The Developmental Psychology of Jean Piaget

By John H. Flavell

JEAN PIAGET—best known as developmental psychologist but also philosopher, logician, and educator—is one of the most remarkable figures in contemporary behavioral science. For more than forty years he and his associates have been constructing, in bits and pieces across an enormous bibliography, a broad and highly original theory of intellectual and perceptual development. Like Freudian theory, with which one is tempted to compare it in certain respects, Piaget’s theoretical system is a detailed and complicated one, not renderable in a few mathematical or verbal statements. Unlike Freudian theory, however, the system in its totality has not been widely assimilated by others. The major purpose of this book is to present an integrated overview of Piaget’s achievements, an overview sufficiently detailed to do justice to the complexity of his theory and the variety of his experimental contributions. This introductory chapter is intended to explain why a book on Piaget is desirable—or at least why it was written—and to summarize the plan or organization which the book will follow. In order to put these matters in context and to set the stage for a detailed description of Piaget’s system, it may be useful to examine briefly the man himself—the chronology of his life and achievements.

• Language: English
• Publisher: Barakaldo Books
• Release date: Apr 23, 2020
• ISBN: 9781839743672

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THE DEVELOPMENTAL PSYCHOLOGY OF JEAN PIAGET

BY

JOHN H. FLAVELLL

Table of Contents

Contents

Table of Contents 4

DEDICATION 5

Foreword 6

Preface 9

Introduction 11

THE MAN AND HIS WORK 12

THIS BOOK 19

Part One—THE THEORY 21

CHAPTER ONE—The Nature of the System 21

CHAPTER TWO—Basic Properties of Cognitive Functioning 41

CHAPTER THREE—The Sensory-Motor Period: General Development 79

CHAPTER FOUR—Special Sensory-Motor Evolutions and the Subperiod of Preoperational Thought 112

CHAPTER FIVE—Concrete Operations 136

CHAPTER SIX—Formal Operations and Perception 136

CHAPTER SEVEN—The Equilibrium Model, Genetic Epistemology, and General Summary 136

Part Two—THE EXPERIMENTS 136

CHAPTER EIGHT—The Early Work 136

CHAPTER NINE—Quantity, Logic, Number, Time, Movement, and Velocity 136

CHAPTER TEN—Space, Geometry, Chance, Adolescent Reasoning, and Perception 136

CHAPTER ELEVEN—Other Studies 136

Part Three—CRITIQUE 136

CHAPTER TWELVE—An Evaluation of the System 136

Bibliography 136

REQUEST FROM THE PUBLISHER 136

DEDICATION

To Ellie, Beth, and Jimmy

Foreword

IT IS BOTH A GREAT PLEASURE and a great honor to have been asked to write a foreword to the fine book you are about to read. A great pleasure, because it is a fine book, and hence there is no reluctance about praising its virtues and expressing my deepest appreciation to its author. But it is also a great honor, because this book seeks to present an integration of my own thought and work, and its appearance is an indication of esteem and confidence which I find deeply gratifying.

The goal which Professor Flavell has successfully achieved was a very difficult one and required a great deal of work, not only because I have written too much in the course of tackling too many different problems (moreover, only a portion of my books and very few of my articles have appeared in English) but above all because I am not an easy author; hence it must have required an immense effort at comprehension and intellectual empathy to have produced the clear and straightforward presentation that is found here. The principal source of difficulty, as Professor Flavell well knows, is the following. Naturalist and biologist by training, interested in epistemological problems, without ever having undertaken formal study (nor passed any examinations) in psychology, my most central concern has always been to determine the contributions of the person’s activities and the limiting aspects of the object in the process of acquiring knowledge. Fundamentally, it was the wish to resolve this problem using the experimental method that brought me into the field of developmental psychology. But it follows logically, since this point of view is not often held by psychologists in general—and even less by child psychologists—that those who read my work often find themselves confused. Thus a tremendous effort both in focusing and in reinterpreting had to be made to achieve a rendition of my work which is at once clear, well integrated, and fundamentally psychological in nature. Professor Flavell is certainly to be congratulated for having surmounted these difficulties in such an outstanding manner.

Professor Flavell has therefore done a most useful job and his book will certainly meet with the success it deserves. Its organization is a very well chosen one. Part One is given over to a presentation of the theoretical hypotheses. It was well to begin with these since the experiments, taken up in Part Two, were inspired by them. Finally, there is the critique (Part Three). It seems clear that Professor Flavell is more interested in the experiments than in the theory, which sometimes gives me the impression—perhaps not of having been misunderstood, but, if you will—of having been understood on certain issues more from without than from within. But since the great majority of readers are not likely to be primarily oriented toward the theory either, the emphasis he has chosen is probably the most useful one.

Likewise, I am highly pleased that Professor Flavell concluded his book with a critical section because it may lead the reader to take his positive comments about the system much more seriously than if he had blindly and uncritically gone along with me on all points.

On the other hand, although I have read these criticisms with much interest, it is difficult for me to find them all convincing. More specifically, I find it impossible at the present time to decide whether this highly significant critique is well-founded or not, because the psychology of operational structures is still only in its infancy and a final decision would have to hinge on a substantial body of research data yet to be gathered. When Professor Flavell argues that I have expended too much energy spinning an intricate theoretical spider web which does not catch enough of reality in it, I am reminded of my collaborators at the Center for Genetic Epistemology who are currently weaving considerable improvements into the web and I have the distinct impression that it is already catching more than flies. Likewise, he says that I do not clearly show how classes and relations synthesize into numbers; but this problem has been dealt with a number of times by Grize, Papert, Gréco, Inhelder, and myself (volumes XI, XIII, XV and XVII of Etudes d’Epistémologie Génétique) and both new formulations and new experimental results alike have already shown that the initial hypothesis was not such a wild venture after all. Professor Flavell also thinks, both that I have multiplied intellectual structures beyond necessity, and that the group structures in particular make neither as early nor as clear-cut and well-marked an entrance into cognitive life as I had indicated (owing to a lack of sufficient study of the identity and associativity properties of the group). But here again the research is far from being completed and its course so far does not support his criticism. And in any case it is apparent, from the current state of research evidence, that the formal operations which appear at twelve to fifteen years really do show novel structure; they are not called formal simply because of their late appearance.

In short, as regards the entire first set of criticisms—the general trend of which is that, in Professor Flavell’s opinion, there is too wide a gap between the facts I describe and the theories I invoke—it could be argued that the differences between us stem from the fact that his approach is perhaps too exclusively psychological and insufficiently epistemological while the converse is true for me. The solution is then to be sought in the field of interdisciplinary endeavor, and it is precisely because of this that our Center for Genetic Epistemology is designed to provide an opportunity for psychologists, logicians, and mathematicians to collaborate in the furtherance of such research.

As to the criticisms usually directed toward me regarding the qualitative method which we use in our intellectual development studies and regarding the role of language in the interpretation of data—criticisms on which Professor Flavell takes a comprehensive and moderate position—it must again be said that our research is far from completed and that all sorts of controls, both statistical and nonverbal, are currently in progress. It is important to understand clearly that in order to explore intellectual development in its creative spontaneity, without distorting it by a priori assumptions drawn from our experience with adult thought, it has been necessary to proceed in two phases: first, to unearth what is original and easily overlooked in the child’s successive stages of evolution, and to do this with methods, including verbal ones,{1} which are as free and flexible as possible; then, in a second phase, varied controls and more refined analyses become feasible. Indeed, we are currently trying the latter: for example, Dr. B. Inhelder has made use of the longitudinal method and more recently, with Dr. J. Bruner, has been trying to train logical operations by various means. The results of this study ought to prove extremely instructive.

The picture of our work which Professor Flavell provides extends only up to about 1960 and thus it cannot be considered the final word. But for the period of its coverage it is excellent, and our sympathetic spokesman and commentator—by his intellectual honesty, good will, and immense labor—has certainly earned our deepest gratitude.

JEAN PIAGET

Geneva

November 1962

Preface

THE MAJOR PURPOSE of the book is simply to speak clearly for Piaget to anyone who has reasons to listen to what he has to say and who has some background and sophistication in psychology or related disciplines. Who might such a reader be? He certainly might be a psychologist—budding or full-fledged, by vocation or by avocation, with child-developmental interests but also with other interests. He might also be a student of education, psychiatry, philosophy, sociology, and perhaps other fields; Piaget has done and said things which have implications well beyond the boundaries of psychology proper. The book has a secondary aim, important but nonetheless secondary: to evaluate Piaget’s work, both methodologically and in view of related work done by others. The first ten chapters serve the primary objective, while the last two, and particularly the last one, attempt to fulfill the secondary aim.

Like the objects of Piaget’s theory, this book began life as something quite other than what it eventually became. In 1955 I set out to write a graduate text on theories of child development. All was smooth sailing at first, and I judged that the whole project would be completed within a year. The theories I planned to write about appeared for the most part to be in just the kind of state which would make my task a quick and easy one. That is, their authors—or someone else—had already given a reasonably clear, detailed, and integrated account of them in some one or several publications each. All I had to do was to read these publications carefully and distill what I had read into a one-chapter summary of each theory, with perhaps a little restructuring and change of emphasis here and there.

One very important theory of child development—Piaget’s—turned out to be in a state so utterly recalcitrant to this plan that the plan itself finally unravelled. As I began to learn more about Piaget’s work, certain conclusions—initially resisted—eventually seemed inescapable. First, Piaget’s work obviously had to be an important segment of the proposed text if it was to be a text on developmental theories. Second, it became all too clear that it would take me several years to read enough Piaget to feel at all confident about constructing an accurate and properly balanced summary of his theory. More than that, I began to worry about what function even the best of one or two-chapter summaries could serve in the particular case of Piaget’s system. Might not such a summary have to be so compressed and elliptical that it could do little more than tease and frustrate any reader who had a really serious commitment to understand Piaget? He might read my summary, want more detail on most if not all points, and then have no recourse but to delve into the same dismaying expanse of scattered primary literature from which the summary was pieced together in the first place. So it was that the first plan was finally discarded for a second, of which the present volume is the outcome: write a book-length exposition of Piaget’s work alone, something which might serve at once as a guide to the multivolume original literature and as a backstop for any future digests of a briefer sort, e.g., as part of a text like the one which never got written!

Many minds, hands, and circumstances helped to make this book a reality, and I feel grateful to them all. I owe a special debt of thanks to Dr. Heinz Werner and others of his staff who were at Clark University during my graduate years; without their formative and enduring influences I might conceivably have written a book, but it almost certainly would not have been a book on Piaget. I feel likewise indebted to the late Dr. David Rapaport, whose incisive commentary on an early version of the manuscript profoundly influenced all subsequent writing. Also deserving of thanks for invaluable assistance in various forms are Drs. Jean Piaget, Bärbel Inhelder, Joachim F. Wohlwill, Peter H. Wolff, David Elkind, Edith Meyer Taylor, Crane Brinton, and David C. McClelland, the Psychology Editor for D. Van Nostrand Co., Inc. In addition, I should like to thank as a group the numberless faculty, graduate students, and others, both at the University of Rochester and elsewhere, who have helped to shape my thinking about Piaget over the past six years; collectively, they have played at least as important a ghost writer role as those singled out by name.

I am grateful to Social Science Research Council for a grant-in-aid which permitted me to work full time on the manuscript during the summer of 1961. Likewise, the University of Rochester has been most helpful in providing the needed time, intellectual atmosphere, and secretarial and library facilities over the years. I feel particularly indebted to Mrs. Marcia Macklin, who did all the typing. Surely the most competent secretary anyone ever had, she would without apparent effort read my wretched handwriting and mentally correct errors of substance as well as of spelling and punctuation, all the while typing at supersonic speed a manuscript which would later require almost no proofreading. This book is studded with quoted extracts from the works of Piaget and others, and I am most grateful to the individuals and publishing houses concerned for granting the necessary permissions. Thus, I wish to express my thanks to Dr. Jerome S. Bruner of Harvard University, Dr. Betsy W. Estes of the University of Kentucky, Dr. Alberta E. Siegal of Pennsylvania State University, Dr. Hans Aebli of the University of Saarland, and most especially, to Professors Jean Piaget and Bärbel Inhelder of the University of Geneva. Similarly, I am indebted to International Universities Press, Humanities Press, Basic Books, and W. W. Norton of New York and to The Journal Press of Provincetown; to Routledge and Kegan Paul, Tavistock Publications, and the British Psychological Society of London; to Presses Universitaires de France and Librairie Armand Colin of Paris; and to Delachaux et Niestlé of Neuchâtel and the Institut des Sciences de l’Education, University of Geneva.

Finally, I owe more than can be repaid to my wife, Ellie, who for years submitted cheerfully to the regimen of a morose husband when the book was going badly, and an absent one when it was going well.

JOHN H. FLAVELL

Rochester

December 1962

Introduction

JEAN PIAGET—best known as developmental psychologist but also philosopher, logician, and educator—is one of the most remarkable figures in contemporary behavioral science. For more than forty years he and his associates have been constructing, in bits and pieces across an enormous bibliography, a broad and highly original theory of intellectual and perceptual development.{2} Like Freudian theory, with which one is tempted to compare it in certain respects, Piaget’s theoretical system is a detailed and complicated one, not renderable in a few mathematical or verbal statements. Unlike Freudian theory, however, the system in its totality has not been widely assimilated by others. The major purpose of this book is to present an integrated overview of Piaget’s achievements, an overview sufficiently detailed to do justice to the complexity of his theory and the variety of his experimental contributions. This introductory chapter is intended to explain why a book on Piaget is desirable—or at least why it was written—and to summarize the plan or organization which the book will follow. In order to put these matters in context and to set the stage for a detailed description of Piaget’s system, it may be useful to examine briefly the man himself—the chronology of his life and achievements.

THE MAN AND HIS WORK

Jean Piaget was born on August 9, 1896, in Neuchâtel, Switzerland. From his own account he was always a studious child and, as is clear from his childhood achievements, a decidedly precocious one (1952d). He was early addicted to scientific studies, especially biological, and relates successive interests in mechanics, birds, fossils, and sea shells between the ages of seven and ten. As a portent of scholarly productivity to come, he published his first scientific paper at the age of ten—a one-page note on a partly albino sparrow he had observed in a public park. Shortly after, he contrived to serve after school hours as a volunteer laboratory assistant to the director of the local natural history museum, a malacologist or specialist in mollusks. During the four years he worked with the director, and in the ensuing years until 1930, he published about twenty-five papers on mollusks and related zoological matters, of which about twenty were in print before he reached the age of twenty-one. In his autobiography (1952d) Piaget tells of some humorous situations which resulted from his precocious productivity—for example, being offered (on the basis of his publications) the position of curator of the mollusk collection in the Geneva museum while still in secondary school! He pursued his formal higher education at the University of Neuchâtel, where he received his baccalaureate degree in 1915 and, following a dissertation on the mollusks of Valais, his doctorate in the natural sciences in 1918.

Throughout his adolescent and postadolescent years, Piaget read extensively in the fields of philosophy, religion, biology, sociology, and psychology, writing copious notes on a variety of problems. Some of the ideas developed during this period were prophetic of theoretical concepts fully elaborated only much later. First, from reading Bergson and others he became imbued with the idea that biology could be profitably brought to bear upon the epistemological problem, the problem of knowledge. But he felt that something else was needed to tie the two together and that philosophical analysis could not fulfill this role. In subsequent years, developmental psychology came to serve as the mediator, and a series of works on genetic epistemology was the final outcome (e.g., 1950b).

Second, he came to believe that external actions as well as thought processes admit of logical organization, that logic stems from a sort of spontaneous organization of acts. In his later work this notion seems to have been expressed in two related forms: first, that logical structures can be used to describe the organization of concrete, motor acts as well as that of symbolic, interiorized thought in the conventional sense (1954a); second, that all thought is essentially interiorized action, and it therefore follows that the organization of overt action and of inner thinking can be characterized in the same general way, can be placed on the same general continuum (1949b).

Finally, in this early, prepsychology period Piaget began formulating tentative views about totalities—Gestalt-like structures-of-the-whole—and about the possible kinds of equilibria which could characterize such structures. In any structure consisting of parts and of a whole containing these parts, he believed, there are only three possible forms of equilibrium: predominance of the parts with consequent deformations of the whole, predominance of the whole with consequent deformation of the parts, and reciprocal preservation of both whole and parts. Of these three, only the last is a good and stable equilibrium, the others deviating to a greater or lesser degree from this optimum. Piaget asserts (1952d) that even at that time he believed the third, stable form of equilibrium would characterize the organization of intelligence at its higher levels, and that the inferior forms would describe the structure of perception. It is interesting to note that, although almost all his writings from the early 1920’s reflect his preoccupation with problems of equilibrium, a really definitive statement on cognitive development as an equilibration process was not published until some forty-three years after these adolescent musings (1957c).

Upon receiving his doctorate in 1918, Piaget left Neuchâtel in search of training and experience in psychology. During the next year or two he wandered from place to place, not finding any problems in which he could really get involved. His activities included academic and practicum work at the laboratories of Wreschner and Lipps, at Bleuler’s psychiatric clinic, and at the Sorbonne. While studying at the latter, he was offered the opportunity to work in Binet’s laboratory at a Paris grade school. Dr. Simon, who was in charge of the laboratory, suggested that Piaget might try to standardize Burt’s reasoning tests on Parisian children. Although Piaget undertook this project without enthusiasm, his interest grew when he began the actual testing. He found himself becoming increasingly fascinated, not with the psychometric and normative aspects of the test data, but with the processes by which the child achieved his answers—especially his incorrect answers. By adapting psychiatric examining procedures he had acquired at Bleuler’s clinic and in practicum courses at the Sorbonne, he was soon using the clinical method which was later to become a kind of Piagetian trademark.

During the next two years Piaget continued to do research on the child’s responses to the Burt test questions and to other stimulus situations. He published the results of these first psychological experiments in a series of four articles (Piaget, 1921a, 1921b, 1922; Piaget and Rossello, 1921). One of the four was accepted for publication by Claparède at Geneva, editor of the Archives de Psychologie (1921a). Claparède, evidently impressed by this one sample of Piaget’s work, offered him the job of Director of Studies at the Institut J. J. Rousseau in Geneva. In this position he was to have ample research time and an almost completely free hand in developing his own program of child study. Piaget accepted the job on trial in 1921 and shortly after embarked on a series of studies which was to make him world-famous before he was thirty years old.

Piaget’s studies of the child’s language, causal reasoning, theories about everyday phenomena, moral judgment, etc., which were conducted in the period 1921-1925 are still his best-known experiments. They are described in his first five books (1926, 1928b, 1929c, 1930a, 1932){3} and in a less-known series of important articles (Piaget, 1923, 1924a, 1925a, 1927b, 1929b, 1931b; Krafft and Piaget, 1926; Margairaz and Piaget, 1925). In his autobiography (1952d) Piaget offers some interesting comments on this early, highly controversial work. It is clear that these studies were planned and conducted primarily with a view to providing data for the systematic and comprehensive epistemology which, since his youth, had been one of Piaget’s chief aims. That is, only for the naive reader were the famous five books simply interesting studies of child development. It is likewise clear that Piaget regarded them at the time as tentative and sketchy first drafts to be followed by a later more careful and comprehensive work. He was greatly surprised at the widespread attention they received and apparently a little dismayed that preliminary ideas should be treated by others as final statements of position. Finally, whatever shortcomings others have found in these studies, Piaget himself was in retrospect impressed by two essential ones. First of all, only an incomplete picture of cognitive structure and its development can be gained by the study of verbally expressed thought alone, that is, by questions put to the child in the absence of concrete manipulanda towards which the child’s responses can be directed. Yet the 1921-1923 work was almost wholly of this type. It was only later that Piaget became clearly aware, through the study of infants and the restudy of school-age children, of the necessity of distinguishing between logic-in-action, logic applied to concrete givens, and—the kind of behavior with which most of the early work dealt—logic applied to purely symbolic, verbal statements.{4} The second shortcoming, related to the first, was one of which Piaget was fully aware in the early 1920’s but could not remedy until later. In accord with his concern about part-whole relations mentioned earlier, he strove in vain to find structures-of-the-whole which would adequately describe logical operations. To be sure, the distinction between reversible and irreversible thought had already been made (e.g., 1924b, 1928b). However, the embedding of the reversibility concept into structures, such as the groupings of middle childhood, which could satisfactorily characterize the organization of operations only came later.

Two other developments of importance occurred during Piaget’s early incumbency at Geneva. First, he read the work of the Gestalt psychologists with great interest but reacted to it with mixed feelings (1952d). He was gratified to learn that others had succeeded in formulating a coherent theory concerning part-whole relationships, a theory which could be experimentally fruitful. However, he early became convinced that the Gestalt doctrine of non-additivity of parts within a whole (whole not equal to the sum of the parts), while correctly describing the structure of perception, did not apply to the equilibrium states which logical operations tend to achieve. To be sure, the specific nature of such equilibrium states and of the algebraic structures describing operations-in-equilibrium was not yet elaborated. At this time Piaget felt sure only that the Gestalt structures were not descriptive of logical operations; in later articles, he was to treat the relation of Gestalt theory to his own system more fully (1937a, 1954d, 1955a, 1955e).

A second and probably less important trend during the early 1920’s was what Anthony has called Piaget’s flirtation with psychoanalytic theory (Anthony, 1957). It is clear that Piaget read Freud (and Bleuler and Jung as well) and was particularly interested in the psychoanalytic conception of cognitive as opposed to affective functioning. Thus, there is an early attempt to relate the structure of unconscious adult thought, conscious adult thought, and the conscious thought of the child (1923). Similarly, he relied somewhat on Freudian theory in interpreting certain childhood myths in connection with his studies of artificialism (1929c). However, as his own studies proliferated and his own theory began to assume form and direction, references to psychoanalytic theory tended to drop out. Only rarely in later years did Piaget discuss psychoanalytic concepts in the context of his own work; and when he did, his treatment was more critical than sympathetic (e.g., 1951a). While it is certainly true that others have attempted to bring the two systems together (Anthony, 1956a, 1956b, 1957; Odier, 1956; Wolff, 1960), all the evidence suggests that Piaget himself has neither been profoundly influenced by Freud nor has tried to wed the two theories in any systematic way.

In 1923 Piaget was given a part-time appointment at the University of Neuchâtel and until 1929 divided his activities between Neuchâtel and Geneva. This four-year period was a busy one for him; he had a heavy teaching load in addition to his research work. The latter consisted principally of two lines of investigation. First, he did some preliminary work on the child’s reaction to changes in the shape of substances like clay, transformations which left weight and volume invariant. These investigations were important both because they led to more thorough studies of number and quantity later (Piaget, 1952b; Piaget and Inhelder, 1941) and because they were the first experiments with school-age, verbal subjects in which the shift to less exclusively verbal tasks becomes apparent.

But by far the most important new development in Piaget’s research during this period was a series of studies of intellectual development in infancy. With his wife’s assistance (Valentine Châtenay, a former student at the Institut J. J. Rousseau), he spent a great deal of time carefully observing both spontaneous and elicited behavior in his own infants. This work was reported in most complete form in three books (1951a, 1952c, 1954a) and one article (1927a) but is also summarized in many other places (e.g., 1937a, 1950a, 1957a). These investigations of infant behavior did more than simply provide Piaget with needed data on the early foundations of cognitive development. They also clarified his thinking on such fundamental problems as the specific nature of cognitive adaptation, and the relation between cognitive organization in the initial (presymbolic) sensory-motor period and in the subsequent periods of symbolic thought.

During the 1925-1929 period Piaget also concluded his work in the field of malacology. Although he never again did experimental studies in this area, a number of conceptions based on this work survived as integral parts of his psychological theories, most notably in his views on organism-environment relationships, both biological and psychological (1952c).

In 1929 Piaget returned to full-time status at the University of Geneva, becoming assistant director and later (in 1932) co-director of Institut J. J. Rousseau. During the 1929-1939 interval, Piaget became involved in two time-consuming administrative enterprises. First, the Institut, hitherto a private organization, became affiliated with the University of Geneva and Piaget was the prime mover in the reorganization which followed. Second, he became director of the Bureau International d’Education, a newly formed intergovernmental organization which has since become jointly affiliated with and sponsored by the International Office of Education and UNESCO. Although the job was time-consuming, it gave Piaget an opportunity to work towards a translation of developmental findings into educational practices. To this end Piaget and his co-workers have in the subsequent decades written extensively on the application of his theory to pedagogic methods (e.g., Piaget, 1951b, 1956; Aebli, 1951; Szeminska, 1935). In the post-war years, Piaget has remained active in educational affairs, both with the Swiss government and with UNESCO.

The period 1929-1939 saw a number of significant scientific activities. The teaching of a course on the history of scientific thought gave Piaget an excuse to pursue, more intensively than before, serious reading in the history of mathematics, physics, and biology. Although he had already done some writing in the area of genetic epistemology (1924a, 1925b, 1929a), the later three-volume work on this subject (1950b) seems largely to have been the fruit of his extensive reading and reflection during this period.

Another major achievement was the resumption, on a larger scale and with the help of Szeminska, Inhelder, and many other able assistants, of his earlier, preliminary studies of number and quantity concepts. Portions of this work were first described in several articles and monographs in the middle to late 1930’s (Piaget, 1937c; Piaget and Szeminska, 1939; Inhelder, 1936; Szeminska, 1935). In 1941 a fuller account was presented in two books (Piaget, 1952b; Piaget and Inhelder, 1941). This work was important for two reasons. It constituted a systematic redirection of attention towards the intellectual constructions of early through middle childhood after an interlude of several years of studying infant development. This renewed attack was to be more concerted and long-lasting than the famous work of the early 1920’s directed towards the same subject population. A wide variety of important areas of cognitive functioning were eventually studied: first, number and quantity; later, movement, velocity, time, space, measurement, probability, and logic. These studies are among the most interesting and ingenious that Piaget has made.

This series of studies of middle childhood was also important because it provided, as the earlier series did not, the sought-for insights into the structural properties of thought. The first structural model to come out of this work was the grouping (1937b, 1937c, 1937d).{5} A grouping is a hybrid logico-algebraic structure, possessing properties of both mathematical groups and lattices, which Piaget uses to describe cognitive structure in the 7-11-year-old. To be sure, there had been premonitions of this kind of model-building prior to this. Thus, Piaget had earlier described a group of spatial displacements in infancy (1954a) and had even earlier spoken of reversibility (a group property) as a major characteristic of cognition in the school years (1928b). The theoretical enterprise begun in 1937, however, was to be far more comprehensive and ambitious. In 1942 Piaget published a systematic and detailed description of the eight groupings which concrete operations form (1942a), and this was only the beginning. In 1949 there followed a more rigorous treatment of the same groupings plus a discourse on the structures which the sixteen binary interpropositional operations assume (1949a). Finally, three years later, Piaget wrote a thinner but even more difficult book on the structure of ternary interpropositional operations (1952a). It is difficult to overemphasize the importance of this shift towards logico-algebraic models for the form and content of Piaget’s writings in the last twenty years. Unlike the earlier work, experimental data since 1937 or so are systematically interpreted in terms of these structural models and these models serve to unify and permit comparisons among diverse findings in a way not possible in the earlier work. Also, it is fair to state that the search for structures became more than just this for Piaget. Evidently he also became interested in working out the myriad implicative possibilities of such structures for its own sake, as a logician would. At any rate, it is quite clear that he wanted to interest logicians as well as psychologists in his work, both in terms of its contributions to logic and in terms of its psychological implications (1949a, 1952a).

From 1940 on, Piaget has been engaged in a variety of activities. To begin with those of an administrative nature, he assumed the directorship of the Psychology Laboratory at Geneva in 1940. He continued to edit the Archives de Psychologie with Rey and Lambercier and became first president of the newly formed Swiss Society of Psychology, assuming in 1942 joint editorship of its journal, the Revue Suisse de Psychologie. He managed to give a lecture series in Paris in 1942 during the German occupation and delivered a briefer series after the war in Manchester, England. These lectures were subsequently published in English and constitute the principal summaries of Piaget’s system in that language by Piaget himself (1950a, 1957a). He received honorary degrees at various universities, including Harvard (at the 1936 tricentennial), Brussels, and the Sorbonne. Finally, as was mentioned, he remained active in the International Office of Education and, after it was organized, UNESCO.

As to scholarly activities, these fall into three major classes. Most of the studies of space, time, probability, movement, etc., were reported in a series of books (Piaget, 1946a, 1946b; Piaget and Inhelder, 1951, 1956, 1959; Piaget, Inhelder, and Szeminska, 1960). Two other volumes in the same vein are of particular importance. First, Inhelder published a book describing the use of the quantity tasks (conservation of mass, weight, and volume) as diagnostic instruments for testing intellectual ability in mental defectives (Inhelder, 1944). Later, with Piaget, she did a very interesting series of studies concerning adolescent thought (Inhelder and Piaget, 1958). This book, besides constituting the only major study of adolescent reasoning by the Piaget group, also contains a thorough theoretical analysis of concrete operations, formal operations, and the relations between the two.

The second major project by Piaget and his collaborators is a series of perception experiments begun in the early 1940’s and still in progress. These perception studies, reported in some forty articles, are more rigorous as regards methodology and reporting of quantitative data than are the studies of intellectual development. Put differently, these experiments would appear to the reader much more like conventional perception experiments than his intelligence studies would look like conventional studies of intellectual development. Again, quite unlike his theories of intellectual development, the perceptual theory which has emerged from these experiments is intended to be rigorously predictive of perceptual response, given known conditions of the perceptual field (e.g., Piaget, 1955 1956a; Piaget, Albertini, and Rossi, 1944-1945; Piaget, Vinh-Bang, and Matalon, 1958). Although the perception work has been to some extent an autonomous body of research in its own right in relation to the larger corpus of intellectual studies, the autonomy is far from complete. Piaget has continually tried to specify how perceptual structures compare with intellectual structures and to profit from the study of one in the study of the other (Piaget, 1951c, 1954b, 1955a, 1955e; Piaget and Morf, 1958a, 1958b).

The third major endeavor, like the second, is still very much in progress: a systematic theoretical and experimental attack on problems of genetic epistemology. In 1950 Piaget published a comprehensive three-volume work on this topic, focusing particular attention on the implications of developmental findings for epistemological problems in the fields of mathematics, physics, biology, psychology, and sociology (1950b). In 1955, aided by a grant from the Rockefeller Foundation, Piaget established at Geneva the Centre International d’Epistémologie Génétique. The Centre operates in the following way (Beth, Mays, and Piaget, 1957, pp. 1-11). Each year three distinguished scholars with epistemological interests are invited to come to Geneva for an academic year to collaborate with Geneva psychologists on certain delimited problems of a genetic epistemological nature. An attempt is made to pose problems which admit of experimental as well as theoretical study. At the end of the year, findings and conclusions are presented at a symposium composed of these scholars plus eight or nine others invited in from outside to participate in critical discussion and to help formulate plans for the next year. The results of a given year’s work are then published in a series of monographs (the one cited above, for example, is the first of four for the year 1955-1956).

At the time of this writing, Piaget’s scientific energies are principally directed towards the continuing perception studies and the work of the Centre International d’Epistémologie Génétique.{6} His return to the study of genetic epistemology was a long-overdue labor of love. As Piaget is fond of remarking (1950b, Vol. 1; 1952d), he had originally planned to spend only a few years studying children and then devote the remainder of his career to epistemological problems. It is difficult to predict what he would have accomplished if this carefully laid plan had actually been carried out. One thing is clear, however: this book would not have been written.

THIS BOOK

Why write a book summarizing Piaget’s system? For three reasons. First, his work appears to be of sufficient scope and stature to deserve recognition and understanding by a wide community of scholars interested in the ontogenesis of intelligence and perception. Second, there is every reason to believe that Piaget’s system has not, over the years, received anything like its due in this recognition and understanding. And finally, there is evidence of a burgeoning interest in the system, something of a contemporary Piaget revival.

As to the first, little need be said. Piaget’s work does in fact constitute a very substantial portion of the available theory and experimentation in the area of cognitive development, and anyone seriously interested in this area simply cannot afford to be ignorant of it.

As to the second point, there is good evidence for a definite, although irregular, pattern of underassimilation of the system, especially in the English-speaking professional world. The pattern appears to be this. There is ample enough citation and discussion of Piaget’s early studies on language and thought, moral judgment, etc.—the work reported in his first five books (1926, 1928b, 1929c, 1930a, 1932). But the bulk of Piaget’s contributions came later, and most of this bulk has not yet become part of the living literature. Indices of low assimilation are everywhere apparent. One index is latency of translation. To take two examples: Piaget’s basic work on infancy was published in French in 1937 and translated into English in 1952 (Piaget, 1952c); his studies of the child’s measurement operations first appeared in 1948 and remained untranslated until 1960 (Piaget, Inhelder, and Szeminska, 1960). Another index is citation by secondary sources in the child-development field. A 1295-page manual of child psychology (Carmichael, 1954) refers only to Piaget’s first five books. Jersild’s child psychology text cites only three of these five (1954), and his book on adolescence cites no Piaget work at all (1957). And two source books on cognition (Vinacke, 1952; Johnson, 1955) also follow the pattern of referring exclusively to the early studies.

As for the rising surge of interest in the system, there is again an abundance of clues. For instance, the pace of translation has become brisker. There were no Piaget books translated into English between 1933 and 1949, but there have been nine or more since 1950, with several others said to be on the way. Similarly, the number of Piaget-relevant experiments by workers outside the Geneva circle has definitely accelerated (see Chapter 11).

This is surely a happy combination of circumstances from the standpoint of someone having in mind the writing of a book on Piaget: here is a body of work of indisputable import in which there is currently a lively and growing interest, and at the same time one which has not generally been either well or widely understood. But it must also appear to be a rather puzzling combination. In particular, one might ask why there is such an apparent discrepancy between the volume and significance of Piaget’s output and the relatively meager extent to which it has been taken up by the rest of the field. This is an important question to consider here, because the aim and organization of the book partly hinge on the answer.

Consider what is in store for anyone who sets out to master Piaget’s system. He will soon discover that the pertinent theory and experiments are distributed across more than twenty-five books and a hundred and fifty articles (and some of the latter are nearly book length). He will also discover that most of the available publications which summarize more than limited portions of the system are too brief on the one hand, and either too elementary or too difficult on the other, to be of more than limited help to anyone who has not already read the original sources. When, reluctantly, he decides he must plough through the primary literature, he will be confronted with still more difficulties. Very few of the articles are available in English translation; many of the books are, but by no means all. Ph.D. language examinations notwithstanding, this is likely to be a problem. Furthermore, most of Piaget’s writings are very difficult to read and understand, in French or in English. For one thing, there are many new and unfamiliar theoretical concepts, and they intertwine with one another in complicated ways to make the total theoretical structure. In addition, much of the theoretical content requires some sophistication in mathematics, logic, and epistemology. It is not easy to assess the extent to which this characteristic of Piaget’s writings constitutes an obstacle, either intellectual or emotional, for the average behavioral scientist. Even with the requisite background, he may be repelled by a system which so liberally mixes mathematics and philosophy with developmental psychology. And there are still other hurdles, difficult to convey without having already described the system (they are discussed in Chapter 12, however).

It is small wonder, then, that Piaget’s work has been underassimilated. And the fact and causes of this underassimilation help to dictate the way in which this book was conceived and written. Thus, its primary aim is to communicate and inform, not to criticize and evaluate. Accordingly, eleven of its twelve chapters are primarily expository, and only one principally critical-evaluative. The majority of the expository chapters deal with theory rather than experiments, because we think it is Piaget’s theory, rather than his experiments, which people find especially difficult to grasp.

Hence, the organization of the book is as follows. There are three parts. The first attempts an integrated and detailed summary of Piaget’s theory, and consists of Chapters 1-7. The second part, comprising Chapters 8-11, is devoted to experiments: Piaget’s own in Chapters 8-10, and Piaget’s plus other relevant studies in Chapter 11. Part III consists of one long chapter which tries to evaluate the system, both theory and experiments. Piaget’s system does not of course neatly divide itself into theory and experiments for the convenience of his Boswell. For this reason, Part I necessarily makes considerable reference to experimental work. In fact, in the case of sensory-motor and early conceptual development, it seemed to make sense to include almost all the experimental material in the first section. Similarly, the experimental chapters are far from devoid of theoretical discussion. The result of such overlapping is naturally a good deal of repetition—of both concepts and experimental findings. But if the writer’s own past (and continuing) difficulties in trying to understand Piaget are any basis for judgment, a certain measure of redundancy may be a blessing for the reader.

Part One—THE THEORY

CHAPTER ONE—The Nature of the System

A NUMBER of facts about Piaget’s work lie not so much in the system as about and around it. Information of this kind, of which only a part can be termed metatheory in the strict sense, is primarily orientative: it helps to place the system in the context of other systems, both similar and different. This chapter offers such peripheral and perspective-giving information.

First and most basic will be a discussion of Piaget’s scientific aims: precisely what he has attempted to study and what he has not attempted to study. A description of Piaget’s methodology—or methodologies—follows this. Since some of his experimental methods have come under critical attack, it will be especially important to describe these with some care. The third and final section is more difficult to define. It will include what might be called a personality profile of Piaget’s theoretical writings—a description of idiosyncrasies of the system, of characteristics of the work and its written presentation which make it uniquely a Piaget production.

In discussing these things—scientific aims, methodologies, and idiosyncrasies of the system—a lot of important theoretical and experimental content will be sketched much too briefly and superficially for complete understanding; most of this content will, however, be taken up again in detail in subsequent chapters. This chapter means to convey a preliminary and global image of the system, rather than a detailed mapping.

SCIENTIFIC AIMS

It is possible to give a rough definition of Piaget’s principal scientific concerns in a single sentence: he is primarily interested in the theoretical and experimental investigation of the qualitative development of intellectual structures. The pertinent words and phrases of this definition need examination and qualification.

Intelligence

A persistent and overriding interest in the area of intelligence is a salient feature distinguishing Piaget’s work from that of most child psychologists. To be sure, he has been and is interested in other areas, most notably perception, but also moral attitudes and other value systems (Piaget, 1932, 1934c; Inhelder and Piaget, 1958) and even motivation (1952c). As for perception, much of its value as an object of study for Piaget lies in the fact that it can be compared and contrasted with intelligence. Values and attitudes are seen as cognitive systems imbued in the later stages of development with the same formal organization as more unambiguously intellectual achievements (1954c). As Chapter 2 will show, motivation is treated almost exclusively in terms of motivation to intellectual adaptation. Moreover, the motives seen as most important are thought to be intrinsic to intellectual functioning itself and can at least approximately be conveyed by such terms as exploratory drive, drive to mastery, etc.; conventional bodily needs as motivators, the perennial favorites of learning theory, are given short shrift in Piaget’s system. Finally, his interests in education, logic, and epistemology are almost exclusively intelligence-oriented.

Development

Piaget is also and just as fundamentally a developmental psychologist in the great tradition of Hall, Stern, Baldwin, the Bühlers, Binet, Werner, and the rest. He firmly believes that the study of ontogenetic change is a valuable undertaking in its own right. Even more, he is convinced that adult human behavior cannot be fully understood without a developmental perspective and deplores what he sees to be an unfortunate contemporary hiatus between child psychologists and those who study only adults (1957b, pp. 18-19). The addition of the genetic dimension, as he calls it, does more than simply give historical status to adult cognition; it makes possible, he believes, at least tentative solutions to age-old epistemological problems, especially those concerned with the ontogenetic precursors of certain important classes of cognitions.

We need to make clear precisely what Piaget’s developmental approach—the study of the genetic dimension—does and does not involve. It does involve the careful description and theoretical analysis of successive ontogenetic states in a given culture. Thus behavior change from less to more advanced functioning is the primary datum. Further, it involves painstaking comparisons among these successive states; the dominant characteristics of a given state are described in terms of states preceding and states following. It is characteristically not concerned with any systematic exploration of other independent variables which may temporally accelerate or retard the appearance of the behavior studied. In this almost exclusive preoccupation with age changes per se, Piaget is poles apart from many contemporary child psychologists (see Chapters 11 and 12).

Structure, Function and Content

A third important feature of Piaget’s system is a particular bent towards studying the structure of developing intelligence, as opposed to its function and content. Piaget has made distinctions among these three, and especially between the first two, in a number of places (1928a, 1931a, 1931c, 1952c).

In speaking of content, he refers to raw, uninterpreted behavioral data themselves. Thus, when one of Piaget’s subjects asserts that one object sinks because it is heavy and another sinks because it is light (1930a), or behaves as though time were a function of the distance an object travelled but not of its velocity (1946a), we witness behavioral content. So also are the substantive, external aspects of earlier sensory-motor behavior, such as the child’s capacity to make detours, to estimate distances visually, etc. (1954a).

By function, on the other hand, Piaget refers to those broad characteristics of intelligent activity which hold true for all ages and which virtually define the very essence of intelligent behavior. As will be seen in Chapter 2, intelligent activity is always an active, organized process of assimilating the new to the old and of accommodating the old to the new. Intellectual content will vary enormously from age to age in ontogenetic development, yet the general functional properties of the adaptational process remain the same.

Interposed between function and content, Piaget postulates the existence of cognitive structures. Structure, like content and unlike function, does indeed change with age, and these developmental changes constitute the major object of study for Piaget. What are structures in Piaget’s system? They are the organizational properties of intelligence, organizations created through functioning and inferable from the behavioral contents whose nature they determine. As such, Piaget speaks of them as mediators interposed between the invariant functions on the one hand and the variegated behavioral contents on the other (1928a).

In the above example of objects sinking in water for two opposed reasons, certain structural properties can be said to mediate or be responsible for this content. First, the child is phenomenistic in the sense that his cognitive structure is so organized that the surface appearances of things are overattended to; his thought is dominated by the environmental properties which strike him first and most vividly—in this case the lightness or heaviness of the object. Second, he fails to relate in a logical way successive cognitive impressions; thus, heaviness and lightness are successively invoked as explanatory principles with no thought to the contradiction involved, as though the need to reconcile opposing impressions were not a characteristic of his cognitive structure. These are structural properties in the sense that they determine precisely what will and will not result when a given cognizing organism attempts to adapt to a given set of external events. To use a simple and somewhat imprecise capsule definition, function is concerned with the manner in which any organism makes cognitive progress; content refers to the external behavior which tells us that functioning has occurred; and structure refers to the inferred organizational properties which explain why this content rather than some other content has emerged.

The different structural characteristics posited for the various developmental levels are in large part the subject matter of the following chapters and are not specified here. Suffice it to say that Piaget’s career can be divided into two rough eras with respect to the way structures are described. During the first twenty years or so, structures were defined primarily in verbal, intuitional terms. The structural properties of behavior towards sinking objects, in the example given above, were described in such terms, e.g., expressions like phenomenistic, lack of need to reconcile opposing impressions, etc. There are a large number of concepts of this type, especially in the earlier work: egocentrism, syncretism, juxtaposition, reversibility, predicative thinking, realism, animism, artificialism, dynamism, precausality, transductive reasoning. Beginning with the introduction of the group of displacements in the early 1930’s (1954a) and of the grouping a few years later (1937b, 1942a), structural characteristics tend more and more to be framed in terms of logical algebra and equilibrium theory. This tendency to substitute mathematical for verbal terminology is not to be taken as a rejection of earlier interpretations in favor of new and different ones. Rather, it is an attempt to discover (or even invent, whenever necessary) mathematical structures which express the essence of these verbally given organizational properties. For example, and to anticipate a bit, a child of eight who possesses the grouping structure will, by implication from the structure, show reversibility of thought, a relative lack of egocentrism, a capacity for synthesizing rather than simply juxtaposing data, and a number of other characteristics.

Finally, it should be said that Piaget’s concern with structure as opposed to content and function is by no means absolute. It can hardly be said that he has ignored function and content. As regards function, one of the distinguishing characteristics of his theory has been an attempt to isolate the abstract properties of intelligence-in-action which hold for all sentient organisms. These properties—organization and the two components of adaptation mentioned above, assimilation and accommodation—are called functional invariants (1952c, p. 4). As Chapter 2 shows, an examination of these functional invariants is crucial in any discussion of structural change. Similarly, the content of developmental acquisitions is taken to be important otherwise than simply as evidence for structural properties. To take one example, Piaget has made suggestions for the teaching of elementary mathematics on the basis of content aspects of the development of number in children (1956). And the content aspects of Piaget’s studies tend in themselves to be interesting to the average reader; they would scarcely be less than interesting to Piaget himself.

Qualitative Stages

The fourth and final key word in the definition of Piaget’s aims is qualitative. He is interested in the qualitative characteristics of development. His concern with structure versus content betrays this, since structural changes are in their essence qualitative in nature. In Piaget’s system, the panorama of changing structures in the course of development is conceptually partitioned into stages whose qualitative similarities and differences serve as conceptual landmarks in trying to grasp the process. Piaget and Inhelder have tried to specify some of the criterial aspects of the stage concept (Piaget, 1955d; Tanner and Inhelder, 1956).

THE REALITY OF STAGES

In order to posit a succession of developmental stages for a given behavior domain, they argue, the behavioral changes in the domain must first of all be susceptible of such a breakdown. That is, if behavior simply becomes better and better in a completely continuous way with no readily discernible qualitative changes in the process, if earlier behavior patterns do not naturally seem to segregate themselves in a qualitative sense from later clusters, any abstraction of stages becomes meaningless and arbitrary. Although there are some discriminable differences between earlier and later perceptual structures, Piaget feels that these are not sufficient to warrant a stage-by-stage analysis of perceptual development, and he does not offer one. For intellectual structure, on the other hand, it is suggested that such an analysis is both justified and fruitful; intellectual development does show sufficient qualitative heterogeneity, enough "coupures naturelles bien nettes" (1955d, p. 83) to permit such analysis.

INVARIANT SEQUENCE OF STAGES

Granted that a developmental series is amenable to stage description, the stages abstracted must possess certain properties. First, they must emerge in development in an unchanging and constant order or sequence; a stage A must, by this criterion, appear in every child before stage B occurs. If the behaviors which define the two stages do not occur in a constant ontogenetic sequence, it is erroneous to speak of them as stages. Although sequence is taken as invariant, the age at which a given stage appears may of course vary considerably (1928a). Put otherwise, the series of stages form an ordinal but not an interval scale. Thus, Piaget readily admits that all manner of variables may affect the chronological age at which a given stage of functioning is dominant in a given child: intelligence, previous experience, the culture in which the child lives, etc. For this reason, he cautions against an overliteral identification of stage with age and asserts that his own findings give rough estimates at best of the mean ages at which various stages are achieved in the cultural milieu from which his subjects were drawn. Furthermore, as a corollary to the foregoing, of course not all individuals need achieve the final stages of development. In this connection, for example, Inhelder has demonstrated arrested developments in mentally deficient subjects (Inhelder, 1944). Piaget has also for a long time freely conceded that not all normal adults, even within one culture, end up at a common genetic level; adults will show adult thought only in those content areas in which they have been socialized (1928a). In other words, as will be shown in the discussion of décalages below, a given individual need not be able to function at the same structural level for all tasks.

HIERARCHICAL RELATIONS BETWEEN SUCCESSIVE STAGES

A second essential characteristic of true stages is that the structures defining earlier stages become integrated or incorporated into those of the stages following. For instance, the stage of formal operations—the final stage in Piaget’s developmental system—involves cognitive activities which are performed upon the concrete operations elaborated in the stage just preceding. Concrete operations must precede formal operations in the temporal series, logically as well as psychologically, since the constitution of the former is absolutely necessary to the activation of the latter.

INTEGRATED CHARACTER OF STAGES

A third and most crucial criterion is that the structural properties which define a given stage must form an integrated whole. Piaget refers to this kind of totality as a structure d’ensemble. That is, once structural properties reach an equilibrium state (see below), they characteristically show a high degree of interdependence, as though they formed part processes within a strong total system. Or better, the existence of the equilibrium condition implies this interdependence (1957c). This unified and organized character of structures makes it possible to define the totality which they form, e.g., a grouping, a group of four transformations, etc., and then to interpret a broad and diverse range of seemingly unrelated behaviors in terms of this underlying structural whole. As Piaget’s biography has shown, his lifelong professional goal has been to find those structural wholes, of great abstraction and generality, which correctly identify the essence of organized intelligence at its various levels.

PREPARATION AND ACHIEVEMENT PERIODS

A stage is further characterized as containing an initial period of preparation and a final period of achievement. In the preparation period, the structures which define the stage are in