«The correspoindence between Beth and Piaget, edited and annotated by Gerhard Heinzmann, Alain Trognon and Frederik Tremblay, was kindly made available to us by The Beth Foundation in Amsterdam. It constitutes a very exceptional document (...). It is, in fact a dialogue, more precisely an epistolary dialogue, but at the same time it has all the properties of a critical discussion conducted within the framework of an interdisciplinary scientific project. It focuses on the relationship between "natural mind" and "formal thinking", a long-standing issue in epistemology and one of the main points discusses by the members of Lorenzen's Erlangen School.»
«The two men end the systematic quarrel that shapes their corresondence by finding, in the joint 1961 volume, a meager compromise. Their activities as logician and psychologist refers to one another, not because they are interdependent, but because they are complementary (Beth and Piaget 1961, p. 332)»
A very disappointing conclusion. But may such a question be closed forever? Who can say that?