I have a favorite bumper sticker. I haven’t seen it for a while, but it says:
“Just Because I’m Paranoid Doesn’t Mean They Aren’t Out to Get Me”
A “conspiracy theory” is generally defined as “a theory that explains an event or set of circumstances as the result of a secret plot by usually powerful conspirators”. A group of people conspire to make something happen. The group can be a political group, or an ethnic group, or even a family group (certain rich dynasties seem to attract conspiracy theories).
Just as in the bumper sticker above, it is difficult to disprove a conspiracy theory. On the other hand, there are usually “holes” in the chain of “evidence” that connects the group to the event. (That doesn’t matter to those who want to believe the theory.)
These holes include circular reasoning (X happens because of Y, Y happens because of A, A happens because or X). They include lack of proof of presence (we don’t know where Ms. Q was at the time, perhaps they were at THIS location doing that). Motivation is often connected to pre-conceived notions as to character or beliefs about what they are trying to do in more general terms. Denials cannot be true because the denials come from “the guilty parties”.
My personal feeling is that the most distinctive aspect of conspiracy theories is reverse reasoning. A person starts at the desired conclusion and the group that they want to tie to that conclusion and then start building “evidence” that connects the two. A good way of recognizing a conspiracy theory is that it usually only talks about the two end-points — the group/people and the event/conclusion. If pressed, some may be able to point to in-between logic which can then be examined. But most people passing along conspiracy theories don’t know of any (if any exists) “evidence” that the endpoints are connected.
If conspiracies never happened then they could all be dismissed without evaluation. They sound crazy so they must be crazy. Back to the above bumper sticker. Conspiracies can happen and we have all heard something of the nature “it must be true, I could never make up something that crazy”. The aspect of being unbelievable makes them more believable simply because life is unpredictable and events happen that we could never explain.
So, if a conspiracy theory MIGHT be true, why does it matter? Primarily because, most of the time, it is usually NOT true. As someone (among many) who tends to make up statistics when I don’t have anything solid at hand — I would say that 98% of conspiracy theories are not true. The exact number is likely to be wrong but it is certainly a high percentage. The reason this is so is due to the reverse logic — building up a “case” based on what we want. There are so many possible paths that can be taken, from the end to the supposed decision starting point, that having the entire logic chain being correct just fades away into unlikelihood.
And believing when it isn’t true can cause a lot of damage. It can also cause violent action based on the incorrect assumptions. Since conspiracy theories tie specific groups or individuals to the conclusion, it can be very tempting for those who have chosen to believe them to follow the short-term approach of eliminating that group or individual.
What about those few cases where it is true? Well, as the saying goes — “a broken clock is right twice a day”. If a conspiracy theory is true then the same conclusions and connections can be achieved via a more direct investigation.