Identity and Discrimination

When do two experiences have the same subjective character? What unifies the life of a person? How can animals be grouped into species? Are Latin and Italian different stages of the same language? Could HMS Victory have been made of different planks and still be the same ship? Timothy Williamson argues that these and other questions give rise to philosophical problems with the same underlying structure. In each case, common sense assumptions lead to slippery slope paradoxes. This book proposes a new and unified resolution to these problems, based on techniques from mathematical logic. It requires positions to be taken up on current controversies about vagueness, observation and necessity; the work of philosophers such as Michael Dummett, Crispin Wright, Nathan Salmon and Graeme Forbes is discussed. "Identity" addresses in an original and rigorous way the necessity of discrimination and the thresholds which determine the approximate criteria of identity.