in reply to What do you know, and how do you know that you know it?
The main question which you must ask yourself, is "what is the big picture" to you? Is it corporate profits, or world economy, or world peace, or even " how does it affect the creation fields in the quantuum foam" ?
So it is up to the observer to know the limits of his "big picture", and to keep in the back of his mind that "there is always something bigger".
I just saw a sig in a post here recently(maybe yours?)......
An intellectual is someone whose mind watches itself. -- Albert Camus