Introduction

Abstract

Throughout his career, Piaget has always concerned himself with problems of genetic epistemology, for to him the question of what is contributed to human knowledge by the knowing subject and what by the object to be known can be answered scientifically only if the question is asked in terms of growth—and hence of transformations—of knowledge. In other words, for Piaget knowledge does not exist in static form but is a constructive process characterized by its origin and development. As his field of study he consequently chose children’s ideas at various stages of cognitive development. The method of investigation that has now been used by Piaget and his co-workers for some 50 years is psychogenetic experimentation, which seeks to determine the stages or levels in the construction of knowledge, their developmental links, as well as the mechanisms through which a consistent system of logical reasoning and of explaining the physical world is built up.