For many years Britons and Americans have been proud of the quality of their governance. Yet today our politics and government are setting new standards for dysfunction. Rather than stability and global leadership there is confusion.

The US is suffering from a serious inability to legislate. There is a genuine risk of the country defaulting on its debts. Jeb Bush called Donald Trump the “chaos candidate”, but as the American writer Jonathan Rauch has pointed out the Trump candidacy was the product of political chaos – in campaign finance, for example – not its cause.

Meanwhile, Britain is suffering its own governability crisis. Leaving the EU was mis-sold as a quick fix. Now it looks like a decade-long process of unscrambling the eggs of national and European legislation. Ministers cannot even agree among themselves the destination, the route map or the vehicles to get us there.

This transatlantic malaise has a common root: politics based on what you are against, not what you are for. Look at the campaigns against the Affordable Care Act (Obamacare) and against the EU. There is a common trope: the politics of grievance.

Complaints about individual policies became attacks against a whole institutional architecture. There were outright lies in both campaigns. And there was a complete (and effective) refusal to describe, never mind debate, what would replace the status quo.

Healthcare makes up nearly a fifth of the US economy – about $1tn larger than the whole UK economy. Support for Obamacare is growing, dramatically, because the alternative has finally been spelled out. It turns out that populism is popular until it has to make decisions.

In Britain, the implementation of the EU referendum decision has been rash and chaotic. The timing and content has been governed by factions in the Tory party. Our negotiating position is a mystery – even on immigration.

So the fightback against the worst consequences of the referendum has the opportunity and responsibility to get its bearings fast. Recent calls from Stephen Kinnock, Heidi Alexander and William Hague for Britain to embrace the European Economic Area are sensible. Nick Clegg’s point that a reformed Europe centred on the euro implies outer rings which Britain should consider also makes sense.

I never thought I would say this, but the chancellor, Philip Hammond, is also playing a valiant role. The transition he supports is vital. However, a transition postpones a rupture rather than avoiding it. Slow Brexit does not mean soft Brexit. Steve Baker, minister in the department leading the negotiations, has been refreshingly honest in saying the transition period is a “soft landing for a hard Brexit”. We have been warned.

The case against the EU depends on avoiding a discussion of the alternative. It is the equivalent of voting to repeal Obamacare without knowing the replacement. It is a stitch-up. That is one reason it is essential that parliament or the public are given the chance to have a straight vote between EU membership and the negotiated alternative. That is a democratic demand, not just a prudent one.

People say we must respect the referendum. We should. But democracy did not end on 23 June 2016. The referendum will be no excuse if the country is driven off a cliff. MPs are there to exercise judgment. Delegating to Theresa May and David Davis, never mind Boris Johnson and Liam Fox, the settlement of a workable alternative to EU membership is a delusion, not just an abdication.

Brexit is an unparalleled act of economic self-harm. But it was a big mistake to reduce the referendum to this question. The EU represents a vision of society and politics, not just economics. We need to fight on this ground too.

The Europe of Emmanuel Macron and Angela Merkel stands for pluralism, minority rights, the rule of law, international co-operation – and not just a single market. In fact, the real truth about the single market has been lost in translation.

It is not just a market. It is a vision of the good society. Rights (and holidays) for employees, limits on oligopolies, standards for the environment are there to serve the vision. The single market stands against a market society.

This is all the more important in a world where autocratic leadership is on the march. This is not just about China or Russia. The democratic world is itself splitting into authoritarian and pluralist camps. We can see Venezuela has taken a repressive turn. Within the EU, there is a battle to hold Hungary and Poland to their commitments, and Brexit weakens that effort.

And the US is not immune. John Cassidy of the New Yorker has coined the notion of “democratic erosion” – gerrymandered congressional districts, voter suppression and attacks on the media. Half of Republican voters say they would support the decision if President Trump postponed the next election.

The EU is not just a group of neighbouring countries. It is a coalition of democratic states which pledge to advance human rights, the rule of law and democratic rules. That is not a threat to Britain; it is the team we should be in.

So Britain’s choice about its institutional future is not just about pounds and pence. I favour the closest possible relationship with the EU, not only for economic reasons. The EEA does not just make business sense. Europe represents a vital and historic alliance of democracies, founded on the idea that social, economic and political rights go together and that countries best defend them in unison not isolation.

History makes the point. The post-second world war commitments to rights for individuals have their immediate political origins in the Atlantic Charter, agreed between Churchill and Roosevelt in Newfoundland in 1941. It set out the terms of postwar peace – notably human rights, national self-determination and international co-operation. It was called the “birth certificate of the west” by the former German foreign minister Joschka Fischer.

The insight was simple. Globalisation without rules and institutions would not mean more control for ordinary citizens. It would mean less. And less control means more risk to the living standards of those in greatest need. International co-operation was and is a force for social justice and against turbo-capitalism.

President Eisenhower said when you had an insoluble problem, enlarge it. The debate about transitional arrangements and institutional design of our relationship with the EU craves a broader framework. There is nothing more fundamental than the economic, social and political rights that looked like the norm at the end of the cold war. Now they are in retreat. Europe is their bastion. And that is the side we should be on.

David Miliband is president and CEO of the International Rescue Committee, a humanitarian aid, relief and development NGO based in New York. He is writing in a personal capacity