Philip Hensher: This common coinage could be the undoing of all that unites Europe

What makes us European? Is it our shared culture? Is it our shared system of values? Or is it our money?

What happens when a Spaniard and a Swede bump into each other, assuming they can find a common language? Do they agree to spend their money together? See that they're living in the same sort of mental space where people's lives and views are respected? Or just discover that they both just love German techno?

Or are they forever separated by the fact that they were born in different countries? It's easy to think, as the European monetary project falters, that the things which bind Europeans together are less powerful than the ties of the nation state. It is certainly the case that, whenever a problem emerges, national media and politicians are quick to isolate domestic concerns and values from the concerns and values of the whole union.

This was apparent in a small, malevolent way with the outbreak of E.coli in Germany in June. Before the source was identified as locally grown bean sprouts, speculation pointed to Spanish vegetables. Only outside the EU, as Russia banned imports, did anyone seem to think of the source as European vegetables. Within the EU, the thinking was lucidly national: for the Germans, the Spanish were the source of poison; for the Spanish, the Germans were the source of national calumny.

That solved itself without lasting effects. But the disastrous state of European finances has produced national divisions which will last for generations. One patched-up solution to the Greek crisis came this week; others will no doubt follow. The interesting thing is that, while a European economy appears a single, committed project when things are on the up, when problems emerge, the economies become national once more.

A shared coinage suddenly seems a weak bond between people who don't have a language in common. What began as a brave partnership starts to look like an overambitious dog-walker's outing, taking a Great Dane, a Rottweiler and a chihuahua out on the same lead. Hundreds of billions of euros have been provided to prop up the Greek economy, in one conciliatory phase after another, like a five-year-old's tea. But the apparent willingness to hand over any amount of money has led to a distinct lack of Europe-wide brotherhood. John Lanchester summed it up well in his phrasing of a question increasingly asked in Germany: "Why [should] Germans work until 69 to fund the retirement of Greek public-sector workers who (supposedly) knock off at 55?"

Germans have, of course, been through this once in recent years. The events which led the former citizens of West Germany to labour in order to restructure the equally catastrophic economy of the former East were accepted with less complaint, as a national duty. It seems obvious that there is no comparable sense of European duty which would lead them, and us, to prop up the failing economies of our European partners. Is there, in reality, any European partnership at all?

There are three aspects to the European project. The first, of ultimate monetary union, appears fragile and with a doubtful future. The second is cultural, where de facto union, the free flow of ideas and ways of living, has been in process for centuries. The third is political in the broadest sense: the establishment of a shared political culture, of assumptions about rights, duties and democracy. That, too, has been a great success. From the point of view of the rest of the world, the political unity of European thinking has never been stronger.

That sounds unlikely, but think of the public values that are universal within Europe. Freedom of expression; legal rights; democracy; equality between the sexes; racial equality; freedom from torture and capital punishment. Some of these are better carried out than others, and better observed in some parts of Europe than in others, but they are all enshrined universally, and all originate in liberal European thinking. These things bind us together.

They are, too, values which precede the European Union by centuries, and which were propagated across Europe as easily as cultural phenomena. When Samuel Johnson remarked that Frederick II of Prussia was the only great king in Europe, or Voltaire wrote his admiring book on English political institutions and public life, these ideals were travelling from one end of Europe to another in almost imperceptible steps, like Brownian motion.

And it shouldn't be forgotten that one of the primary motivations behind the euro project was to insulate and protect liberal political values. If countries were bonded through their currencies, there could be no danger of falling back into the illiberal public policies. Germany could be saved from itself; a Le Pen could, if the worst happened, be led by the nose.

Later, with the fall of the Berlin Wall, the prospect of euro membership could be held out before the countries of the New Europe, to lead them away from Soviet values. Just how potent is that promise? Well, Poland abolished the death penalty in 1998; Romania decriminalised homosexuality in 1994. And as for faith in the monetary mechanism to deliver liberal freedoms, Estonia joined the euro as recently as last January, with hardly a backward glance.

The discomfiting thing for the EU institutions now, however, is that European freedoms managed to spread and solidify, in the event, without any apparent help from a single currency. It was a word-of-mouth thing. Similarly, culture disseminated itself from Lisbon to the borders of the old Soviet Union, enabled by the dropping of barriers to trade and travel, but also driven by people's desire to try the new things they were suddenly exposed to, to dance to a hit record, read that new book that everyone is talking about.

Food is much less locally distinctive now than it was 30 years ago, for both good and bad; give or take a local enthusiasm for the interval of the augmented second, so is music. In two out of three areas, Europe has achieved a unity and brotherhood beyond the wildest dreams of a generation ago. Some of that is down to the EU, the free transport of goods and services and, especially, the Schengen treaty. (Who would have dreamt, in 1989, that within a very few years you could travel from Spain to Hungary without showing your passport?) The spread and agreement on values might have happened anyway.

With the ill-tempered arguments among political leaders and the resentments over who pays for the Greek default, it might seem as if the mechanism intended to bring about social unity will be the unwitting means of undoing it. The euro is the product of a politician's will; the force which, increasingly, gives an Italian and a Dane something in common is just something that has happened, like a change in the weather. And we all know which of the two is more powerful. But it is also true that the future of the EU lies in a million small personal encounters. If those, too, start to be inflected by debt and obligation, then the whole project is in trouble.