When people first encounter philosophy, they want to-know what it is about. Other disciplines have their own subject matter: biology is the study of life processes, sociology is the study of human societies, astronomy looks at planets and stars, etc. So what is philosophy about? Those who are not new to the study of philosophy know that what makes philosophy a separate discipl ine is not its special subject matter. True, there are questions that we naturally think of as 'philosophical ' in some sense. Questions such as, 'How should I live my life?', and 'How do we know anything?', and ' How did all this come to be'?'. But the first question is also addressed by literature, the second by cognitive science, and the third by astrophysics. What distinguishes philosophy from other disciplines?