Conspiracy theories are different, though because they start with a “what if” and move to belief instead of starting from evidence and moving to belief.
At least, this is the way I define the terms.
People aren't rational. They are rationalizers.
Rational thinking is when you use facts and draw a conclusion.
Rationalizing is when you have a conclusion, and you work backwards to justify it with rational-sounding arguments.
Conspiracy theories start with some ridiculous conclusion, and work backwards to make it sound intelligent. It's not intelligent, but it SOUNDS intelligent.
In college we had to read Freud's Civilization and its Discontents for a literature class. The only thing I remember about that entire book was him saying that no matter what, if people wanted to do something, they would find a way to rationalize it to themselves to avoid cognitive dissonance.
That one concept has been illustrated over and over in the 30 years since!
Any theory which alleges that some group of people secretly controls the world falls under #1. Trying to keep just 50 or 100 people organized and getting them to all do what you want is incredibly hard, let alone the entire world.
An example of #2: Here in Zambia, when the government started offering free COVID-19 vaccines, various conspiracy theories spread on social media: some said that anyone who accepted the vaccine would turn into a chimpanzee, others said that their bodies would become magnetic and attract iron objects, while others said that vaccinated persons would become sterile and be unable to produce children.
I don't think any advocate of these theories ever explained why the government would want to turn their citizens into chimpanzees, though.
Understanding the capabilities and motives of others depends on haaving developed a theory of mind.
Going by Keagans developmental stages, people are getting stuck in stage 3.