When Jean Piaget met Susan and Nathan Isaacs.

A signature event in the intellectual life of Jean Piaget occurred when he met Susan and Nathan Isaacs. Although the Isaacs were supporters of much of Piaget's theoretical and empirical work, they also advanced substantial objections to his methodology, empirical results, and theoretical interpretations. Susan Isaacs' empirical observations provided much of the evidence in support of their different views of proper methodology, intellectual development, and pedagogical philosophy. In addition, Nathan Isaacs' theoretical and philosophical arguments were set against Piaget's arguments about cognitive development. This decade-long interaction influenced Piaget in a variety of ways, both theoretically and methodologically. Their critique of his clinical method encouraged him to focus more on studying the actions of children by nonverbal means, something Piaget had recently undertaken with his newborn infants. In addition, their conceptual and empirical objections were weighty enough for Piaget to write a major (largely unknown) explicit reply to them (here translated as an Appendix), something Piaget rarely did. I summarize this affair with the Isaacs, pointing out the important empirical, theoretical, and philosophical issues separating them, many of which are still at issue in psychology, education, and philosophy today. (PsycInfo Database Record (c) 2025 APA, all rights reserved).