A presentation of current work that systematically explores and articulates the nature, origin and development of reasoning, this volume's primary aim is to describe and examine contemporary theory and research findings on the topic of deductive reasoning. Many contributors believe concepts such as "structure," "competence," and "mental logic" are necessary features for a complete understanding of reasoning. As the book emanates from a Jean Piaget Symposium, his theory of intellectual development as the standard contemporary treatment of deductive reasoning is used as the context in which the contributors elaborate on their own perceptions.