One of my favourite books is “Follies and Fallacies in Medicine”. It has been out of print for some time but Lucy Skrabanek has kindly made the book available as a pdf file. You can find it at http://chagall.med.cornell.
On the same lines there is an interesting BMJ Blog by Peter Arnold entitled “I don’t know”. There is and interesting overlap between this article and the forward to Follies and Fallacies in Medicine in which Skrabanek and McCormick refer to being infected with “skepticaemia”. The very first step towards using Evidence in Patient-care is recognising that there is much we do not know.
“It ain’t what you don’t know that gets you into trouble. It’s what you know for sure that just ain’t so.”