A famous Donald Rumsfeld quote goes:

There are known knowns. There are things we know that we know. There are known unknowns. That is to say, there are things that we now know we don't know. But there are also unknown unknowns. There are things we do not know we don't know. ...

All well and good. But something's missing: the unknown knowns—things we don't know that we know. Subconscious wisdom and tacit knowledge, ...

(cf. Ideas and Arguments (2000-07-22), Prusak Conversation 2 (2000-10-23), BuckMantras (2001-04-13), ...) - ^z - 2008-08-29

(correlates: Comments on Unknown Knowns, PlusUltra, SmallIdeas, ...)