I would also highly suggest Giere's book, Understanding Scientific Reasoning: http://www.amazon.com/gp/product/015506326X/ref=as_li_tl?ie=...

It's a textbook so it's a bit denser than a standard nonfiction offering, but it explains the perspectives of a few famous philosophers of science, the scientific method, clears up some common misunderstandings, and is packed with case studies which make the concepts easy to understand. It's a great piece for either reference or learning about science in general.