Add to ORKGThere are cases where we mix two or more exact concepts in one intuitive concept and then we seem to arrive at paradoxical results. Hao Wang. During the last decade both mathematicians and philosophers have been interested in the development of various theories of constructions. The study of these theories has been prompted by at least three sorts of con-siderations. The first theories were proposed by Kreisel around 1960 as a means of formalizing the intended interpreation for the intuitionistic logical constants as presented in Heyting’s Introduction from 1956. Here, in Kreisel’s version, the relation construction c proves proposition A was given a step-wise analysis according to the complexity of A, in much the same way as the truth-tabl...