This book represents an attempt to understand the evolution of Jean Piaget's basic ideas in the context of his own intellectual development. Piaget sought to elucidate human knowledge by studying its origins and development. In this book, Michael Chapman applies the same method to Piaget's own thinking. Dr Chapman shows that some of the Swiss psychologist's essential ideas originated in adolescent philosophical speculations about the relation between science and value. These same ideas were then developed step by step in Piaget's investigations of children's cognitive development. Dr Chapman claims that Piaget's use of developmental psychology as a means for addressing questions about the evolution of knowledge has been misunderstood by psychologists approaching his work exclusively from the perspectives of their own discipline. Reconstructing Piaget's intellectual biography makes possible a better understanding of the questions he originally posed and the answers he subsequently provided. Dr Chapman concludes with an assessment of Piaget's relevance for contemporary psychology and philosophy and suggests ways in which Piagetian theory might be further developed.