Conspiracy theories are all wrong for one basic reason. By this statement I refer not to the limits of verbiage. No, conspiracy theories are wrong because they all assume the human intellectual capacity is greater than it actually is. To pull off a conspiracy involving the twin towers is one example---- nobody is smart enough to set that up. For this to be possible you have to estimate the intelligence of engineers as higher than it is, and then you would have to estimate the conspirators as a lot smarter than the engineers are. There is nobody on this planet, who knew in the moments before the plane hit a tower, that the tower would then collapse.
Another example-- the assassination of the archduke in Sarajevo. That succeeded because of an accident, the hit did not take place on the scheduled route.
Only in a world without contingency, a locked in jigsaw of comprehensible cause and effect, could the typical conspiracy succeed, but that is not the way our universe is.
Of course there are many physical scientists who assume this picture-- everything colliding in ironclad causal interconnections--IS the way the world operates, and we just have not yet found out all the rules. They assume that all dim areas will be eliminated eventually, probably sooner than later.
Which brings me to UFOs, etc, nicely drawn on the blackboard in the picture below which I got from Spiked Review. The modern apprehension about life in outer space, the amounts spent on discovering that possibility, the generally gloomy visualizations of the possibilities of encounters with such, is actually a perspective that dates to before man's grasp of his reasoning capabilities even began. These views expressed by the spokesfolks for natural science, are the same as primitive man's apprehension that he is in a huge and transitory world and even the higher powers are fickle.
One word for the situation is that the complexity of which we are a part, is greater than man can comprehend. We succeed by knowing the boundaries as we press on them. Conspiracy theories function to hide man's ignorance.
Here is supplementary reading--- I didn't but you might like to. It provided me with a perch on which to sketch out some ideas about conspiracies. No need to read beyond the headlines, but if you insist, here is one.
FRANK FUREDI The politics of the hidden agenda
A short essay from 2009 on how conspiracy theorising has now become respectable.