This indispensable new edition brings Chalmers' popular text up to date with contemporary trends and confirms its status as the best introductory textbook on the philosophy of science. This revised and extended edition offers a concise and illuminating treatment of major developments in the field over the last two decades, with the same accessible style which ensured the popularity of previous editions. Of particular importance is the examination of Bayesianism and the new experimentalism, as well as new chapters on the nature of scientific laws and recent trends in the realism versus anti-realism debate.