"Stupid" is not a useful way to generally describe the people vulnerable to conspiracy theories. I have met people who are relatively intelligent who fall into these. See also: religion, politics.
Fields that require carefully examined beliefs about almost everything (physics for example) are a lot harder to pull that off in.
The irony happens when it is education itself that compromises the critical faculties of someone, as the article mentions.
Intelligent people are sometimes loyal to an ideology built during their upbringing and belong to their circle. Sometimes the exact opposite happens and drives them to a complete rejection of said ideas. Religion, culture, and politics are prone to create blind spots, where otherwise critical, highly educated, and intelligent individuals don't question specific biases because they are too closely related to their identity.
If it encompasses the inability to reliably connect thoughts to reality, inability to trust anything other than naive constructs and actively distrusting others (which will certainly limit the problem space in which they can work), then it serves as a good shorthand.
Do you have any better suggestions (that aren't full sentences or paragraphs)?
> people want some understanding of what's happening, but they're not getting it from the media, they're not getting it from the intellectual classes, they're certainly not getting it from the government
[..]
> it's happening all over and I think you can trace a good deal of it to the effect of neo-liberalism. It had a goal remember: the goal of neo-liberalism was to transfer decisions away from the public to the hands of private power and to atomize the population.
-- Noam Chomsky, https://www.youtube.com/watch?v=uiCeqySVhCE&t=20m55s
> the individual citizen has very little possibility of having any influence - of making his opinion felt in the decision-making. And I think that, in itself, leads to a good deal of political lethargy and stupidity. It is true that one has to think first and then to act - but it's also true that if one has no possibility of acting, one's thinking kind of becomes empty and stupid.
-- Erich Fromm, https://hrc.contentdm.oclc.org/digital/collection/p15878coll...
Religion is too broad a term to sweep everyone under. It’s very diverse.
Now creationists, who believe the world is 5.000 years old - yeah, that’s a whole other bag-of-fish.
https://enki.org/2018/07/30/things-i-learned-in-elementary-s...
The belief on the creationist side is that this original event must have a cause, because everything else in the universe that we can empirically study obeys that principle.
The belief on the atheist side, for lack of a better label, is that the universe was/got created out of nothing. It must be possible for it to occur without God, in the purest sense of the word atheist.
But whether God created it or it created itself, there are only interpretations and no direct empirical evidence.
Yes, one can be a creationist and choose to believe that God created the universe with a big bang. But some creationists literally believe that the Earth was created in six days.