From: Fastfission fastfission@gmail.com

I think a good line of work with NOR is to say that every fact which could be reasonably contested should be cited. That is, if I write an article the History of X, and I say that on such-and-such a date, so-and-so did something, I might from the get-go assume that this is common knowledge (at least among specialists). If someone comes to the talk page and says, "Hey, I don't know about that," then it is my duty to pull out some other source which says it. I think citation is allowed to be an evolving thing.

I think this is _exactly_ right. And ought to apply to other situations involving "common knowledge" among people reasonably knowledgeable about the topic.