As notions of postmodernism and deconstruction have become exceedingly fashionable in recent times, scholars have attempted to remake epistemology as a subjectivist enterprise. Why Science Needs Metaphysics deplores this state of affairs and attempts to correct it by reviving rational metaphysics as well as some of the sound ideas of the Vienna circle. (A rational metaphysics maintains that the world around us is real, and has a specific nature independent of our thoughts or feelings.) In arguing for a rational metaphysics, Zahar corrects and extends Karl Popper's approach to epistemological problems and develops Lakatos's Methodology of Scientific Research Programs into his own methodology. The book ends with two short case studies, one on the development of atomic theory, and the other on Einstein's philosophy of science. Both illustrate that realist metaphysics are crucial to the work of our greatest scientists.