In the comparatively short period of only two centuries, biology became one of the most interesting and both intellectually and socially influential sciences. Philosophical interest in its concepts, scientific methodology, and reliability of its results is now probably greater than it ever was before. In order to understand philosophical significance of contemporary biology, we will focus on the theory of evolution, and discuss the following questions and problems: What are the main claims of the theory of evolution, and how are we to interpret them? For example, what is an "adaptationist explanation" and under which conditions are such explanations satisfactory? What is `fitness,' and how should the concept be employed to help us provide good evolutionary explanations? What is natural selection acting upon-a species, an organism, or organism's genes? And how are we to define `species,' faced with different definitions used in different biological sciences? Darwin, and other evolutionists after him, firmly reject teleological explanations in biology-yet to explain the emergence and stability of particular traits in organisms and species we must say what purpose do these traits serve, which seems like a teleological explanation after all. How are we to resolve this apparent tension in the heart of the evolutionary theory?-Finally, in the last segment of the course, we will examine some aspects of the influence biology had on other disciplines, by studying the methods, assumptions and some specific claims of sociobiology and evolutionary psychology. Format: lecture/discussion. Requirements: class participation, two short quizzes, three 5-pages long papers, and a longer (7-10 pgs.) final paper. Prerequisites: Philosophy of Science, or three courses in biology, or (in special circumstances) consent of the instructor. Enrollment limit: 25 (expected: 5-15).