The Uncomfortable Position of "I Don't Know"
TLDR; "I don't Know" is a perfectly reasonable position when you don't have sufficient knowledge/evidence.
There's something very uncomfortable about being asked a question and not knowing the answer. Maybe it's something left over from childhood when the teacher calls on you? You can't let the teacher know you didn't do your homework, so you just make a guess and pretend you know what's going on.
In our adult lives, wouldn't we be better off admitting when we're ignorant? I remember early in my career when I was fearful of being found ignorant of aspects of my profession. When confronted with something I didn't know about, I would just pretend and go along only later to study feverishly to try to catch up with the others. I'm undoubtedly still guilty of this behavior on occasion, but more often now I'll admit my ignorance on the spot. I've found that instead of being seen as an ignoramous, my peers are excited at the opportunity to share their knowledge with someone who is interested. This change has helped me to learn new things more quickly, and it has (I think) made me a more likeable person.
I think this is a lesson that the world needs right now. People are afraid of losing some kind of authority so they speak and think authoritatively to compensate. While seeking acceptance and admiration, they're making dangerous assumptions. We're missing the opportunity to learn from each other. It's always fear.