There's a difference between real-life factual conspiracies and paranoid conspiracy theories. That difference tends to lie primarily in the scale, scope and duration of the conspiracy. Real life conspiracies tend to be small (just a few people involved), with limited and defined goals and take place over a fixed amount of time. That's why assessing those three factors in regards to any conspiracy theory is a handy shorthand to ascertaining the plausibility of the particular conspiracy theory. Of course there's a significant gray area and the exact point at which plausibility transitions into implausibility is hard to say. Can 2 people pull off a conspiracy? Sure. Can 10? Probably. 100? Maybe. 1,000? Almost definitely not.
But when skeptics talk about paranoid conspiracy theories what we're really talking about is not specific theories, except to debunk them. Instead, what we really mean is what has become known as conspiracism in recent times. It's Hofstadter's famous "paranoid style" (read Hofstadter's 1964 essay
The Paranoid Style In American Politics -- you might not agree with Hofstadter, but you should know what he says). It's a fixed, persistent worldview that almost all history and current events can be explained by conspiracy, by covert groups plotting for power in secret to the detriment of the "good" or the "righteous". For the conspiracist, this is the only historiographic tool they bring to the table. Institutional analysis, power structure analysis, class, economics, geography, chaos theory, sociobiology, social psychology... They're all out the window. For the conspiracist, all that matters is "Cui bono?" It's a grossly over-simplified view of the world and often leads to inaccurate conslusions.
Worse still, is that the conspiracist's belief that conspiracy is all one needs to explain the state of human affairs is so overwhelming, the desire for confirmation of that view so great, that not only are facts ignored, but spurious details are often constructed. Indeed, many times over people holding the conspiracist worldview have chosen to interpret fiction as fact. This includes some in the 9/11 Truth movement who view the Lone Gunmen pilot as a coded warning from those with inside information, and the poisonous persistence of
The Protocols. David Icke's reptoid overlords are just the latest incarnation of Edward "
It was a dark and stormy night" Bulwer-Lytton's 1870 novel
The Coming Race.
So it's not that skeptics don't recognize the existence of conspiracies. We do, and we know they have played a powerful role in history. And the unprecedented in American history resort to secrecy by the Bush administration in domestic affairs as well as foreign does not give anyone confidence that elements of the Bush administration
aren't conspiring for monetary and political advantage. It's just that skeptics recognize the limitedness of the petty conspiracy and consider its' role in context with other psychological, social, political, technological and economic forces at play, as well as the interplay between those forces. Additionally, we're given pause by the function of paranoid conspiracy theories as a narrative form of scapegoating (c.f.
Berlet's Conspiracism As A Flawed Worldview). All too frequently, and with frightening speed, paranoid conspiracy theories can gain ground in the wider population and embedded in those paranoid fantasies are bigoted memes that are often used to justify persecution of religious, ethnic or racial groups. In so far as The Protocols inspired Hitler, the Holocaust is a prime example of a paranoid conspiracy theory translated into a moral panic and ending in atrocity.
So really skeptics should probably be more precise in their language when talking about paranoid conspiracy theories and perhaps use the term conspiracist theories instead to distinguish from factual conspiracies. Of course, for the dyed-in-the-wool conspiracist, none of the above will matter and any attempts toward precision will be unappreciated because anyone who counters their paranoid fantasies, no matter how polite, is obviously a disinformation agent shilling for the puppet masters.