When Piaget ascribed the origin of knowledge to action, he distanced his theory from most other theories of the origins of mind. As a result, Piaget's conception of mental action has been quite controversial. Piaget's recent, functionalist revisions emphasize procedures and their role in the development of structures. In the new view, structures…

Piaget's theory has been characterized as descriptive and not explanatory, not qualifying as causal explanation. Piaget was consistent in showing how his theory was both explanatory and causal. Vygotsky also endorsed causal-genetic explanation but, on the basis of knowledge of only Piaget's earliest works, he claimed that Piaget's theory was not…