The works by the philosopher of science Thomas Kuhn have had a profound effect on my understanding of the nature of science. I can strongly recommend his books The Structure of Scientific Revolutions (1962 and revised in 1970) and The Copernican Revolution (1957).
For those who would like a shorter introduction to his ideas, this article by James A. Marcum that provides a brief biography of Kuhn as well as a summary of the ideas in Structure is good.
Kuhn views led to fierce debates about the nature of scientific knowledge within the academic world that spilled over to the general consciousness. Marcus does a good job of discussing what the controversies were about and how Kuhn reacted to them.
This link was sent to me a few days ago by a former student of mine who took my course on the evolution of scientific ideas way back in 2003. We discussed Kuhn a lot in that course and he says that he found the ideas in that course to be thought-provoking. It is always gratifying for a teacher to find that a course influenced a student’s interests and reading habits reading long after it ended.