There are a couple individuals here who fall into this category. I'm not so much interested in their opinions (as they don't actually have any). I'm more curious as to how thinking people interact with them.
I don't know if maybe I would fall into this category from your perspective. You do see a lot the notion that someone who disagrees with you is automatically less intelligent because given a similar starting point and similar data they arrive at dissimilar conclusions. Not that I particularly remember specific discssions with you.
I think it's like this: human beings are not well-disposed to rational thought. There are certain patterns of behaviour you see all the time, which are flawed reasoning, but go unrecognised (or worse, recognised but not countered):
1 - Confirmation bias - where a person gets an idea in their head - which can be extraordinarily irrational - and then looks for data which supports his or her position while subconsciously dismissing that which disagrees with their hypothesis. It's putting the cart before the horse compared to ideal scientific method which should always loop around the question: am I wrong (sorta). If you know how easy it is, even with a high IQ to get this wrong it is deeply disturbing below that level.
2 - Communism of opinion - Probably social media has amplified this in the last decade: everyone's opinion is equal, and that belief is the same as evidence or rigorous thought or hard-earned knowledge. It isn't. Like you believe the earth is round is irrelevant to reality. Also as mentioned in the Kruger effect; on a non-linear scale slightly lower Wattage lightbulbs are convinced they are as bright as he brightest bulbs in the store.
3 - Combat versus discussion - If you've ever mixed in circles of highly intelligent and educated people conversations tend not to be centred on what they know and the associated prestige / payment / respect they ought to get for that. Expertise in this field or that is acknowledged but hardly traded. Those conversations go more along the lines of what they don't know and how far they can extrapolate and reason with available data. In 'daily life' and the media quite the opposite is the norm. Everyone is sure they're right, shouting at each other with absolute certainty and anger, devoid of the previously mentioned phenomenon of considering they're wrong or at least partially wrong. Or indeed that there can be compromise or a solution agreed upon with a suitably broad tolerance. It's just far easier to go to war. For a bit longer anyway.
4 - Societal division - historically human deveopment has profited considerably from pitching one group against another and having them duke it out. There is no bottom limit to this: even in democracy. In a recent pole the majority of Bavarians wanted to form their own breakaway state. Amplifying differences instead of identifying commonality is a fool's game. Look at racism as a term. There were about 16 viable races of humanity at one point, it is theorised and we are the only one left. One people. Fact, as Zack used to say.
5 - Individual intelligence - Individuals can be clever, but institutions, organisations, groups of people tend to reduce to a certain holistic common denominator. For instance the former Japanese nucear programme, employing the kind of reactors they did, in the locations they did, with the placement of disaster measures was truly, really, profoundly stupid despite it being a multi-million dollar / yen installation. All of the above four points dominate in groups of heirarchical organisation.
It's interesting to sometimes watch groups of children. Yes they can be savage and violent (because they aren't so civilised) yet also empathic, caring, patient. Sometimes it leaves you with the thought: what do we lose as we grow and become indoctrinated?
Well now, that's quite enough procrastination for me for one evening. I have some difficult formulae to encode...
