Jean Piaget.

 Jean Piaget (1896-1980) - an outstanding Swiss psychologist, logician, philosopher, one of the founders of genetic psychology. Piaget wrote more than 50 books, hundreds of articles. The breadth and versatility of his research as a psychologist is striking. Piaget studied ontogenetic development of logic, elementary physical and mathematical representations, morals. In the field of his attention were thinking, perception, imagination, memory, consciousness, will. In addition to psychology Piaget carried out research in the field of the biology of philosophy, logic, appealed to sociology and the history of science. 

 Jean Piaget studied and worked at the universities of Nevstal, Zurich, Paris, Lausanne, Geneva. Being a professor at the University of Geneva for many years, he was the director of the International Center for Genetic Epistemology at the University. In the research cycle on children, he developed a method of clinical conversation, and later the concept of cognitive development of children as a gradual process consisting of several stages (other names: the concept of the stage development of the psyche or the operational concept of intelligence). 

 Piaget believed that the development of intelligence is the basis, the core of mental development. He considered the principles of this concept to be key to understanding the evolution of thinking in different historical epochs and for various fields of knowledge; Has developed, on the basis of this provision, a special line of research, which he later called genetic epistemology. The theory, the first ideas and provisions of which were formulated by the author in the first half of the last century, remains topical and up to the present time is estimated by specialists as one of the most productive in laboratory-experimental and practical research. 

 Jean Piaget put forward the concept of the stadium development of the psyche. In his first works (Speech and the Thinking of the Child, 1923) he analyzed in detail the qualitative specifics of children's thinking. Using the method of clinical conversation, put forward, based on the judgments of the child, the proposition that the main distinguishing characteristic of his cognitive activity is egocentrism, by virtue of which he mixes subjective and objective, transfers his inner motives to the real connections of things. In the child's thinking, such features as magic (words and gestures are given the power of influencing external objects), animism (these subjects are endowed with consciousness and will), artificialism (phenomena of the surrounding world are considered manufactured by people for their purposes). These properties of thinking are reflected in the child's egocentric speech, which expresses the "logic of feelings" and does not perform a communicative function. Self-centeredness is overcome through socialization. 

 Later Piaget revised this view by developing a special logical system that allows describing the development of the child's psyche as a transformation of the actions (operations) performed by him. From the system of real external actions (sensorimotor intelligence), which are coordinated into integral systems and transformed into internal actions (Internalization), a logical-mathematical system of human cognition arises. To do this, actions must acquire special signs and turn into operations. The sensomotor and preoperative stages are replaced by the operational one. The interdependence of operations, their reversibility (for each operation there is an opposite or inverse operation) create stable and at the same time mobile integral structures. From the stage of concrete operations (which Piaget dated to the younger school age), thinking passes to the stage of formal logical operations, which ends by 15 years ("Psychology of the intellect," 1946). Principles of the operational concept of intelligence Piaget considered key to understanding the evolution of thinking in different historical epochs and for various fields of knowledge, having developed, on the basis of this provision, a special direction of research, which he called genetic epistemology.