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. (Jean Piaget)
In other words, knowledge of the external world begins with an immediate utilisation of things, whereas knowledge of self is stopped by this purely practical and utilitarian contact. (Jean Piaget)
This means that no single logic is strong enough to support the total construction of human knowledge. (Jean Piaget)
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. (Jean Piaget)
To express the same idea in still another way, I think that human knowledge is essentially active. (Jean Piaget)
It is with children that we have the best chance of studying the development of logical knowledge, mathematical knowledge, physical knowledge, and so forth. (Jean Piaget)
Knowledge, then, is a system of transformations that become progressively adequate. (Jean Piaget)
Scientific knowledge is in perpetual evolution; it finds itself changed from one day to the next. (Jean Piaget)