Four factors:<p>0. Intelligence is hard to &quot;measure;&quot; and even informally, there are mostly inferred attribute from a subject&#x27;s performance filtered through the viewer&#x27;s (fallible&#x2F;biased) perception.<p>1. There&#x27;s many domains of intelligence:<p>- critical thinking (i.e., lawyers)
- fact memory
- abstract thinking
- spatial
- problem solving 
- social
- political
- emotional<p>... and far too many others to list.<p>2. Biases - upbringing, environment, experiences and so on tend to influence a person&#x27;s preferences and beliefs, and they may be expressing what it is their social group expects or how they view themselves.<p>3. I&#x27;m sure there is at least one belief each of us clings to that others find wacky.  Sometimes person don&#x27;t pick up that a certain view is social unacceptable.  Examples:<p>- The guy in Starbucks with backpack supporting &quot;the missile men of gaza&quot;... de-facto endorsement of terrorism.
- I happen to be vegetarian (not driving around with &quot;meat is murder&quot; and slaughterhouse shame pictures)... a lot of people are offended by that and heap on certain biases.
- People struggling to survive, yet don&#x27;t support unions, basic income or higher taxes on large trusts and estates, and are still libertarian &quot;completely unregulated market&quot; types.