Jean Piaget

Childish egocentrism is, in its essence, an inability to differentiate between the ego and the social environment.

Logical reasoning is an argument which we have with ourselves and which reproduces internally the features of a real argument.

Knowing reality means constructing systems of transformations that correspond, more or less adequately, to reality.

Scientific knowledge is in perpetual evolution; it finds itself changed from one day to the next.

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.

It is with children that we have the best chance of studying the development of logical knowledge, mathematical knowledge, physical knowledge, and so forth.

Reflective abstraction, however, is based not on individual actions but on coordinated actions.

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 more the schemata are differentiated, the smaller the gap between the new and the familiar becomes, so that novelty, instead of constituting an annoyance avoided by the subject, becomes a problem and invites searching.

The self thus becomes aware of itself, at least in its practical action, and discovers itself as a cause among other causes and as an object subject to the same laws as other objects.

Scientific thought, then, is not momentary; it is not a static instance; it is a process.

To reason logically is so to link one's propositions that each should contain the reason for the one succeeding it, and should itself be demonstrated by the one preceding it. Or at any rate, whatever the order adopted in the construction of one's own exposition, it is to demonstrate judgments by each other.

To express the same idea in still another way, I think that human knowledge is essentially active.

Play is the work of childhood.

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.

The goal of education is not to increase the amount of knowledge but to create the possibilities for a child to invent and discover, to create men who are capable of doing new things.

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.

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.

This means that no single logic is strong enough to support the total construction of human knowledge.

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.

I have always detested any departure from reality, an attitude which I relate to my mother's poor mental health.