You can't reason someone out of something that he didn't get into by using reason in the first place. That's why it's so difficult to refute conspiracy theories with logic. This is especially relevant given the way that conspiracies spread in the Internet age.
It starts out with a cuckoo theory promoted by crazy people and integrity-free professional con men who pump every conspiracy that comes down the line. The crazy people push the conspiracy theory because they're paranoid and don't understand how the world works while the sleazy hucksters promote it because conspiracies sell on the web. Eventually, as the conspiracy starts to draw a crowd, more imitators pop up and the crazies and flimflam men create a vast web of references to each other.
Meanwhile, the people who know better generally ignore the topic altogether because they don't want to draw attention to it. Unfortunately, that tactic doesn’t work anymore. In the bad old days when there were only a few mainstream "gatekeepers" who controlled the flow of information to the public, it could be successful, but it's a non-functional strategy in the age of New Media.
So, when the average person starts to research a conspiracy theory on the Internet, he finds an endless array of conspiracy websites, all linking back and forth, while the doubters largely remain on the sidelines. After seeing only one side of the story, many people who don’t know any better conclude, "Well, I GUESS this could be real." Next thing you know, 35% of Democrats think George W. Bush was involved in the 9/11 attacks and another 26% aren't sure.
One thing that most people seem to miss is that these conspiracy theorists almost NEVER present any sort of coherent theory. They just ask questions, point out discrepancies, and demand that every single bit of uncertainty be answered to their satisfaction or else, the conspiracy MUST BE true. This is, of course, perfectly ridiculous. No matter what the subject is, there are always disagreements, loose ends, and questions that remain unanswered.
Just to prove that point while I give the Truthers a taste of their own medicine, here are ten questions about the 9/11 conspiracy theories. The next time someone asks you wacky question about the “government conspiracy” behind 9/11, hit him back with a question. Granted, it won't change his mind if he’s a kook, but you just might reach a few of the casual conspiracists who haven't fully embraced the crazy yet.
1) If the United States government was actually behind 9/11, hundreds, thousands, and maybe even ten thousands of people would have to be involved. Do you really believe that many Americans would stay quiet about the murder of 3,000 citizens by our own government?
2) Some Truthers believe a car bomb or a missile hit the Pentagon instead of a plane. So how do they explain the witnesses, like James Robbins, who saw a plane hit the Pentagon?
3) If neither the WTC nor the Pentagon was hit by a plane (and, yes, there are Truthers who believe that), what happened to all the people on the planes?
4) Osama Bin Laden publicly admitted that Al-Qaeda was behind the attacks. How do you explain that if our own government is really behind the attacks?
5) "The 9/11 attacks, or at least parts of those attacks, have been investigated by the 9/11 commission, the CIA, FBI, FAA, FEMA, The National Institute of Standards and Technology, the Senate Select Committee on Intelligence, (and) the House Permanent Select Committee on Intelligence." None of these groups concluded the U.S. government was behind the attacks. So, were they all in on it or are they simply not privy to the same inside information that Alex Jones has?
6) Bizarrely, despite the fact that the WTC was hit by planes, many Truthers claim the buildings were brought down by controlled demolitions. How in the world could that be done without people in the buildings noticing it? Why in the world would they wire the buildings with explosives and THEN fly planes into the buildings? It's not as if terrorists hadn't ever tried to bring down a building with bombs before.
7) Certainly if there was a government conspiracy to target the WTC and Pentagon, Secretary of Defense Donald Rumsfeld would have been involved. Would he really have arranged for a plane (or alternately, depending on how loopy you are, a missile or a car bomb) to be used on the Pentagon while he and undoubtedly his friends and staff, were there?
8) If the Bush Administration was actually behind 9/11, how do you explain the fact that they didn't fake discovering weapons of mass destruction in Iraq? After all, if they were so corrupt that they'd be willing to kill 3000 Americans, surely they wouldn't have any qualms about planting a few WMDs in Iraq.
9) What exactly is the Bush Administration's motive for engineering an attack on Afghanistan supposed to be? Militarily, that was considered to be a high risk, low reward country to invade. If it were just about "popularity" (and historically, that's a very iffy proposition), why not claim that a closer, easier target like Cuba was responsible?
10) If the Bush Administration was really behind 9/11, then surely the Obama Administration must be aware of it by now and they'd have every incentive to reveal it in order to damage the Republican Party. Why haven't they done it? Are they in on it, too?