So true. If one looks closely at actual (as opposed to the false caricature most people hold in their mind) "conspiracy theories", very often they are based on reasonable questions or the desire for more details & study, with a big percentage of actual idiots also participating in the discussion. And when you observe their detractors, say on here or reddit, you will usually see an unfortunate strawman or worst-possible-interpretation approach being taken to claims being discussed.

The human mind is extremely susceptible to various fallacies such as confirmation bias. Usually this is beneficial, but often it can be very harmful.

> Some of the people who believe these things are not stupid at all

I don't think it's productive to label anyone stupid, but a complete inability to properly weigh probability is damning to claims of intelligence. For instance, the scope of the conspiracy needed to fake the moon landings is completely implausible. And when you consider the incentive the USSR would have had in exposing it as a hoax, it goes from implausible to literally impossible. Similar arguments apply to the safety of vaccines, flat Earth, and other absurd hoaxes.

This is considerably different to the repetition of "common knowledge" which ultimately turns out to be some kind of urban legend.

Probability is also based on what you know. Nobody believed NSA was collating information about Americans online the way they did, so using probability you don't reach the correct answer. The CIA is smuggling drugs and has committed lots of serious crimes across the world. Again, what is the probability of this?

Quite a few people believed the NSA were collecting everything, but I agree that quantifying what you don't know is challenging. Even so, you often don't need to precisely quantify each outcome so long as you can calculate a relative difference between the various outcomes you are aware of. Most questions in daily lifehave order of magnitude differences between them.

> If you truly want to understand, you need to be open to the possibility that they are right.

Chickenpox is not a horrible disease that ought to be vaccinated against. Pro-vaxxers don't realize that they're missing the big picture too: we can't vaccinate against everything, and it's just as important to address all the conditions that result in children developing an especially bad case of chicken pox.

Medicine is a fickle field. The tragedy is that modern medical practitioners think they now know what they're doing. Otto Warburg was probably always right about cancer [0], but conventional doctors are still working with the 'kill all the cancer cells' theories of cancer treatment.

[0] https://www.nytimes.com/2016/05/15/magazine/warburg-effect-a...

> I've been working with professionals a lot, and I know they are just repeating what they are told. Every profession is like that. Experts even more so, since otherwise they lose credibility and are not experts anymore.

There's a human tendency to trust "received wisdom". I think Thomas Kuhn's book, The Structure of Scientific Revolutions, is about the phenomenon...

Professionals who build things that are expected to just work (bridge engineers) are a little different than professionals who try real hard to help their patients (certain medical specialties).