Thanks for your reply!
To be clear, if you explained yourself to your friend and they harangued you about it, I totally understand not replying to them. If you fall out of contact on accident, I also understand. It's not replying at all when people ask why they haven't heard from you that I don't understand.
If I can't think of an explanation I may just fail to respond. This happens to me a lot as I get busy and forget to pay sufficient attention to social things for too long. Then by the time I get back into a social mode, there may be a whole pile of messages from different people I should deal with, and a process of triage begins where I start by responding to the ones I consider most urgent at that moment. Unfortunately some messages will be low on the list, and "why aren't you responding to me" would be especially low if I cannot come up with...
The other day, someone did something I didn't expect. It was something many people have done before; something that I thought of as very normal, but that I in no way understood and had not predicted.
As I said, this had happened many time before, so I wrote it off as "me not understanding people" or "people are weird" for a second, like I usually do, before realizing that "bad at" really means "lacking basic knowledge", which I had never realized before.
And then I thought "I should ask someone who is different from me why people do that, and eventually someone will have an answer."
But many people will have many more questions like this. So, what have you observed people doing time and time again, but never understood? Or something that you only understood after a long time or asking someone about it?
And can Less Wrong tell us, not necessarily why (I for one can make up evolutionary psychology fairy tales all day if I want) but what conscious thought process occurs behind these events?