Jerzy Łoś’s Epistemic Logic and the Origins of Epistemic Logics

Abstrakt

The paper presents Jerzy Łoś’s system of epistemic logic, which is
the world’s first system of epistemic logic. We characterise this system and give an
analysis of its theses in the light of the theory of rational behaviour. We notice that
some theses are adequate to the characterization of the rational belief, but some
of them are too much idealization of rational behaviour. Next, we check Nicolaus
Rescher’s systems of assertion and relation between them and Łoś’s system. We also
analyse so-called Carthesian system constructed by Witold Marciszewski, which is
intended as improvement of Łoś’s system.