A conspiracy theory is a paranoia induced collection of explanations that are created by usually anti-government or anti-authoritarian wackos that want the world to conform to their fictional universe.
In most cases these "theories" are often intended to make a large scale event become an attack by the grand cabal of evil men trying to rule the world from the shadows. If there is a important event in history expect one of these grand contrived theories to appear as an alternator explanation for the simpler real reason for the event. Remember it doesn't matter to them if there is a real conspiracy behind the event that is openly visible it has to THEIR conspiracy behind that actions. Conspiracy Theorists in general have the attitude that they are the only smart people who can actually see the world for what it really is. It doesn't matter to a Conspiracy Theorist if their explanations contradict each other since only the end result matters to them. They also tend to toss as many claims out as possible repeating themselves constantly making refuting them extremely difficult. If you fail to address even one of their claims they will latch onto that to dismiss the rest of your argument.
- FDR planned Pearl Harbor.
- We never landed on the Moon.
- 9/11 was an inside job.
- Global Warming
- JFK was killed by the CIA/NWO/insert group here.