Who fits this description?

They never let facts, logic, reasonableness or common sense stand in the way of their firmly held preconceptions, cherished beliefs, illogical opinions, gut assumptions, and conditioned preferences.

Indeed. Who does that shoe fit? 

Is it a function of age? Education? Skin color? Where they reside? Gender? Occupation? Maybe one of several other possible demographics?

Since we're in the political season [when were we not?] the easy answer for us here in the US of A would be easy to reach: either Democrats ... or, Republicans. Left leaning, versus right leaning. The correct answer to that being nothing more than where you happen to stand. Like in war. Each side is the enemy to the other. 

My issue with that is depending on which side of the political divide you're on, each side points the finger at the other one. I'm right you're wrong standing face to face opposite the other with the same goddam position. 

So how do we understand how half the folks see white, while the other half sees black? Just what is the common denominator?

People. Yes, being a person. That is the common factor. A human being. Human in the sense of having the technical anatomical and physiological makeups which define a human being. Not human in the more aesthetic, spiritual sense which can be understood to be an embodied soul living to perfect itself in the eyes of God according to its inherent natural potential. 

Mix into that that who doesn't like being right. Not right, as in conservative right. But, right, as in correct. God is on our side right. 

But the adamant sticking to being right no matter the facts or reasonableness of things ... that's the action of the ego. The devil, really. The one who stands for fictions as true and seduces us into a false sense of who we are.

As in war, this adamant taking of sides is a violence. A violence to the soul, to humanity. 

I don't think my saying that will add one lick of difference. For me, it's just the satisfaction of putting my thoughts on paper. If any of that fires your imagination, that's great too.