Theory and Reality: An Introduction to the Philosophy of Science (Peter Godfrey-Smith)
This is another popular introductory text in the philosophy of science. I've taught from it myself, and it's very good.
The book is intended for undergraduates and general readers with no prior background in philosophy. It covers similar ground as the Alan Chalmers book, but Godfrey-Smith's writing style is livelier and more engaging generally, in my opinion. It's always nice to see how different authors discuss the same material. Godfrey-Smith is a very active researcher and writer in the field, and his perspective on these issues is one that I respect.
The text covers covers logical positivism; the problems of induction and confirmation; Karl Popper's theory of science; Thomas Kuhn and "scientific revolutions"; the views of Imre Lakatos, Larry Laudan, and Paul Feyerabend; and challenges to the field from sociology of science, feminism, and science studies.
The book then looks in more detail at some specific problems and theories, including scientific realism, the theory-ladeness of observation, scientific explanation, and Bayesianism.
In the final section, Godfrey-Smith defends a form of philosophical naturalism as the best way to solve the main problems in the field.