too much stuff to share and required time only to sift and remove it. Yet the permanent secretary, Philip Rycroft, giving testimony after Davis, essentially admitted that the opposite was true. He had been surprised by his ministerial bosses’ offer to parliament and had promptly required to oversee a process of rapid collection and collation of data. In other words, DexEU hasn’t spent the past three weeks taking things out. It has been scrabbling around for stuff to put in.

Facebook Twitter Pinterest ‘The more convincing explanation is that Davis was bluffing.’ Photograph: Thierry Charlier/AFP/Getty Images

The more convincing explanation is that Davis was bluffing. He presumed that there was a lot of detail around somewhere, recognised at some level that it was the sort of thing that certainly ought to exist and didn’t expect ever to be forced to admit that it didn’t. And when parliament called his bluff, he doubled down, played along with the idea of impact assessments and let his civil servants try to do a year’s worth of government homework in less than a month.

Through all the bluster, swagger, faux joviality, arrogance and complacency of the committee’s star witness one sharp truth shines through. A decision was made last summer to define Brexit as a requirement to leave the single market and the customs union – an action that would quite obviously have enormous consequences for the UK’s economy – and the secretary of state notionally responsible for enacting that decision at no point set about the task of rigorously investigating what those consequences might be.

And whatever half-baked understanding he had of the issues was not one he ever intended to share with MPs or the British people. He still has no intention of sharing it. Whether that is a case of cynical, ideologically-motivated subterfuge, laziness, stupidity or some psychological aversion to the confrontation of difficult things only Davis himself can know for sure.

It is revealing, too, how heavily Davis relies on the assertion that vital data had to be kept secret lest it fall into the hands of the European commission and inform its negotiating stance. The inference here is that there might be things about the whole Brexit process that the ingenious UK side has thought of but the dull-witted Europeans haven’t thought of yet. The process of the talks so far at every turn has demonstrated the opposite to be true. The pattern has been Europeans flagging up problems well in advance and British politicians denying the existence of those problems, then failing to address them with practical solutions.

Sector-by-sector Brexit impact forecasts do not exist, says David Davis Read more

But a deeper subtext to the Davis argument (one he might not even consciously know) is that it would be a mistake to let the EU know what the UK’s judgment of Brexit’s impact on the domestic economy would be because the impact is so harsh. In other words, if the commission knew that the UK is actually afraid to go through with some of the harder Brexit plans promoted by Theresa May, the talks become a dictation of the terms of surrender. That is indeed the way things have played out so far. The great fear of exposing the government’s hand flows from the relative weakness of the cards it holds.

The bluffer fears being called. Of course, the EU side has understood the relative strengths and weaknesses of the UK position for longer and far better than May or Davis. The prime minister and her secretary of state have been kidding themselves. To sustain the delusion, they have tried to avoid scrutiny in parliament and, by extension, deceive the British public. Is the whole of the government’s Brexit strategy built on lies and obfuscation? Well that depends on what your meaning of the word “is” is.

• Rafael Behr is a Guardian columnist