Originally published in 1975, this volume (3 of 4) presents an expanded model of certain deductive abilities in children and adults. A partial explanation of the growth of these abilities was suggested in Volume 2 of this series, and it is amplified here, both with regard to propositional logic and the logic of class inclusion. A new methodology is employed, the issue of the effect of content in deductive reasoning is covered, and developmental questions are reformulated. Although only data from experiments with adolescents are presented here, the volume sets the stage for potentially...

Originally published in 1976, this fourth and final volume in a series that met with critical acclaim is concerned with a certain kind of answer to the question "What distinguishes the concepts that are a natural part of human languages from those that are merely expressible in language?" The kind of answers contemplated rely on formal properties of the logics that overlay the two sorts of concepts. The author presents a substantive theory of natural concepts which helps to make concrete the methodological proposals. In order to make the theory more manageable, it is restricted to...

Originally published in 1974, a wide and interesting set of intellectual abilities in children are examined here. Volume 1 of 4 (Organization of Length and Class Concepts: Empirical Consequences of a Piagetian Formalism) converts an axiomatization of classes and asymmetrical relationships (proper to Piaget’s discipline of Genetic Epistemology) into a model of the development of these notions in children. Here may be one of the only attempts to derive predictive consequences from the more philosophically oriented writings of the Genevan School.

Originally published in 1974, the second volume of four (Logical Inference: Underlying Operations) provides a process-model for the solution of certain syllogistic reasoning problems. Testable predictions of the model are easily derived, and the available evidence supports the model’s description of the real-time mental steps mediating these logical abilities. A theory of development, connected to the model, makes these volumes all the more important for cognitive, developmental, and educational psychologists, as well as educators and linguists.