A conspiracy theory is an attempt to explain an event by hypothesizing that the event was caused by a group operating behind the scenes.
There have been innumerable threads on FreeRepublic. A partial list of the more significant subjects would include Mena, Bill Clinton, Hillary Clinton, Truthers, Birthers, various Elections, Waco, OKC Bombing, Timothy McVeigh, Flight 800, Y2K, etc.
Any large group will include a fairly significant percentage that shares a belief that some critical event was caused/covered up by a secret group. Some studies have indicated that the percentage is fairly constant across the political spectrum. Only subject and details of the conspiracy vary. Rather interestingly, the belief in conspiracy theories tends to be positively correlated to education.
For example, when Clinton (or Obama) was/is President, a significant percentage of the right believes they are out to destroy the country, dismantle the constitution, and out to dominate the world. A very similar percentage of the left believed that Bush41 was out to destroy the country, dismantle the constitution, and dominate the world. BTW, this paragraph should not be construed to read that I believe or disbelieve either of these, only that I find it fascinating that both the left and the right and in similar numbers believe the same things about each other.
If you want to do some research or verify some of the above, try reading “Voodoo Histories: The Role of the Conspiracy Theory in Shaping Modern History” by David Aaronovitch.
Do you think that calling 0bama a marxist is a “consipiracy theory?”