Philosophy of science is a discipline that studies the nature, methodology and scope of scientific inquiry. Traditionally, it deals with topics such as the demarcation between science and pseudo-science, the nature of scientific explanation, the logical structure of scientific theories, the empirical confirmation of scientific theories, the significance of scientific revolutions, the nature of scientific laws, etc.
Why study philosophy of science? Whether you are a science student or not, you encounter claims on a daily basis whose validation comes from being "scientific." You are to a large extent socially expected to give your assent to claims alleged to be scientific. As a matter of fact, science is today's most powerful social institution in that it alone has the power to change beliefs en masse over very short periods of time. Nowadays, adding the epithet "scientific" to an assertion lends it the highest degree of credibility. Accordingly, it is important to refine our conception of what science is, is not, does, does not, can do, can't do, etc. The objective of this introductory course in philosophy of science is to give you conceptual tools to exert critical thought in this respect. No prior background in science or philosophy is assumed for this course, but a willingness to examine abstract problems, arguments, and theories will be required.
Now, it is often claimed that the best way to understand the nature and methodology of science is by doing science: Why appeal to philosophy to discuss science? Aren't scientists the most qualified people to discuss the scientific method? Such claims ignore the diversity of practices of scientific justification across the fields. As O. Neurath once said,
[t]here is no scientific method. There are only scientific methods. And each of these is fragile; replaceable, indeed destined for replacement; contested from decade to decade, from discipline to discipline, even from lab to lab.
Philosophers of science try to find the objective principles that give grounds to the particular "methods" that scientists adopt at different time, for different problems, in different disciplines. Thus, philosophy of science studies the common conceptual ground justifying the adoption of particular "methods" in different circumstances. Accordingly, for the same reason that you can be good at riding a bike without knowing how you achieve it, you can be good at doing science without knowing exactly why what you're doing is right. It is in this respect that philosophy of science constitutes a valuable type of enquiry on the nature, methodology, and scope of science.