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.

Logic and mathematics are nothing but specialised linguistic structures.

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

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

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.

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