Exit from the EU poses a threat to the international liberal order. In the long run, it is untenable.

The foreigner’s political eye can be innocent, failing to see the tangled vernacular in an unfamiliar land. But it can sometimes see the big political picture with greater clarity. Foreigners can see what Americans struggle to accept about their terrible gun culture. Foreigners can see that Italians will demean their country if they re-elect Silvio Berlusconi’s party.

What about foreigners’ views of Britain? What do their eyes see that we too often miss? Here are three examples, all garnered from just the past few days. They are widely representative.

First, politely, Wolfgang Ischinger at the Munich security conference last weekend. Ischinger is an anglophile, a global thinker, a former German ambassador to Britain. As chairman of the Munich conference, he interviewed Theresa May at the weekend, very deliberately saying to her that Brexit was “highly regrettable” and that “Things would be so much easier if you stayed.” May smiled icily at this, like the political hostage she is, as the letter from Jacob Rees-Mogg’s deregulatory fanatics this week so cockily confirms.

Second, frustratedly, in a bar in central London this week, one of my oldest friends. He’s a Canadian, with lots of British roots and experience, just back from a trip to Asia and passing through London. He suddenly pushed back in his chair and said of Brexit: “This just has to be the stupidest decision that any democracy has ever taken.” The accent made it specially eloquent and damning – “the stoopidest decision”.

And third, angrily this time, there is Fintan O’Toole in the Irish Times this week with a blisteringly sarcastic column. Britain is a cat up a tree, he writes. It needs to climb down but it hisses and claws at those who clamber up ladders to offer a hand. It’s time for the EU to cajole the hissy cat out of its tree with 15 exasperatedly contemptuous concessions to England – yes, O’Toole gets it that Brexit is mainly about the English. Things such as being allowed to win penalty shootouts, compelling Spanish-language atlases to call the Malvinas the Falklands, and sending children up chimneys.

These are three views from three people who do not know each other but who each know Britain’s oddities. Brexit is a pity. Brexit is stupid. Brexit is an act of English self-love. It is obvious that there are points to be made against each of the three foreign critics. Yes, the German political class is far too complacent about the nation state and Europe. Yes, my Canadian friend ought to know that no political campaign is won by calling people stoopid. And, yes, O’Toole ought to know there is more to Britain than boozy, brassy tabloids and infatuation with the war – sometimes. But the bigger picture is that all three are right. They get it. And they speak for the overwhelming majority of the rest of the world – or at least the bit of the world that doesn’t welcome the weakening of the rules-based order, of international standards, and of open, pluralistic liberal societies. The Germans are right to be sad, the Canadians right to be annoyed, and – in particular – the Irish are right to be angry.

Politically and morally, Brexit will always comes back to Britain’s relationship with Ireland. There can be no hard Brexit without a border in Ireland, and the choice you make on this defines you. Six days ago, the former Northern Ireland secretary Owen Paterson, a recklessly hard Brexiteer in the Rees-Mogg mould, endorsed the view that the Good Friday agreement, which brought 30 years of killing and rioting to an end, has “outlived its use”. This is a resonant moment. It is the moment when the Brexit fanatics appeared to be happy to take the risk of Irish people killing each other – and killing British people too – for the good of Brexit. Actually it’s more. It is the moment when parts of the Tory party seemed to be saying that 20 years of peace in Northern Ireland was positively undesirable because it had legitimated the gunmen. Not just not worth preserving – but positively worth destroying. That’s more than a pity, and it’s more than stupid. It is dishonourable. It’s also unneighbourly.

When an electorate does something wrong, such as elect Berlusconi or make Donald Trump president, or vote for Brexit, it isn’t the end of the matter. Yet there are always contrarians who insist on blaming the defeated side rather than the winners. It’s the fault of the previous consensus, they say. There was always something rotten in the established view, they insist.

Get over it, they continue. Look for the opportunities lurking in the setback. That’s what a group of so-called “brains for Brexit” are now doing. These academics think that anti-Brexiteers should move on, be more open-minded about their own faults, and think afresh about the possibilities of Brexit. They think everything isn’t really as awful as the remainers claim. Some interesting people are involved in this little project, people with ideas that are worth thinking about, people who are worthy of serious respect. Some of what they say is genuinely worth considering, as alternative views always are. But these things don’t make them right.

There are some academics who can’t see a consensus without revolting against it. And the truth is that the academics will be fine under Brexit. Their jobs are secure. They will go on writing books about the mistakes that the rest of the world will always make. As this episode reminds us, foolishness is evenly distributed between the clever and the not-so-clever.

A reasonable person has to accept that Brexit may happen and that, if it does, life will go on. However, that does not justify or excuse Brexit. There are serious material and domestic political reasons for opposing it – the loss of jobs, higher-priced imports, weakened safeguards at work and elsewhere. But there is also a bigger picture. That bigger picture is the importance of liberal democracy’s ability to play the long global game.

Liberal democracy has a fight on its hands in the 21st century. It has to maintain the place of rights, freedom, openness and coexistence in a world increasingly marked by nationalism, religious sectarianism, criminal greed and arms proliferation, all amid a changing global balance driven by the rise of Chinese power and the decline of American moral authority. We have to hang in there.

Brexit brings nothing at all to this long game. It only undermines it. Our foreign friends see this from their vantage points. We also need to see it from ours. For Britain to do its bit in the world, Brexit must be softened and eventually reversed. It may take time. But we are in a long game.