  It is, however, the work of Jean Piaget that has been most influential on the way psychologists, educators, and even philosophers have come to think about the cognitive development of children. Piaget’s early work, The Child’s Conception of the World (1929), makes especially clear how philosophically challenging the work of a developmental psychologist can be. Although his project is always to lay out identifiable stages in which children come to understand what, say, causality or thinking or whatever is, the intelligibility of his account presupposes that there are satisfactory responses to the philosophical quandaries that topics like causality, thinking, and life raise.