Before games are played in common, no rules in the proper sense can come into existence. Regularities and ritualized schemas are already there, but t… - Jean Piaget

As far as the game of marbles is concerned, there is therefore no contradiction between the egocentric practice of games and the mystical respect entertained for rules. This respect is the mark of a mentality fashioned, not by free cooperation between equals, but by adult constraint.

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.

The individual acts only if he experiences a need, i.e., if the equilibrium between the environment and the organism is momentarily upset, and action tends to re-establish the equilibrium, i.e., to re-adapt the organism (Claparède).