The Three Domains of Unknown
I always used to try and distinguish when attacking a problem between what I call "The Three Domains of Unknown":
1. questions for which the answers are obvious (70%)
2. questions for which I can find the answers (20%)
3. questions that I am not even aware I'd need to be asking (10%).
These latter ones are the dangerous ones that can kill you. I think that group knowledge should always be applied to this third domain, as it is best attached with out of the box thinking approaches, which reinforce each other in a loosely organized, provocative meeting.
The first group is of course subjective, what is obvious to one person could be baffling to an other. The point is that when you attack a problem you will recognize this domain right away.
Maybe the second is the most intriguing: you can find the answers as long as you know where to look for them. You ask collegues, friends, relatives. Or you can ask Google. Maybe you should ask Google first, and if you don't, collegues, and friends, and relatives might send you to some specific site to understand why