Darwin's Dangerous Idea

Darwin's Dangerous Idea, by Daniel Dennett, one of the two most important (IMHO, of course) books I've read (Thinking, Fast and Slow is the other, already recommended, below. Dennett is a practical philosopher of science; the book is a detailed analysis and extension of the idea of "designer-free design", evolution by incremental random change. Among other things, he thoroughly presents the implications of Darwinian evolution, discusses the concept of "design space" and how some evolutions preclude whole swaths of that space, then speculates carefully on how the idea could pertain to other fields, e.g., the evolution of physical law (assuming that each "big bang" resulted in a universe with slightly different physics.