Reductionism is one of those philosophical myths that are either enthusiastically embraced or wholeheartedly rejected. And, like all other philosophical myths, it rarely gets serious consideration. Reasoning About Theoretical Entities strives to give reductionism its day in court, as it were, by explicitly developing several versions of the reductionist project and assessing their merits within the framework of modern symbolic logic. Not since the days of Carnap's Aufbau has reductionism received such close attention (albeit in a necessarily restricted and regimented setting such as that of modern mathematical logic). As such this book fills a void in the philosophical literature and presents a challenge to every would-be (anti-)reductionist. It should be required reading for every first-year graduate student in philosophy.