Since 9/11 was discussed the first time on OB I keep hearing this “the prior probability of a conspiracy is very low” or variations thereof. This is a totally meaningless statement, unless you can produce some actual numbers but no one made an effort to do so.
I didn’t actually say anything about my prior probability. I just said I went from a ‘pretty low’ probability of some kind of conspiracy to a slightly higher probability based on this new information.
Nonetheless, I think you are wrong to say this is a meaningless statement. I think there is a real phenomenon of ‘conspiracy theories’ which share certain features and which in my opinion tend to lead people to place unduly high probabilities on certain types of explanations for events by playing into natural biases in human thought. Because I believe in this pattern of poorly calibrated estimates, when I see a theory that fits the pattern I apply a discount factor to the arguments of people proposing it.
It is also difficult to organize and maintain a conspiracy so even independent of the effect I describe above an explanation that involves an elaborate conspiracy has a lower prior than an explanation that does not, all else being equal. It is not necessary for this to be quantified for it to be meaningful, a qualitative use of priors is still a useful aid to reasoning.
One reason the new information I mentioned above raised my estimate is that it overcame one major problem I have with the conspiracy theory explanations which is lack of a motive that I could understand. Given my broader understanding of geo-politics the disappearance of a large quantity of physical gold seems like a strong motive for some kind of government cover-up and a clearer motive for co-conspirators (government or otherwise) in the attack.
I didn’t actually say anything about my prior probability. I just said I went from a ‘pretty low’ probability of some kind of conspiracy to a slightly higher probability based on this new information.
Nonetheless, I think you are wrong to say this is a meaningless statement. I think there is a real phenomenon of ‘conspiracy theories’ which share certain features and which in my opinion tend to lead people to place unduly high probabilities on certain types of explanations for events by playing into natural biases in human thought. Because I believe in this pattern of poorly calibrated estimates, when I see a theory that fits the pattern I apply a discount factor to the arguments of people proposing it.
It is also difficult to organize and maintain a conspiracy so even independent of the effect I describe above an explanation that involves an elaborate conspiracy has a lower prior than an explanation that does not, all else being equal. It is not necessary for this to be quantified for it to be meaningful, a qualitative use of priors is still a useful aid to reasoning.
One reason the new information I mentioned above raised my estimate is that it overcame one major problem I have with the conspiracy theory explanations which is lack of a motive that I could understand. Given my broader understanding of geo-politics the disappearance of a large quantity of physical gold seems like a strong motive for some kind of government cover-up and a clearer motive for co-conspirators (government or otherwise) in the attack.