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.
The article presents the most important stages of research on the metaphysics of situations contained in Wittgenstein’s Tractatus carried by Professor Bogusław Wolniewicz.