As a result, they are attracting an increasing volume of foreign investment and are consistently achieving higher growth rates than the old members. A rational West European policy would be to leave well alone and let these dynamic economies be the Irelands of the East. Whether large-scale East-West migration would be economically good or bad is a moot point, but it is also an academic one since it seems unlikely to happen. According to forecasts published this year by the Institute for Public Policy Research, migration to “Old Europe” from the new members will amount to between 3.2 million to 4.5 million over 25 years, increasing the population by 1 per cent. In recent months, newspapers like the Daily Mail have worked their readers into a frenzy on this score. That explains why in only one year of the past 10, EU GDP growth has been higher than that of the US.But the third, and biggest, problem facing the EU is that it is a union of senescent societies.

By 2050, according to the United Nations, the median age will be above 40 in all pre-enlargement EU members countries and above 50 in Austria, Greece, Italy and Spain. In these countries, about one in three citizens will be 65 or over. When Donald Rumsfeld spoke scathingly about “Old Europe” last year, he didn’t know how right he was.It is not immediately obvious why acquiring 10 poor countries – some of which (notably Latvia) are a lot poorer than the old members – should help the EU close this widening economic transatlantic gap.There are those in Britain who fear that enlargement will open Western Europe to the proverbial “flood” of economic immigrants. But many Americans are confident that the gap between their economy and the European economy can only widen in the years ahead. Here’s why.First, European productivity growth has, for the first time in the post-war, period, been below that of the US since the mid-1990s. Second, Europeans are, for a variety of reasons, working a lot less than Americans.

Unemployment is higher; the labour participation rate is lower; above all, working hours are shorter. In the early 1970s, the Germans and French worked about as many hours per year as their US counterparts. Since then, Americans have grown more industrious – working nearly 2,000 hours per year – while Europeans have taken longer holidays and had shorter working days. Today the average Frenchman aged between 15 and 64 works around 35 per cent less, in hours, than the average American. Depending on how you measure total output – particularly how you adjust for changing exchange rates – that keeps EU and US gross domestic product within sight of one another.

They measure it in terms of economics and technology – especially military technology. And by those measures, it is far from clear that enlargement will significantly help the EU.For in the eyes of Americans, Europeans are not merely military wimps (though the surrender monkeys eat tapas rather than cheese these days). Americans do not measure power in terms of territory or demography. In 2002 Robert Kagan proclaimed that Americans were from Mars and Europeans from Venus. He forgot to add that, in economic terms, Europeans are from Saturn – the god who, in ancient mythology, represented old age – while Americans are from Mercury – the god of high-speed communications.Because the new member states are relatively poor – their average per capita gross domestic product is less than half that of the old EU average – enlargement has only a minor impact on aggregate EU output, raising it by little more than 4 per cent. EU membership is a powerful incentive for political good behaviour.Why then does the US seem unworried by European enlargement? Why do so few American analysts share the anxiety of Charles Kupchan of Georgetown University that the EU is “an emerging pole, dividing the West into American and European halves”? After all, any other political entity that trebled in size in just over three decades would surely set the alarm bells ringing in Washington The answer is simple. Western Europe also has some large moral debts to countries such as the Czech Republic, Slovakia and Poland that go back further than the Cold War – to the dark years of 1938 and 1939.Moreover, the world has reason to celebrate the integration of such countries into an institution that explicitly stands for democracy.