Duncan Watts has a book titled Everything Is Obvious: Once You Know the Answer Very good and interesting read.

http://www.amazon.com/Everything-Is-Obvious-Once-Answer/dp/0...

> A lot of things seem obvious if you know the answer. [...] Also, a lot of things that seem fairly common sense turn out to be wrong when you subject them to empirical testing, so be careful about the applying the 'common sense' filter.

A Yahoo researcher wrote a book about this very thing:

http://www.amazon.com/Everything-Obvious-Once-Know-Answer/dp...