(August 9, 1896-September 16, 1980)
Swiss Biologist and Child Psychologist



  • Ph.D. in the Natural Sciences, University of Neuchâtel, Switzerland (1918)
  • Postdoctoral studies in psychoanalysis, University of Zurich (Winter, 1918-1919)


  • Publishes his first biology paper (on the albino sparrow) at age 10 (1907)
  • Théodore Simon asks him to standardize Cyril Burt’s intelligence tests with Parisian children (1920)
  • Publishes his first article on the psychology of intelligence (1921)
  • Research Director, Institut Jean-Jacques Rousseau, Geneva (1921-1925)
  • Professor of psychology, sociology and history of science, University of Neuchâtel, Switzerland (1925-1929)
  • Professor of the History of Scientific Thought, University of Geneva (1929-1939)
  • Director of the International Bureau of Education, Geneva (1929-1967)
  • Director, Institute of Educational Sciences, University of Geneva (1932-1971)
  • Professor of Psychology and Sociology, University of Lausanne, Switzerland (1938-1951)
  • Professor of Sociology, University of Geneva (1939-1952)
  • Chair of Experimental Psychology, University of Geneva (1940-1971)
  • Professor of Genetic Psychology, the Sorbonne, Paris (1952-1963)
  • Founder/Director of the International Center for Genetic Epistemology, Geneva (1955-1980)
  • Founder, School of Sciences, University of Geneva (1956)
  • Emeritus Professor, University of Geneva (1971-1980)
  • Ph.D. in the Natural Sciences, University of Neuchâtel, Switzerland (1918)
  • Postdoctoral studies in psychoanalysis, University of Zurich (Winter, 1918-1919)

Definition of Intelligence

“Intelligence is an adaptation…To say that intelligence is a particular instance of biological adaptation is thus to suppose that it is essentially an organization and that its function is to structure the universe just as the organism structures its immediate environment” (Piaget, 1963, pp. 3-4).

“Intelligence is assimilation to the extent that it incorporates all the given data of experience within its framework…There can be no doubt either, that mental life is also accommodation to the environment. Assimilation can never be pure because by incorporating new elements into its earlier schemata the intelligence constantly modifies the latter in order to adjust them to new elements” (Piaget, 1963, p. 6-7).

Major Contributions

  • The theory of Genetic Epistemology*

Ideas and Interests

Jean Piaget was a precocious child who demonstrated a keen interest in animal life and an encyclopedic knowledge of biology and taxonomy. When he was ten years old, he began volunteering at the Neuchâtel Museum of Natural History. The museum’s director, the seventy year-old naturalist Paul Godet, took him on as his assistant and apprentice, and paid him for his work by giving him rare specimens for his personal collection (Vidal, 1994). Piaget continued to work at the museum for four years, and his interest in the natural sciences continued to grow. His professional accomplishments in this area were numerous, beginning at age ten when he published a paper on the albino sparrow, and culminating with a doctoral thesis on the classification of mollusks when he was twenty-one.

After completing his Ph.D., Piaget spent several months studying psychoanalysis at the University of Zurich. He was a promising student, and his contemporaries believed that he would eventually make important contributions to this field (Vidal, 1994). However, a serendipitous opportunity presented itself, and Piaget soon found himself working for Théodore Simon, co-author of the Binet-Simon intelligence scale. Simon placed him in Binet’s laboratory, and set him to work standardizing Cyril Burt’s reasoning tests on Parisian children.

Piaget thought that the standardizing task was dull, and he never finished it. However, his clinical interactions with the children were not without interest. He began to notice that children of similar ages made similar types of mistakes, and it occurred to him that Simon, Binet and Burt might be asking the wrong question: Perhaps the key to understanding human intellectual development is not in what children get wrong, but how they get it wrong. It was clear to Piaget that childish reasoning is not merely less accurate than adult reasoning; it is qualitatively different (Wadsworth 1996). From this point forward, Piaget dedicated himself to answering the question “How does knowledge grow?”

Piaget eventually came to believe that intelligence is a form of adaptation, wherein knowledge is constructed by each individual through the two complementary processes of assimilation and accommodation. He theorized that as children interact with their physical and social environments, they organize information into groups of interrelated ideas called “schemes“. When children encounter something new, they must either assimilate it into an existing scheme or create an entirely new scheme to deal with it (Wadsworth 1996).

Piaget also believed that intellectual development occurs in four distinct stages. The sensorimotor stage begins at birth, and lasts until the child is approximately two years old. At this stage, the child cannot form mental representations of objects that are outside his immediate view, so his intelligence develops through his motor interactions with his environment. The preoperational stage typically lasts until the child is 6 or 7. According to Piaget, this is the stage where true “thought” emerges. Preoperational children are able to make mental representations of unseen objects, but they cannot use deductive reasoning. The concrete operations stage follows, and lasts until the child is 11 or 12. Concrete operational children are able to use deductive reasoning, demonstrate conservation of number, and can differentiate their perspective from that of other people. Formal operations is the final stage. Its most salient feature is the ability to think abstractly.

A central tenet of Piaget’s Genetic Epistemology is that increasingly complex intellectual processes are built on the primitive foundations laid in earlier stages of development. An infant’s physical explorations of his environment form the basis for the mental representations he develops as a preoperational child, and so on. Another important principle of Piaget’s stage theory is that there are genetic constraints inherent in the human organism-You can challenge a child to confront new ideas, but you cannot necessarily “teach” him out of one stage and into another. Moreover, a child cannot build new, increasingly complex schemes without interacting with his environment; nature and nurture are inexorably linked. As Piaget put it:

Intelligence does not by any means appear at once derived from mental development, like a higher mechanism, and radically distinct from those which have preceded it. Intelligence presents, on the contrary, a remarkable continuity with the acquired or even inborn processes on which it depends and at the same time makes use of. (Piaget, 1963, p. 21)

Attempts have been made to correlate performance on Piagetian conservation tasks with standardized intelligence test scores, and the results have been mixed. (Kirk, 1977). Ultimately, an intelligence test built on a Piagetian framework would have to function very differently from intelligence tests like the Wechsler or the Stanford-Binet. In addition to recording a child’s correct and incorrect responses, the test administrator would also have to ask the child to explain why he answered in a given way. Piaget suggested that one way to reconcile these two approaches would be to adopt a method clinique, whereby a traditional intelligence test could serve as the basis for a clinical interview (Elkind, 1969).

*Epistemology: n. a branch of philosophy that investigates the origin, nature, methods, and limits of human knowledge.

Selected Publications

Piaget, J. (1936, 1963) The origins of intelligence in children. New York: W.W. Norton & Company, Inc.

Piaget, J. (1954, 1981). Intelligence and affectivity: Their relationship during child development. Palo Alto, CA: Annual Review, Inc.

Piaget, J. (1963, 2001). The psychology of intelligence. New York: Routledge.

Piaget, J. (1970). Genetic epistemology. New York: W.W. Norton & Company.

Piaget, J. (1972). Intellectual evolution from adolescence to adulthood. Human Development, 15(1), 1-12.

Piaget, J. (1973). Memory and intelligence: New York: BasicBooks.

Piaget, J. (1974, 1980). Adaptation and intelligence: Organic selection and phenocopy. Chicago: University of Chicago Press.


Costello, R.B. (Ed.) (1992). Random House Webster’s college dictionary. New York: Random House.

Kirk, L (1977). Maternal and subcultural correlates of cognitive growth rate: The GA pattern. IN P.R. Dasen (Ed.), Piagetian psychology: Cross-cultural contributions. New York: Gardner Press.

Elkind, David. (1969). Pagetian and psychometric conceptions of intelligence. Harvard Educational Review, 39(2), 319-337.

Piaget, J. (1936, 1963) The origins of intelligence in children. New York: W.W. Norton & Company, Inc.

Vidal, F. (1994). Piaget before Piaget. Cambridge: Harvard University Press.

Wadsworth, B.J. (1996). Piaget’s theory of cognitive and affective development: White Plains, NY: Longman.