Abstract

S. Jaśkowski introduced the discussive propositional calculus D₂ as a basis for a logic which could be used as underlying logic of inconsistent but nontrivial theories. D₂ has afterwards been extended to a first-order predicate calculus and to a higher-order logic. In this paper we present a natural version of D₂, in the sense of Jaśkowski and Gentzen; as a consequence, we suggest a new formulation of the discussive predicate calculus. A semantics for the new calculus is also presented.