ABSTRACT
In his critique of linguistic philosophy Gellner assigns to philosophy a vital role: 'fundamental thinking aimed at making explicit our picture of the world, our various modes of knowing and forms of activity, and introducing new vistas and at assessing basic alternatives'. This describes the role that philosophical thinking has played in this book. Piaget's theory has been subjected to a critical examination not from the point of view of questioning the empirical details of his theory from the basis of empirical tests but from the point of view of making explicit the picture of the knowing subject at the root of Piaget's theory and assessing that picture.
