Chance... in the accommodation peculiar to sensorimotor intelligence, plays the same role as in scientific discovery. It is only useful to the genius and its revelations remain meaningless to the unskilled.

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.

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

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.

It was while teaching philosophy that I saw how easily one can say ... what one wants to say. ... In fact, I became particularly aware if the dangers of speculation ... It's so much easier than digging out the facts. You sit in your office and build a system. But with my training in biology, I felt this kind of undertaking precarious.

Intelligence is what you use when you don't know what to do.

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