Britain is a European country. The question confronting its people in the referendum tomorrow is only about the kind of European country it will be. Will it be on the margins of Europe or will it exercise influence appropriate to its history and size?

The referendum campaign has been dismal. But that does not make it unimportant. On the contrary, a decision to leave would damage not only the UK but also Europe, the west and the world.

In making this decision, rational voters must understand the asymmetry in the decision. As a sovereign country, the UK can change a decision to remain. But it cannot change a decision to exit.

Yet such cold calculations do not win hearts. Those in favour of leaving argue that their opponents do not believe sufficiently in the UK. I think we should remain because I believe in it so much. As a child of grateful refugees from Hitler, I believe that the quiet decency, democratic traditions and liberalism of the British offers something irreplaceable to Europe.

The democratic Europe of today owes immeasurably to British politics, British values and British courage. Britain would lose hugely if it cut itself off from the continent. But so, too, would the latter. Yet the arguments of those in favour of leaving are not worthless. They are rather exaggerated or incomplete.

The very fact that the UK is able to hold this referendum demonstrates that it remains sovereign. The repository of legitimate authority is and will remain a duly elected parliament. The question is rather how to exercise power effectively and democratically.

Those in favour of leaving argue that all decisions that affect the British people are accountable to a democratically elected parliament.

A second’s thought reveals this is absurd. A huge proportion of the decisions that affect the British are made by decision makers over whom voters have no control because they are foreign.

To affect such decisions, parliament must delegate powers to international bodies, in order to increase its influence on them. Again, the scale of immigration has been a surprise. Its benefits have been exaggerated. But so, too, have its costs. We should have agreed lengthier transitional controls and safeguard arrangements on internal migration. We could also have managed immigration far better.

Xenophobia

Nevertheless, it is crucial to note that net immigration from non-EU countries is cumulatively far bigger than that from the EU; and, in all probability, the latter will now decline. Above all, nothing can justify the xenophobia and outright lies from Brexiters on this topic. Those liberals in the Leave camp should feel ashamed of the company they keep.

Then there is the argument that the EU economy is not doing well. The extension of the euro to all its present members was indeed a huge mistake. But the idea that the UK can shield itself from the failures of the EU by leaving is also absurd. The EU will remain our biggest economic partner whether in or out.

Both long- and short-term economic effects will fall somewhere between bad and disastrous. Economists on the Leave side have failed to dent the virtual unanimity of expert opinion. The response of the Leave campaign has been to denigrate the notion of expertise. That is silly enough. Far worse, it has not even pretended to have a coherent post-referendum plan.

The only certainty is years of uncertainty – and not only for the UK. Why it makes sense for a country scarred by a huge financial crisis to take a leap into this abyss is beyond any sane person.

Yet it would be absurdly narrow-minded to focus only on what this means for the UK. It is far more important than that.

Despicably, Boris Johnson compared the EU with Hitler's Reich. The truth is the precise opposite: the EU has played a huge role in spreading democracy across the continent. It is an attempt to entrench prosperity and cement co-operation among nations. It is imperfect. But never before has Europe been so prosperous and so peaceful. The challenge is to make it better. That is why British engagement remains so important. Without it, the effectiveness of the EU, even its survival, might come into question. Alternatively, it might unite as a single entity over which the UK would then have no influence. Either outcome would surely be a strategic nightmare for the UK.

The UK is far more than a hugely important participant in the EU. As a great European power and mother country of the English-speaking world, it is the hinge between the two. UK withdrawal would herald western weakness and global disarray. This is why all the UK’s friends favour its membership.

Nobody can fail to recognise the profound distrust of elites that animates the Brexit campaign. But xenophobic populism is never the right answer. At the end of this wearying campaign, the voters must realise who they are and the weight of what they must decide. Yes, the British might well survive on their own. But why should they try? Britain can be far better than that. Let it choose engagement. Let it choose Europe.

– (Copyright Financial Times Limited 2016)