Jean Piaget

Intelligence is what you use when you don't know what to do: when neither innateness nor learning has prepared you for the particular situation.

The main functions of intelligence, that of inventing solutions and that of verifying them, do not necessarily involve one another. The first partakes of imagination; the second alone is properly logical.

Logical activity is not the whole of intelligence. One can be intelligent without being particularly logical.

The current state of knowledge is a moment in history, changing just as rapidly as the state of knowledge in the past has ever changed and, in many instances, more rapidly.

The principle goal of education in the schools should be creating men and women who are capable of doing new things, not simply repeating what other generations have done.

I engage my subjects in conversation, patterned after psychiatric questioning, with the aim of discovering something about the reasoning underlying their right but especially their wrong answers.

From this time on, the universe is built up into an aggregate of permanent objects connected by causal relations that are independent of the subject and are placed in objective space and time.

The child of three or four is saturated with adult rules. His universe is dominated by the idea that things are as they ought to be, that everyone's actions conform to laws that are both physical and moral - in a word, that there is a Universal Order.

To accustom the infant to get out of its own difficulties or to calm it by rocking it may be to lay the foundations of a good or of a bad disposition.

Our problem, from the point of view of psychology and from the point of view of genetic epistemology, is to explain how the transition is made from a lower level of knowledge to a level that is judged to be higher.

In genetic epistemology, as in developmental psychology, too, there is never an absolute beginning.

Logical positivists have never taken psychology into account in their epistemology, but they affirm that logical beings and mathematical beings are nothing but linguistic structures.