The original French edition, La Psychologie de l’intelligence, was published by Armand Colin in 1947 and was based on lectures Piaget had delivered at the Collège de France in 1942.

(First pages and selected excerpts)

CHAPTER I
INTELLIGENCE AND BIOLOGICAL ADAPTATION


Every psychological explanation eventually turns either toward biology or toward logic — or toward sociology, which ultimately raises many of the same questions.

For some thinkers, mental phenomena can be understood only in relation to the organism. This approach is clearly necessary when we study elementary functions such as perception and movement, from which intelligence develops. Yet biology alone cannot explain why two plus two equals four, or why certain logical conclusions appear necessary to the human mind.

This leads to a second approach: the view that logical and mathematical relations cannot be reduced to biological processes and that the higher functions of intelligence must therefore be understood through logic itself.

But logic cannot simply replace psychology. Formal logic describes the structures of thought when they have reached a state of equilibrium; psychology, by contrast, seeks to understand how those structures develop.

The psychology of intelligence must therefore take logical discoveries into account, but logic cannot dictate psychological explanations. It can identify problems and structures, while psychology must investigate how these structures arise and develop.

We must begin, then, with the dual nature of intelligence: it is both biological and logical. The task is to understand how these two apparently different aspects of human thought can be brought together within a unified explanation.

### THE PLACE OF INTELLIGENCE IN MENTAL ORGANIZATION

Every response — whether an outward action or an internal act of thought — represents a form of adaptation, or more precisely, re-adaptation.

An individual acts when a need arises, that is, when the balance between the organism and its environment has been disturbed. Action tends to restore that balance and to establish a new adaptation between the individual and the surrounding world.

A response is therefore a form of interaction between the subject and the external environment. Unlike purely physiological interactions, however, the responses studied by psychology are functional rather than simply material. They can operate across increasing distances in space, as in perception, and across increasing distances in time, as in memory. They may also follow increasingly complex paths, involving reversals, indirect routes and combinations of actions.

Behaviour understood in this way contains two fundamental and closely connected dimensions: an affective dimension and a cognitive dimension.

The relationship between emotion and cognition has long been debated. Some psychologists have distinguished between action directed toward an object and the individual's emotional response to his or her own actions. From this perspective, feelings regulate the energy of behaviour.

Others have argued that feelings determine the goals of behaviour while intelligence provides the means for reaching them. Yet human beings are conscious not only of the means they use but also of their goals, and this awareness continually modifies the direction of their actions.

It may therefore be more accurate to say that emotion provides the energy required for action, while cognition gives that action its structure.

Gestalt psychology approached the problem in a similar way by viewing behaviour as part of a total field that includes both the individual and the objects of experience. The dynamics of this field are connected with feeling, while its organization depends upon perception, action and intelligence.

We can accept a similar formulation, provided that we recognize that neither emotions nor cognitive structures depend only on the immediate situation. They are also shaped by the individual's entire previous history.

Every action therefore has both an affective or energetic aspect and a cognitive or structural aspect. These two dimensions cannot be separated in actual behaviour.

[...]

Sensorimotor intelligence eventually produces an empirical organization of bodily movements. These movements can involve reversals, detours and coordinated actions directed toward practical goals.

At this early stage, however, we cannot yet speak of a true system of mental operations. The organization exists primarily in actions that are actually performed. Spatial, temporal, logical, numerical and practical relations are still closely intertwined and have not yet become differentiated into independent systems of thought.

With the emergence of symbolic representation, an important change takes place. Practical action begins to separate from mental representation. The child can now represent objects and events that are not immediately present.

At first, however, logical and numerical operations are still closely connected with spatial and temporal experience. Thought remains largely intuitive and pre-operational.

Around the age of seven or eight, a new form of organization appears. Logical and numerical operations become increasingly independent from immediate perception and action. Children become capable of understanding classes, relationships, number and reversible operations in a more systematic way.

Later, with the development of formal operations, thought becomes capable of moving beyond concrete situations. The individual can reason about hypotheses, possibilities and propositions without depending entirely on direct experience.

This marks an important transformation: intelligence is no longer limited to organizing actions performed in the real world but can operate upon possible situations and abstract relationships.

[...]

A response, then, is a particular form of interaction between the individual and the external world. Unlike physiological interactions, which involve material changes within the organism, psychological responses are functional. They can extend across space through perception and across time through memory, while becoming increasingly complex through indirect actions, reversals and alternative paths.