 Clearly there is a difference between Kolmogorov’s own explanation and Heyting’s explanation in Kolmogorov’s terms. Where Heyting says that a proof of \(\neg a\) establishes a reduction of the solution of any problem to that of \(a\), Kolmogorov had said that it established that the problem of reducing the solution of any problem to that of \(a\) has become without content. One has the impression that Heyting in his explanation of Ex Falso tries to approximate as closely as possible the explanation for ordinary implications in terms of a concrete constructive connection between antecedent and consequent; this is even clearer in the explanation he would give of Ex Falso in 1956 (see  section 5.4  below). (Note that neither Heyting nor Kolmogorov ever justified Ex Falso by giving the traditional argument (based on the disjunctive syllogism) also stated in Glivenko’s paper from 1929; see  section 4.3  above.)