Everybody knows that conspiracy theories are always totally barking, and anyone who proposes one can be safely ignored, or laughed at. As a rule, I agree. But what commonly isn’t so clear is why; and how do you recognise a conspiracy theory anyway? It seems quite common nowadays to see conspiracy theorists where there are none, and to use it more as a set-piece debating tactic than an actual contentful argument. Pause for a moment, and try to articulate exactly why conspiracy theories are usually fallacious. Is it really the conspiracy that is the issue, or is it perhaps another sort of fallacy in disguise?
Can we say a priori, for example, that conspiracies never happen? If people never conspire secretly, then obviously we would know that any suggestion that they have would be false. But we know that there have actually been conspiracies, so it would seem at first glance that to dismiss a theory simply on the grounds that it involves a conspiracy is itself a fallacy.
Careful examination of the arguments reveals that it is in fact only a particular subset of conspiracy theories that is at issue. In fact one particular aspect, which is the total lack of evidence. When the reason for the lack of any evidence, it is claimed, is that the conspirators covered it up.
Now again, it is entirely possible that if there was a conspiracy, they would indeed try to cover it up, but this is taking the logic the wrong way round. A successful conspiracy implies there will be no evidence, but a lack of evidence does not imply a conspiracy. It may be that there is no evidence because it never happened. But conspiracy theorists are deep into confirmation bias – they are looking for anything to support their belief and reasons to dismiss contrary evidence. An argument capable of confirming or dismissing anything is ideal.
So in fact the conspiracy theory fallacy is simply a fallacious method of ignoring the evidence, or its lack.
However, the fallacy is sometimes misidentified. Sometimes it is when it is stated that some information is kept secret. Again, if the only evidence for this is that there’s no information in public, then that’s a fallacy. But if we know the information must exist, because of other data that is public, but the information itself is not, then we do indeed have positive evidence that something has been kept secret. We know there are adjustment algorithms for temperature data, because the authors have said so, and because the output does not match the input, but there are no complete or usable descriptions of them, because the only places such a description could be (the electronic archives and published papers of the authors) do not contain such.
Sometimes the fallacy is misidentified when a coordinated action by several parties has been proposed. Again, this could be a fallacy if the only evidence for such coordination is that it is necessary to explain the lack of evidence. And it could be a conspiracy theory if the only way to explain the common action is if the parties conspired first. But if people separately have a common motivation, they can all carry out the same action independently. And if it only requires a very small number of actions that are done frequently anyway, the probability will be high. Thousands of people shop at the same supermarket every week, but it does not require a conspiracy to explain it.
So when dismissing conspiracy theories, it is important to check that it really is a conspiracy theory, and that if it is, it is of the right sort.