The US Department of Defence last week released videos of Flight 77 being flown into the Pentagon on September 11, 2001. The footage was obtained by Judicial Watch, who filed a Freedom of Information Act request. Tom Fitton, president of Judicial Watch, said: "Finally, we hope that this video will put to rest the conspiracy theories involving American Airlines flight 77."
Fat chance of that; neither video shows anything conclusive. In both tapes, a blurred shape is visible for a second before the Pentagon is engulfed in flames. The shape could easily be a missile, as the conspiracy theorists claim, or it could be what it, in fact, is: an airliner.
The debate about 'what really happened' has been going on since September 12, 2001, but gained intensity with the Loose Change documentary, which has spread across the internet.
Loose Change makes a series of claims, from the seemingly reasonable – the US government knew more about Sept 11 than they let on – to the downright bizarre – the planes which flew into the WTC had missiles underneath them, which they fired moments before impact.
Much of it can be debunked simply by thinking about it. If you're flying an airliner into a building, why on earth would it need to fire a missile into the building as well? Having flown two airliners into the largest building in the world, why would you need to set explosives to demolish the building?
For some of the claims, however, a little more expertise is helpful.
The trouble is you can't argue with conspiracy theorists. Like the religious, they simply shift the goalposts when confronted with an argument that they can't refute. For religious people, the standard escape clause is "it's a matter of faith". For conspiracy theorists, it's "how convenient".
Thus… explanation: "The World Trade Centre collapsed because the structural integrity of the steel was compromised in the fire." response: "How very convenient for the government."
explanation: "Lax airport security allowed the hijackers to smuggle boxcutters onto the plane" response: "How very convenient for the government."
explanation: "Many WTC workers were late for work that morning because Monday Night Football had overrun." response: "How very convenient for the government." …and so on.
It's pretty easy to see that conspiracy theorists would have had a field day whatever the outcome of September 11. Suppose the hijackers had been thwarted at the airport: what a convenient way for the government to launch a 'war on terror' without bloodshed.
No matter what happens, it's always possible for a conspiracy theorist to find 'evidence' of a hidden agenda. Indeed, they often don't need evidence, the very lack of it constitutes proof for these people.
If they can pose a question that can't be answered, this somehow counts as proof of their version of events. Offer an answer and you're back in "how convenient" territory again.
Amusingly, conspiracy theorists aren't even safe from each other. The Project for the Exposure of Hidden Institutions has provided one of the most thorough debunkings of Loose Change, while What Really Happened argues that the US government wants you to believe there was no plane at the Pentagon because it hides the involvement of an Israeli spy ring.
There are many unanswered questions around Sept 11, some of them result from the sheer chaos wrought by the attacks and others are the fault of the US government itself, which has exploited the attacks to justify its policy aims and withheld information to protect incompetents within its ranks.
What I hate most about conspiracy theorists is that their nonsense gets in the way of holding governments accountable for real outrages, such as those above. They focus on deranged fantasies rather than face the hard slog of following paper trails and examining small print, which is the way real government conspiracies are exposed.
For all that they like to portray themselves as people who are not taken in by propaganda, as mavericks that are prepared to think the unthinkable, they are actually a conservative bunch.
They genuinely believe in the power of government, they really think there is an organised global ruling class. It's easier for them to think those things than to contemplate the idea that perhaps unfairness is built into the system, that thousands of tiny acts of selfishness can have major consequences and that sometimes bad things happen to good people.
In the case of Sept 11, there is the patronising dismissal of the level of anger in the Middle East. Surely an event such as this, they argue, could not have been carried out by a few angry Muslims - only a powerful Western government could have done this.
By extension, it seems to me, they absolve the US of its responsibility for the imperialist attitude it has displayed across the world since the end of WWII. It seems symptomatic of a pathetically insular world view.
In my own conspiracy theory, I wonder whether governments actually like having these people around. They are 'useful idiots' whose fevered imaginings distract the media from real outrages.