It is notoriously difficult to prove a negative. At what point can you be sure that something does not in fact exist? For example, if I lose my glasses and begin to search for them in my apartment, when do I abandon the search and conclude: I must have left them at the office? Is it when I have checked all the pockets in my wardrobe? Looked under all the cushions in the apartment?

So it goes with the search for weapons of mass destruction in Iraq. Certainty may not come for a long time. Let’s add that it was entirely reasonable to argue–though some disagreed–that Saddam Hussein possessed such weapons. After all, it’s a matter of record that he had them before the Gulf War, and the United Nations inspectors sent in after the war to destroy them reported that some materials were still unaccounted for.

But questions of fact cannot be resolved by thinking. Evidence is required. And if the evidence is used to justify a war, then it must be both unchallengeable and readily producible. Before the war, the Bush Administration stated on dozens of occasions and in the most unequivocal terms that it had such evidence. Now–nine weeks after the end of Saddam’s regime–it is clear that no evidence of the required quality existed. The public trust was abused. The world was deceived. That the unequivocal evidence was missing before the war will remain a fact even if, somewhere down the road, weapons of mass destruction are found. “We know where they are,” Defense Secretary Donald Rumsfeld said. But he did not know. How could he, when the intelligence agency of his own Defense Department was stating that there was “no reliable information on whether Iraq is producing and stockpiling chemical weapons, or where Iraq has–or will–establish its chemical warfare agent production facilities.” The war was fought on false premises. One might hope that some of the war’s supporters would now reconsider their position. I know of no such case. Instead, we have been presented with an entire bestiary of excuses–ones so inventive, it has some interest in its own right.

1. The UN Said So. Columnist Robert Kagan of the Washington Post has written an almost touchingly plaintive column listing all those who credited the mistake, as if widespread belief could make falsehood true. Among those mentioned are not only President Clinton and other Clinton officials but, of all people, the leaders of Germany and France–temporarily de-demonized for the purpose. Even the head of the UN inspection team, Hans Blix, is cited. In fact, of course, Blix never stated, as the Bush Administration did, that there were weapons of mass destruction but only that there was some evidence that there might be weapons of mass destruction. The crux of the argument was whether the inspectors should be given more time to resolve doubt into certainty–one way or another. The Administration itself has joined in the unexpected rehabilitation of the UN. The White House communications director, Dan Bartlett, has said there is proof of an Iraqi weapons of mass destruction program because “the UN Security Council passed a resolution that confirmed it.”

2. The War Was Really About Something Else. There are innumerable variations on this theme. Senator John McCain, who once toured the country in a bus called The Straight Talk Express, now says, “The American people support what the President did, whether we find those weapons or not, and they did so the day they saw 9- and 10-year-old boys coming out of a prison in Baghdad.” It seems that the straight talk McCain required of candidates is not needed by Presidents. None other than arch-hawk Deputy Defense Secretary Paul Wolfowitz has said the choice of the WMD justification had “a lot to do with the US government bureaucracy, we settled on the one issue that everyone could agree on, which was weapons of mass destruction as the core reason.”

The idea that the war was really about something else all along has been especially popular among its more liberal supporters. Former Nation columnist Christopher Hitchens reserves “the right” to be for the war for reasons other than those given by the Administration. Thomas Friedman, who, it must be said, never did express worry about Iraqi weapons of mass destruction and instead supported the war as a way to “democratize” the Middle East, confesses, “I have to admit that I’ve always been fighting my own war in Iraq.” The trouble, of course, is that Hitchens and Friedman are not deciding policy. The world doesn’t get the war as described in their columns; it gets the real war the Administration actually is fighting. They are supporting a phantasm.

3. They Didn’t Really Mean It. In an editorial dismissing the importance of the evidentiary fiasco, the Washington Post admits, “Some of the claims tossed off by Vice President Cheney and other senior officials in the heat of the debate appear unlikely to be borne out.” Very likely the Vice President of the United States just got carried away when, in a prepared speech on August 26 to the Veterans of Foreign Wars, he announced, “Simply stated, there is no doubt that Saddam Hussein has weapons of mass destruction.” And perhaps the President was merely hot under the collar when he used the “no doubt” language in his last press conference before the launch of the war.

4. We’ve Already “Found the Weapons of Mass Destruction.” This from the President himself, in a statement made in Poland, referring to trailers found in Iraq that may or may not have been built to produce biological weapons. But soon he seemed to take it back, stating at the military base in Doha, Qatar, “We’re on the look” for the weapons. A few days after that, he shifted again: “I am absolutely convinced with time we’ll find out they did have a weapons program.” As things stood at that moment according to the President, his Administration had (1) found weapons of mass destruction but (2) not yet found a weapons of mass destruction program. The facts on the ground showed nearly the opposite: inconclusive evidence of a program (the trailers) but no weapons. So “programs” and “weapons” were now the same and our government had at the same time found and not found both. The President seemed bent on demonstrating, publicly and swiftly, the factual illiteracy that his Administration demonstrated secretly and in slow motion as it took the United States to war.