It is difficult to decide where to begin any analysis of Piaget's system because there is an inbuilt interdependence of concepts which makes virtually any aspect a justifiable starting-point. We have decided to start with equilibrium, and what might be called its structural expression, reversibility, and to follow this with a discussion of the component aspects of the model. We have chosen this starting-point since Piaget sees equilibrium as the target of the process he calls equilibration. This term encapsulates all the interactional relationships between cognising subject and cognised milieu, or total environment, in which the subject exists and grows. Also, as the target of the cognising process, equilibrium is the principal objective determining the system as a whole. The best order for a critical exposition of Piaget's system is, of course, largely a matter of opinion. A case could be made, especially in respect of the definitive The Development of Thought, for doing it almost any way round. We, however, propose to 'move outwards', as it were, from the generalised notion of stability expressed in the most mature stage of the individual's develop-

An image of an active organism which both selects and incorporates stimuli in a manner determined by its structure, while at the same time adapting its structure to the stimuli, emerged from these early studies as a ready-made model for cognitive development. In Piaget's view cognitive development must have its roots firmly planted in biological growth, and basic principles valid for the former are to be found only among those which are true of the latter. (Flavell, 1963, p. 36)


For Piaget, the one-time biologist, intelligence can be meaningfully considered only as an extension of certain fundamental biological characteristics, fundamental in the sense that they obtain wherever life obtains. (It is indicative of Piaget's biological orientation toward matters intellectual that he sometimes refers to cognitive development as 'mental embryology', e.g., 1947, p. 143.) Intellectual functioning is a special form of biological activity and, as such, possesses important attributes in common with the parent activities from which it derives. (pp.41-2)

In deriving intelligence from what Flavell calls a 'biological substrate', Piaget shows no particular originality. Ever since the publication of the Origin of Species, Mendelian genetics, and still more with modern advances in molecular biology and neurophysiology, there has been a very strong tendency in biological science to make mentality dependent on the physically organic, and sometimes wholly indentified with it. Within such a

It is not that such problems are absent from the biologically oriented schools of psychology. But they tend to be buried beneath technicalities and/or jargon in the manner referred to in Chapter 1. Piaget is distinguishable precisely because he rejects such an identification. Dealing with thought-processes and knowledge, which he claims are both rooted in, and 'isomorphic' to, biology, he has to reconcile temporal, or evolutionary, change with an interpretation of the stability of things which is wholly tied to non-temporal, logically closed structures. While there is clearly a new dimension of difficulty in Genetic Epistemology over and above the problems of the dynamics of growth in biology itself, there are also difficulties in this latter area which prompt the question, does biology really offer the secure base for the understanding of mental growth that Piaget's system implies?