"Gustavo Solivellas dice: "Si un individuo es pasivo intelectualmente, no conseguirá ser libre moralmente" (Jean Piaget)" - Jean Piaget

Knowing reality means constructing systems of transformations that correspond, more or less adequately, to reality. They are more or less isomorphic to transformations of reality. The transformational structures of which knowledge consists are not copies of the transformations in reality; they are simply possible isomorphic models among which experience can enable us to choose. Knowledge, then, is a system of transformations that become progressively adequate.

Piaget is also concerned with attempts of Maine de Biran, Bergson, Sartre, and Merleau-Ponty to construct a philosophical psychology as opposed to a scientific empirical psychology. He believes that the difference between philosophical psychology and scientific psychology lies neither in the fact that the former concerns itself with “essences” (Husserl), with “irrationality” (Sartre), nor in its use of introspection. He sees the difference as being one rather of method: philosophical psychology neglects objective verification and grounds itself in subjectivity, although claiming to arrive at objective knowledge through intuition.

Play is the work of childhood.