I heard Russel Brand once say something like the mark of an intelligent man is the ability to hold two conflicting ideas. And then I remembered his first TV job as Big Brother's Big Mouth!

That’s a quote from F. Scott Fitzgerald.

https://quoteinvestigator.com/2020/01/05/intelligence/

However, holding two conflicting ideas and not even realising the contradictions is a mark of a brainwashed individual.