Somewhere, lying around conquered Iraq, are stocks of mustard gas, nerve gas, anthrax and botulinum toxin, plus numbers of Scud missiles, gas centrifuges for uranium enrichment and mobile biological warfare factories. We know this because the governments of Britain and the US told us, at various times before the invasion, that Saddam Hussein's regime possessed all these weapons. Moreover, we were told that they were capable of mass destruction and that we should be worried, not only about what Saddam might do with them, but even more about their falling into the hands of terrorists.
They have not been found: US troops search high and low, scientists scurry hither and thither, intelligence operatives question (politely, we may be sure) captured Iraqi leaders, Daily Telegraph journalists empty the filing cabinets. But not a grain, not a drop, not a whiff. Perhaps the Iraqis suffer from collective amnesia; perhaps only Saddam and his sons knew where the weapons were kept; perhaps they were all carted off to Syria. Whatever the reasons, is it very naive to suggest that we should now be more worried than ever? If we do not know what has happened to such deadly weapons, or who controls them, why do we sleep so easy in our beds? Why, since the end of the war, have the terrorist alerts and warnings that had so frequently punctuated the period after 11 September 2001 suddenly stopped? Since Saddam and Osama Bin Laden are both still missing, and since we were told that they had forged close links, is it not possible that they are even now sitting in some Arabian cave, with missiles and some thousands of litres of poison gases, plotting a terrible attack? Why is nobody panicking?
These questions are not often asked, partly because a negative is rarely conclusive (as the UN inspectors found before the war) and doesn't make a good headline anyway. We cannot entirely rule out the possibility that Saddam's weapons still pose a threat - and Geoff Hoon, the Defence Secretary, does have a rather odd way of saying that weapons "must be found". But the common-sense view is that they either didn't exist or were destroyed or disabled long ago. After all, documents supporting the claim, made to the UN Security Council, that Iraq tried to buy uranium from Niger have already been exposed as forgeries - and it is likely that senior government figures knew that they were forgeries.
Common sense also suggests that the real reason for the invasion of Iraq was that the US saw an opportunity to strengthen its control, particularly over oil reserves, in a strategically important region. Saddam was attacked not because he posed a danger to anyone, but because his was by far the weakest regime in the Middle East, unpopular with its people and with its neighbours. It is hard to imagine that in late 21st-century A-levels on the causes of the second Gulf war, the examiners would accept any other answer from the candidates. No doubt some marks would be awarded for references to a crusading zeal for liberty and democracy and to a humanitarian mission to rescue people from state murder and torture - but these are not usually regarded as very sophisticated explanations for wars.
The claims about weapons of mass destruction, therefore, emerge as nothing more than a legal fig leaf. The UN Charter contains no provision for a humanitarian or democratic crusade. Perhaps it should. But as things stood, the only conceivable legal pretext for war was that Saddam had breached UN resolutions requiring him to disarm. Much of the public debate before the war - nearly everything said at the UN, for example, or in the House of Commons - was based on what may politely be called an untruth: that, as British and US leaders repeatedly stated, it was in Saddam's hands whether there was a war or not. There could have been an illuminating debate on how best to oppose tyrants; thanks largely to Mr Blair's insistence on legality (which at one stage seemed admirable), there was not. Instead, there was concealment and deception on a scale similar to that which preceded the British and French invasion of Egypt in 1956 - an episode that has more parallels with the 2003 invasion of Iraq than either the US governing class or the British Labour Party (both of which opposed the Suez adventure) would care to admit.
Does it matter? Is the liberation of the Iraqi people not enough? Should we not, as the rhythms of news require, move on? We know that truth is the first casualty of war and that governments lie and dissemble all the time; on this occasion, you could say, the results were reasonably benign. Casualties were relatively light; a loathsome government, without a shred of popular support, was overthrown; people no longer have their fingernails pulled out; the US occupiers may fire a few bullets, but they will not rule with an iron hand.
Yet it does matter. If our leaders misled us so comprehensively on Iraq, and put their hands on their hearts and called God in their aid as they did so, can we trust them on anything? Why should we believe Mr Blair when he tells us that foundation hospitals are not designed to prepare for NHS privatisation? Why should we believe assurances that there are no intentions to invade Syria or Iran?
Functioning democracies, like functioning markets, depend on information. Falsehood corrodes trust and ultimately unhinges our sense of reality; when rulers appear as habitual liars, stories about how Mossad was behind the attacks on the World Trade Center and how extraterrestrials have landed - and all the other paranoid fantasies of green-ink letter-writers - begin to seem plausible. The war is over - official. We should not forget that, on the evidence now available, it was based on a profound dishonesty.