It is popularly alleged that all of science reduces to physics. If this is true, it presents an obvious puzzle: Why do people waste time pursuing chemistry, geology, biology, or psychology? One standard answer is that it would be too difficult to conduct all the sciences in terms of physics. This is right, but illuminates only the least interesting part of the picture. Our focus in this course will be on psychology, as psychology presents some of the more difficult and exciting challenges in the philosophy of science. We will critically investigate the claim that psychology engages in a manner of explanation all its own. Along the way, we will tour the history of psychology from the Enlightenment through this century. This is a course for philosophers who are hoping for an introduction to the philosophy of psychology, for psychologists who are seeking a better understanding of what an explanation in psychology is, and for the scientist who wonders whether physics exhausts scientific inquiry. Requirements: weekly short writing assignments (3-4 pages) and one longer final paper (12-15 pages). No prerequisites, although Philosophy 102 and at least one course in psychology, computer science, or neuroscience are highly recommended.