Learn English – Word or phrase for someone devoid of logical reasoning/employs irrational thought

Is there a word or phrase, pejorative or otherwise, for someone who is not equipped with the tools of rationality? E.g.

A: "Every time I wear my lucky shirt I get more green traffic lights."

B: "Maybe you just notice green lights more when you are wearing your lucky shirt because you believe it to be lucky?"

A: "No, I definitely hit more green lights. I wore it to the Super Bowl and hit every green on the way out the city."

B: "Oh, interesting. Did you consider the lights may be configured that way to get better through flow of traffic in busy periods? In traffic management they call it a 'green wave'."

A: "How would you know? You don't even drive."

Or in political argument:

A: "The Holocaust is a lie."

B: "What make you say that?"

A: "I just know it."

B: "How do you know it?"

A: "My uncle is German, he says so."

Etc. Etc.

Example sentence: "A is such a […], trying to have a rational argument with him is like bashing your head against a brick wall."

I feel like "airhead" or "simpleton" would come close but I feel that those imply stupidity and, in society's eyes, stupidity doesn't infer irrationality.

Please note: I am not trying to infer madness or eccentricity. More like "the opposite of someone you would find on a debate team."