educated at British Columbia and Trinity College, Cambridge, and now centred in Toronto and Paris where he holds a Chair at the Collège de France. Hacking has written widely on the philosophy of probability and the philosophy of science in general. He has been especially interested in the social background and historical conditions underlying the emergence of particular scientific concepts. Early books included The Logic of Statistical Inference (1965) and Why Does Language Matter to Philosophy? (1975). The Emergence of Probability (1975) and The Taming of Chance (1990) are contributions to the philosophy and history of probability. His Representing and Intervening (1983) emphasized the role of experiment in the natural sciences, while Le Plus pur nominalisme (1993), concerned Goodman’s paradox. The social aspect of medical concepts are discussed in Rewriting the Soul: Multiple Personality and the Politics of Memory (1995), Mad Travelers (1998) and The Social Construction of What? (1999).