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.

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

To understand is to invent.

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.

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

How much more precious is a little humanity than all the rules in the world.

What is desired is that the teacher ceased being a lecturer, satisfied with transmitting ready-made solutions. His role should rather be that of a mentor stimulating initiative and research.