Almost anyone who is involved in some kind of research activities with the purpose of producing knowledge is also reflecting on what science really is and what it means. I have had these questions almost as a hobby since I was a student and am still curious. A few years ago, my colleague Harold Nelson told me about a book about this topic. It is John Ziman's "Real Science -- What it is, and what it means".
After having read a lot of general philosophy and philosophy of science over the years, to read
Ziman's book is refreshing. Ziman was a physicist (1925-2005). His primary area was theoretical physics and quantum theory, but he also became quite active in the philosophy of science.
To be honest I have to confess that I have had this book for some year but not yet read the whole book, but some chapters I have read more than once. Ziman takes a very concrete view on science. He describes research as a practice where people engage in activities that are quite practical and pragmatic. But what I find most valuable in the book is the way Ziman defines concepts such as universalism, unification, objectivity, originality, etc. And particularly how he defines the notion of theory. The definition of theory is in my mind the best and most useful definition that I have encountered. The chapter called "Universalism and unification" is wonderful! I think this chapter should be read by every PhD student and active researcher.
Well, I will continue to read the book. I have several chapters I have not carefully read yet.