No explosives have been found, no combustible liquids posing as bottles of Fanta have been located, nobody has uncovered even a single do-it-yourself guide to downing a jumbo jet. No flights have been identified as potential targets, none of the 24 arrested people has emerged as the leader of the alleged plot. Such details of the alleged plot as have been leaked are sketchy, sometimes impractical. The Americans are saying one thing, the Brits are saying another. Nobody died; nobody was injured.

None of this is to suggest that there wasn't a plot to blow up aeroplanes. Given the extent to which young Muslims around the world have been radicalised by George And Tony's Bogus Journey in Iraq, and by recent events in Lebanon, it would be a miracle if myriad plots to attack the west weren't under consideration. The security forces, in whatever jurisdiction, deserve the support of the world in trying to prevent such disasters, and if it turns out that what happened in London last week was a successful counterterrorism operation, enormous credit is due to all the people involved.

However, there are enormous grounds for scepticism, not just about last week's operation, but about the conduct of the so-called "war against terrorism" in general. It has been, for the most part, based on breathtaking dishonesty, both about the level of the threat and about the nature of it.

As is widely known now, Bush and Blair lied about the presence of weapons of mass destruction in Iraq, and based a war upon that lie. In the past 13 months, one innocent Brazilian, John Charles De Menezes, was shot dead by British police who had concluded with no evidence at all that he was a terrorist. It's only a few months since British police, "acting on intelligence", invited ITN news cameras to look in on an operation against two men in Forest Gate, London, both of whom turned out to be innocent, and one of whom was shot for his troubles.

'Scepticism is a virtue' used to be the motto of the late US media magazine Brill's Content, and this has never been more true than in the "war against terrorism". No other subject of debate in the world today is pockmarked by such willingness on the part of the public to hand over its critical faculties and believe whatever it is told.

In the days after De Menezes was murdered, many in the British media fell over themselves to congratulate the intelligence services and the police on a job well done. Official sources were quoted without any serious examination of their extraordinary claims. De Menezes was said at one point to have been wearing a 'bully top', which could have concealed a gun, a piece of information which was then used to justify his shooting. But there was no gun, there was no terrorist.

Just about everything we've read and seen, particularly in British newspapers and television channels, over the last few days is coming from such official sources and should therefore be treated with suspicion.

Sky News has been in particularly ludicrous mood, treating the 24 arrests as a kind of test of national mettle, in which the intelligence services compete with the English cricketers to put a summer smile on the faces of the queen's subjects. Any quest for the truth is lost in the search for a hero and for examples of the old British bulldog spirit. Message of the week from Sky and some other English news organisations:

those Muslims don't like it up 'em.

Not that we've been free of nonsense this side of the Irish Sea either.

I'm not a security expert, unlike half the rest of the country, but I am sure from travelling to and from Britain that (until the last few days anyway) security at Dublin airport has been no worse or better than at many of that country's provincial airports.

The idea, therefore, that Ireland represents some sort of weakest link, an easy access point for terrorists wanting to attack Britain, is stretching a point. The notion that a would-be bomber would fly to Dublin from England so that he or she could then fly back to England to do a bit of exploding and bombing is simply not credible. For a start, we're talking about an airport that closed down for a while a few weeks back on the basis of one unattended bag and a Koran. A swarthy Muslim-looking chappie holding a suspicious bottle of Lucozade wouldn't stand a chance.

More seriously, the idea that Dublin airport is a better bet than Leeds/Bradford, Glasgow or Newcastle to launch an attack on England is simply not credible. We might, of course, be a target ourselves, because of our practical support for the Bogus Journey, but that's another story.

Last week, the British authorities upped the ante in the "war against terrorism" because, they say, the terrorists had done the same thing.

They now need to prove to the world that this wasn't another over-reaction, another false dawn, another intervention based on a dodgy intelligence dossier.

In other words, they need charges, they need convictions, they need provable evidence that two dozen men and women were on the verge of carrying out what would been one the most vicious, immoral attacks on innocent people since the United States destroyed Hiroshima and Nagasaki. If they don't achieve that, the leaders of the "war against terrorism" will have been reduced to the status of the boy who cried wolf, forever hyping a danger for their own political, electoral or personal ends.

In the meantime, treat everything you read about the terrorism threat with a healthy dose of cynicism. In these troubled times, scepticism is not just a virtue. It's a duty.