Book Review of: Hasok Chang: Is Water H2O? Evidence, Pluralism and Realism, Dordrecht: Springer, 2012

has written a most remarkable book that draws lessons from the history of chemistry for general philosophy of science. His historiographical focus is on the period from the late 18th century to the mid-19th century, when chemistry through its early professionalization was indeed the dominating science in Europe. He selects three subsequent episodes, the Chemical Revolution, early electrochemistry after Volta's invention of his electric pile, and the development of atomic and constitutional chemistry, which he all relates to each other by his guiding question: Is Water H 2 O? What the mainstream analytical philosopher of science takes for granted from elementary high school courses in chemistry (or the consumption of a misleading paper by Hilary Putnam), Chang picks to pieces by historical and philosophical analysis. In fact he convincingly argues that the customary answer in the affirmative has never been fully conclusive – up to today! Shaking the grounds of conventional wisdom, he suggests 'active realism' and 'epistemic pluralism' as the philosophical positions that are most appropriate for the scientific endeavor. With a strong interest in alternatives and less-successful approaches in science, and a profound understanding of experimental practice, Chang digs out neglected work in the history of chemistry that whiggish, winner-celebrating historiography has frequently made us ignorant of. While Joseph Priestley has been made famous for his stubborn rejection of Lavoisier's chemistry, the author takes him seriously in chapter 1 and rehabilitates the phlogiston theory as being not inferior to the oxygen theory (see also his 'The Hidden History of Phlogiston', in Hyle, 16-2 (2010) pp. 47-79). Thus, the well-known 'synthesis' experiment of water (by Scheele and Cavendish) could with equal evidence be interpreted as the reaction of phlogisticated and dephlogisticated water, leaving water an element rather than a compound. Moreover, in what he calls 'counterfactual history of science', Chang argues