Vincent Gookin, the 17th-century English colonist in Ireland, wrote ruefully that “the unsettling of a nation is an easy work; the settling of a nation is not”. One way to understand why the Irish question has been so fatal for the Brexit project is to think about two islands and their degrees of unsettlement.

For Britain, the Brexiters have done the easy work of unsettling a nation. Both parts of Ireland, meanwhile, have been involved in the much harder business of settling a nation long torn apart by deep divisions of allegiance and aspiration. The great paradox of this moment is that the imperative of not endangering the fragile settlement on one island is profoundly unsettling for the other.

What is so striking about the political chaos at Westminster is the sheer wilfulness of it all. It is not a response to a plague or a famine, a war or an invasion. Britain’s crisis has deep causes, of course, though most of them (the effects of austerity, the loosening of the union) are self-generated. But at the political level most of it seems to be happening purely for its own sake. It is all gestures and poses.

Only a country that does not really know what the collapse of political authority looks like would play this game

The whole Brexit project has been, in Gookin’s terms, easy work. Make up lies about the European Union, throw patriotic shapes, get a smugly overconfident prime minister to call a referendum whose dynamics he does not understand, tell more lies, make promises you don’t believe in yourself, use stolen Facebook data to target voters with xenophobic images, tell everybody that they will have all the benefits of membership with none of the costs. Easy work, all of it: no plans, no complexities, no responsibilities.

On the morning of the referendum result in June 2016, the image that came into my head was that amazing trick that some people can do of whipping a tablecloth away while leaving all of the dishes and cutlery in place. Except the trick was being tried by a drunk. The idea was that a whole layer of politics that had been there for 45 years – the EU – could be whipped away and yet all the others – government, parliament, the law, the union itself – would not be upset. It was never going to happen. The trick, if it could be done at all, required a level of dexterity and coordination far beyond the capacities of the cack-handed and cock-eyed Brexiters. Instead of gasps of amazement, there was always going to be the cacophonous din of tumbling tableware.

Yet there’s another paradox: only a country that does not really know what the collapse of political authority looks like would play this game. To witness the wilful recklessness of seeking to plunge Britain into a Tory leadership contest at this moment of national crisis is to watch people playing with fire because they have never really been burnt. Modern Britain has had its troubles but politically speaking it has been remarkably stable. A two-party system has survived. Political violence is rare. Even the nationalist movements in Scotland and Wales are civic, rational and democratic.

But what we see from the outside in the past three years is a country pushing its luck. There seems to be an assumption that the political system can discredit itself as much as it likes with no long-term consequences for the very idea of political order. All we outsiders, scarred as we are by very different memories, can say is: good luck with that.

Would you trust the settling of your nation to a process that is so utterly unsettling its own?

There is, of course, a part of the UK that has had no such luck. Northern Ireland’s Troubles are part of the wider story that Gookin was alluding to in the 17th century: the unsettling of Ireland that, as he suspected, would not be so easy to undo. We talk casually of the Belfast agreement of 1998, also known as the Good Friday agreement, as a “settlement”, but the word has a much deeper resonance. The settling process has been going on for a long time now: we’re just marking the centenary of the 1918 Westminster general election in which Sinn Féin won a majority of the Irish seats, leading to secession, guerrilla warfare, partition, independence and the resurgence and eventual ending of the Troubles.

This settling has not been easy work. It has been built on terrible human suffering. It has demanded of politicians (very much including British ones) patience, intelligence, planning, compromise, creativity and the acceptance of personal moral responsibility for the consequences of what is done and not done.

A big part of this process has been that most delicate, precious and powerful of feelings: trust. The settling of Northern Ireland has been possible because Britain and Ireland came to trust each other. By working together on the peace process (and, ironically, as very close allies in the EU), Irish and British leaders and diplomats came to believe implicitly in each other’s good faith. One of the tragedies of Brexit is that this faith has been broken.

There is, in Brexitland, a sense of outrage that the Irish government has not taken Britain at its word when it says that there will never be a return to a hard border in Ireland. The message all along has been: trust us, it will be fine, no need for a legally binding guarantee. But would you trust Theresa May who swore by her red lines until she crossed every one of them and who insisted she would not call an election until she did? Does anyone on Earth trust Boris Johnson, who was foreign secretary for much of this period and has ambitions to be the prime minister after Brexit? Could anyone have faith that David Davis would even understand what he had signed up to, let alone implement it?

But this is not just about individual politicians. The bigger question is: would you trust the settling of your nation to a process that is so utterly unsettling its own? Trust in political assurances requires some reasonable sense of predictability and security. You have to know that there are stable democratic institutions capable of keeping promises and seeing things through. Would anyone looking at the goings-on in Westminster over the past fortnight seriously believe that Britain is a settled democracy?