What it really comes down to is these people severely lack in critical thinking, so while it is surprising that they fail to account for other, seemingly obvious externalities, it really shouldn’t be.
This critical thinking critique is pretty tautological. In effect we are saying "these people with wrong ideas, the problem is they are not good at getting ideas right".
But that isn't useful/actionable knowledge. WHY are they bad at getting ideas right? Is it innate to the average human biology? Is it something that has gotten worse as more people have gotten onto the internet where they are exposed to non-curated data more?
True. I think the actual cause is definitely multi-faceted, and expect a big cause is education. Both quality of that received (eg state funding), and level attained.
Others have also mentioned other salient factors (psychology, etc)
I think it is an natural personality trait gone haywire. Just as there are some people who are pure herd creatures, completely trusting of authority, there are others who are inherently skeptical as a genetic trait. Humanity benefits from a certain degree of skepticism but since it's a spectrum, some people possess it in excess. In antiquity such people may have been heretics who questioned the Church, and they led us to the Reformation and to scientific progress. In the more recent past, they believed in alien landings and the Bermuda Triangle. Nowadays they're anti-vaxxers or flat Earthers, viewing the government or scientific orthodoxy as windmills to tilt against.
Perhaps our current environment is to some extent conducive to runaway skepticism. Consider, obesity is rampant because human beings evolved in relative caloric scarcity, but in today's plentiful, carbohydrate rich diet, we find it hard to self-regulate our food intake. Perhaps conspiracy-theorism is rampant because humanity evolved in an environment where people were much less free to pursue their "alternative" urges, but the shackles have been loosened in the modern world. Freedom for better or worse also means freedom to hold fringe points of view.
We are naturally far better at identifying what's plausible instead of sorting out what is likely, and we're better at giving kudos and recognition for the former than the latter even though it's easier. That makes some people hyperdevelop "theorizing" without working on "validation."
We are dangerously good at making up stories to explain data. Talk to anyone about a spurious correlation[0] and they can provide you a just-so story that explains it as a real correlation in under a minute.
Provide anyone with two competing theories that each account for some but not all of the available data, then ask them to rank the two based on likelihood. You'll make people visibly upset. (Our ability to invent new theories to fit any circumstance might partly explain why, for a while, explorers forgot how to cure scurvy.[1])
And it's easier to "look smart" the first way. No one can immediately determine whether you're good at the second unless you make a long series of predictions evaluated over time while constantly gathering more data. Everyone can see if you've connected a few dots in a clever and unexpected way. Talking heads are regarded as experts for going on shows and making vague predictions based on a few recent events, but are never called back to scrutinize their predictive track record.[2]
Conspiracy theorists are generally just arguing something is plausible, and ignoring the messy step about what's more likely, with the implication you should just leap from plausible immediately to unwavering conviction.
Some of this is just, well, one of these things is hard and the other is easy. But I'm confident both can be learned to some extent, based on personal experience of getting a better sense for these over time.
So to the extent this is "fixable" at all,[3] maybe greater education about meta-cognition (esp. cognitive biases), the history of analytic philosophy, a humility about what one knows, and/or Bayesian reasoning earlier in education might help.
Sidenote, this itself is arguably just another just-so theory too. Maybe I'm wrong about it all. :)
[2] This is Phillip Tetlock's whole area of research.
[3] To be fair, maybe we've already "fixed" this pretty well, we tend to attribute far fewer things to witchcraft than a few hundred years ago, maybe normal everyday education and expansion of literacy is enough and there will always be a handful of outliers and trolls. See also: https://slatestarcodex.com/2013/04/12/noisy-poll-results-and...
The real issue is that they are disproportionately loud. Since they spend no time researching, they can spend all of their time being as loud and obnoxious as possible.
...and many of them make a living from the entertainment value of their conspiracy theories.
What compounds their out-sized impact is the attention the media pays to them. Every time they they are featured by some reporter, social media site, or local media channel, they receive a fresh new set of subscribers.
Rather than feeding these beasts, we need to learn to IGNORE idiocy.
It's not all lack of critical thinking. It's also that it can be kind of fun to make out you and your friends are the ones who know the truth and the rest of the world are idiots. I mean many conspiracy theorists would be capable of researching the kind of stuff Armstrong uses in refutation but don't want to go there.
