What’s the point? When I think about the state of British politics right now, that’s the question I can’t avoid. The entire country is strapped to a runaway mine cart, and the only option seems to be clinging on and hoping that the eventual crash leads to injuries rather than fatalities. Bailing out would involve a precipitous drop into the unknown. There are no good choices.

Two years ago, I was on a panel at the Labour party conference with an academic who – echoing a line once used by Bill Clinton’s lawyers about partisanship – said referendums were a “poison injected into the bloodstream of the body politic”. The phrase stayed with me, and I’ve wasted hours since then wondering what kind of poison the EU referendum was, exactly.

Curare? It has certainly caused paralysis, with European leaders openly baffled that Theresa May is still so vague about her position 15 months after triggering Article 50. At home, the legislation needed to unpick our relationship with Europe is overwhelming our legislators. As it staggers through the Commons, everything else – the revival of Stormont, fixing the trains in the north of England, reckoning with the catastrophic privatisation of probation services – simply has to wait. Our public services are not in good enough shape to be left ticking over for a decade while politicians and civil servants are consumed with trade negotiations and arguments about regulation.

Then there are those exotic hallucinogens, the ones that drive you mad if you lick the wrong Amazonian tree frog. The past two years have provided the truly trippy spectacle of the Tory party immolating everything it supposedly stood for on the altar of Brexit. (Austerity? Vitally important, right up until the DUP needed buying off.)

Some kind of temporary derangement seems the only reasonable explanation for Boris Johnson, allegedly a member of the Conservatives – remember them? About yea high, very big on how higher tax rates are unthinkable because rich people will move abroad? – responding to concerns about the post-Brexit economy with the achingly complacent line: “Fuck business.”

A moment’s pause seems appropriate here, in case we have become so inured to Johnson saying absurd things that this one passes by with barely a murmur. (Imagine if Jeremy Corbyn had said the socialist mirror image of this: “Fuck the poor. Seriously! They’re always complaining: ooh, I’m so hungry, ooh, I don’t have any shoes.”) The Foreign Secretary’s comments were so bad that even the impeccably loyal Daily Telegraph reported them – albeit shunted to page eight, which on the previous day had carried a picture of a troublesome bullock at a Cheshire agricultural show.

In a sane world, that remark ought to have buried his leadership ambitions, but a glance across the Atlantic suggests we shouldn’t assume a punchline can’t get elected. Johnson has recently expressed his admiration for Donald Trump, whom he presumably believes would sort out Brexit by calling Jean-Claude Juncker fat and drunk, declaring that Ireland doesn’t exist, and then inviting photographers to record him embracing a huge gold-plated statue of a bendy banana. The Foreign Secretary has learned from the orange-tinted master that if you create enough gaffes, it’s impossible to register them all. Nothing sticks to you if you are already covered in sticky stuff.

And so in the week Johnson casually torched his party’s entire reason for existence, he also flew to Afghanistan to escape voting for Heathrow expansion (or resigning to vote against it). His first big meeting was with the deputy foreign minister. I repeat: not even the foreign minister. The deputy foreign minister. The guy who does the foreign ministry’s IT support was presumably held in reserve in case of illness or last-minute childcare issues.

Ultimately, though, the poison of Brexit is a less showy one. It’s arsenic, isn’t it – that old favourite of vengeful nephews in Agatha Christie stories? Symptoms include nausea and irritability, and they creep up so slowly that the victims don’t realise they are being poisoned until it is too late.

As Brexit has dragged on, the conventions of British political life have been slowly eroded. How could Johnson resign, when he’s a leading Brexiteer? How could David Davis resign any of the five times he has threatened to do so, when he’s a leading Brexiteer too? How could Chris Grayling resign – for mucking up the trains or the prisons or basically anything he’s touched in his time in government – when he’s a leading Brexiteer? And so we add the principles of collective cabinet responsibility and basic ministerial competence to the pyre of things we no longer apparently need or want. A government should be bigger than any individual and yet this one remains diseased – because the referendum comes first.

Is the diagnosis terminal? Of course not. Our own incredible incompetence might force us into accepting an off-the-shelf deal, limiting the economic damage. The civil service might quietly thrash out a compromise on the customs union and then lock Liam Fox in a cupboard long enough to get it signed off. In time, Britain’s self-inflicted wounds might begin to heal.

What is less certain is the existence of an antidote. Jeremy Corbyn’s team is world-class at defeating its internal enemies – seriously, they should teach the kneecapping of Owen Smith’s leadership campaign in universities – but Labour still struggles to hold the government to account. (Boris Johnson’s survival is all the evidence you need of Corbyn’s weakness.) And holding another referendum would just inject more bile into our bloodstream.

I’ve spent my adult life believing that politics matters. But Brexit means I can’t stop thinking… what’s the point?