Source: How To Understand Things, by Nabeel Qureshi
What we call ‘intelligence’ is as much about virtues such as honesty, integrity, and bravery, as it is about ‘raw intellect.’
Intelligent people simply aren’t willing to accept answers that they don’t understand — no matter how many other people try to convince them of it, or how many other people believe it, if they aren’t able to convince them selves of it, they won’t accept it.
One component of it is energy: thinking hard takes effort, and it’s much easier to just stop at an answer that seems to make sense, than to pursue everything that you don’t quite get down an endless, and rapidly proliferating, series of rabbit holes. … But it’s not just energy. You have to be able to motivate yourself to spend large quantities of energy on a problem, which means on some level that not understanding something — or having a bug in your thinking — bothers you a lot. You have the drive, the will to know.
Related to this is honesty, or integrity: a sort of compulsive unwillingness, or inability, to lie to yourself.
Another quality I have noticed in very intelligent people is being unafraid to look stupid. … Most people are not willing to do this — looking stupid takes courage, and sometimes it’s easier to just let things slide.
The best thing I have read on really understanding things is the Sequences, especially the section on Noticing Confusion.
understanding is not a binary “yes/no”. It has layers of depth.