When someone criticises part of science for being 'Just a theory' you know that that person really has very little idea what scientists really do. In Just a theory : exploring the nature of science
Moti Ben-Ari takes a look at such misunderstandings, and more generally at the way science works. There's a chapter on the way scientists use words and how the this may conflict with everyday usage. Ben-Ari also discusses the philosophy of science, such as Popper's falsificationism, whether Kuhn's paradigms are an accurate description of what goes on, and what distinguishes real science from pseudoscience.
Ben-Ari examines the ideas from the sociology of science, and at how these all too easily descend into the nonsense of postmodernism. There is then a look at the relationship between religion and science followed by a chapter on the nature of reductionism. The last few chapters are a bit less argumentative, dealing with statistics, how logic and mathematics are used in science and a chapter on the Wegener's ideas on continental drift, and how they were originally laughed at. The final chapter is about the future of science - Ben-Ari predicts there won't be any more scientific revolutions, which seems a bit tame for my liking. Overall the book is clearly written and easy to read, and just what you need if you want to argue with the muddled ideas about science which some people have.