O krytyce determinizmu i logice wielowartościowej Jana Łukasiewicza

Abstract

The article focuses on Jan Łukasiewicz’s thesis that the truth or falsity of some propositions about the future – future contingents – entails determinism. According to Łukasiewicz, determinism could be avoided by rejecting the classical logic (two-valued logic) and replacing it with many-valued logic (three-valued logic). Łukasiewicz’s position is taken under the examination from the point of view of Susan Haack’s thesis. In her opinion, the truth values of future contingents do not entail any determinism. I argue in the paper that Haack’s view is incorrect because it does not take into account all the premises accepted by Łukasiewicz. The most important of them concern the semantics of future verbs. Łukasiewicz, as I try to show, assumes the so called Peircean semantics and not the Ockhamist one. Next, I try to argue that it is possible to preserve the validity of Łukasiewicz’s reasoning, which led him to the three-valued logic by taking into account his assumptions regarding the meaning of future verbs.