The paper deals with several problems concerning with notion of truth. The author is interested in logical aspects of the definition of truth given by Ajdukiewicz and Kotarbinski. He introduces the multimodal logical calculus with propositional quantifier and applies it to analysis of some formulations of the definition. The analysis is focused on two main formulations of the definition, namely on absolute and partial formulation. It is shown that the notion of truth specified by absolute formulation is unconstructive i.e. it is possible to state that some utterance is true without stating any sentence which express the propositional content of the utterance. On the other hand after the partial formulation the notion of truth seems to have some counterintuitive features, for example the falsehood is no longer the same as the lack of truth. Moreover only the absolute approach leads to difficulties connected with the Liar Paradox.
Financed by the National Centre for Research and Development under grant No. SP/I/1/77065/10 by the strategic scientific research and experimental development program:
SYNAT - “Interdisciplinary System for Interactive Scientific and Scientific-Technical Information”.