There are two reasons why the economic argument for British entry into the euro is fallacious. The first is that it is utterly speculative and rhetorical. The second is that it is irrelevant.
Even if there were no other considerations affecting British entry (and the Government and its apologists like to pretend there are not), the economic case is implausible. In a free-market economy, having one currency as the medium of exchange rather than another will make little odds for the demand for British goods, or the creation of wealth here. Without centralised planning, such things are entirely unpredictable.
In any case, the two European economies most like ours - France's and Germany's - have had deeply disappointing experiences since entering the euro nearly 18 months ago. Why should things be different for us? It may be that Gordon Brown and his advisers genuinely believe there are economic reasons that dictate that we should not yet take part in this project. It may even be (though this is far more unlikely) that they have an open mind on the subject, and think that the possibility of our joining might be reviewed soon.
I suspect Mr Brown, who wants to be Prime Minister, would like some power to exercise if and when he is. He knows he will have far less should Britain have entered the euro by then. This brings us to the real issue.
If we enter the euro we do not merely lose the readily ridiculed commodity known as sovereignty. We lose a substantial chunk of our democracy. At the moment, if a Government pursues an economic policy inimical to the interests of the British people, or unpopular with them, they have in the short term a simple remedy. They can elect a different party to govern with a different policy. However, should we enter the euro, that remedy will no longer be available. Nobody will vote for the people in Frankfurt who set the interest rate, and the inflation target that governs it. If that rate causes hardship because it is wrong for a particular subsection of the European economic unit (as it has been in Germany, for example), then tough. Changing a national government - unless the replacement supports the withdrawal from the currency union or the EU - will make no difference. The economy, under the euro, is deemed to be outside politics; or at least outside democratic politics. It is no wonder Mr Blair and his acolytes are so enthusiastic about this aspect of the project. They don't like the people, with all their crude prejudices and unmetropolitan attitudes, dabbling in matters they feel should only concern the governing class. For opportunistic reasons, they long since promised a referendum on whether we enter the euro, a promise they now regret.
They will not, of course, offer one on the even further-reaching prospect of a European constitution, because that potential surrender of democratic rights would be even more offensive to the British people than the euro already is. That is why the newspaper for which I write, the Daily Mail, has offered the public the chance to participate in an unofficial plebiscite this Thursday. Newspapers are used to being the opposition in this country. When they have to start offering to perform some of the fundamental functions of government as well, aspects of that government have reached a ludicrous state.
The Government dares not acknowledge or properly debate the constitutional argument because it fears what would emerge. If a nation is being undermined by a wrong-headed economic policy, and its people are suffering, and voting can change nothing, then what happens? Will people sullenly resign themselves to that suffering, or will they riot? If they riot, will not the rest of us protest that such a course ought to have been utterly unnecessary, had the democratic safeguards for such eventualities not been removed?
We still have a concept of something called "the national interest". It is a phrase used, hypocritically, by the Prime Minister and his friends all the time. But entry to the euro means there is no longer such a thing, in the economic sense, as "the national interest". There is instead something called the European interest, and politicians who believe the British electorate gives a stuff about that now, or will give a stuff about it at any time in the foreseeable future, presumably also believe the Moon is made of Roquefort. Without our own currency we might, geographically, survive as a nation, with a defined "interest". We will not, though, survive as one democratically. Nor will the "interest" be able to be served. We will be at the mercy of forces with no care for this country or its people in isolation from the rest of Europe. Those forces will not be democratically elected or accountable, and will have the potential to act capriciously as a result.
Internationalists might applaud the end of the national interest, and that is an honourable (though in my view entirely masochistic) position. If they applaud the erosion of democracy and accountability, they are simply supporting the contention that the Europe being created is simply a more capitalist version of the Soviet Union.
They may be happy to have that on their consciences. I, and millions of others in this country, are not.
Simon Heffer is a columnist for the 'Daily Mail'.