EN
We owe the terms ‘diachronic logic’ and ‘non-Fregean logic’ to Roman Suszko. Suszko called ‘diachronic logic’ application of classical logic to study the development of knowledge. But non-Fregean logic is logical calculus obtained from the classical logic by adding identity connective and axioms for it. The main goal of the paper is to prove that the non-Fregean logic is certain continuation of diachronic logic.