A conspiracist is someone who believes every problsm in the world is a result of a (non-existent) conspiracy - and most of them are impossibly complex, i.e., remote-controlled airplanes, explosives in the WTC, thousands of traitors planning it and pulling it off perfectly, disappearing, and none of them ever saying a word for the rest of their lives.
Among the many problems of the conspiracist is that all unwittingly engage in the fallacy of post hoc, ergo propter hoc: because possible conspiracies do exist (a few people getting together to kill Jimmy Hoffa), therefore impossible ones exist (the 9-11 Truthers).
Another problem none of them realize they have is that conspiracies are determined by whether or not the politician is Republican or Democrat.
An example: if it had been Richard Nixon in that limousine instead of John Kennedy, there would no belief in a conspiracy to kill him. Only Democrats are the victims of conspiracies, while Republicans are the perpetrators.
If it had been Nixon killed, many people would have cheered, making jokes about why it took Oswald three shots to kill him. Never mind the fact Nixon was a far better man than Kennedy -- both just happened to be lousy Presidents. Nixon was an unattrative man with a ski-jump nose and a sweaty upper lip. Kennedy, on the other hand, was a handsome, charismatic, popular man.
Need more proof? When Squeaky Fromme tried to kill Ford, not a word about conspiracy. Why? Republican. When John Hickley did shoot Reagan, again, not a word about conspiracies. Why? Again, Republican.
Had 9-11 happened on Clinton's watch, there would be no Truther movement, because no one would believe that Clinton, even though he is a cracker white-trash serial rapist who should have gotten life in prison, would do such a terrible thing to the U.S. -- because he is a handsome, charismatic, popular man.
Bush, on the other hand, is an unpleasant, unattractive, psychologically fragile dry drunk with beady little eyes...and a Republican. And there is not one word (and there never will be) that Clinton ws part of the 9-11 "conspiracy." But Bush? Of course.
In the last 50 years, one Democrat killed -- he was the victim of a conpiracy! Two attempts on Republicans -- not a word. 9-11 happened on a Republican's watch -- he was the perpetrator.
Just watch -- if anything happens on Obama's watch, there will be not one word about a conspiracy, because Obama is a charismatic, popular man.