Paraconsistency, paracompleteness, and valuation

Authors

Newton C. A. da Costa
University of São Paulo image/svg+xml

Synopsis

This paper presents a propositional system that is simultaneously paracon-sistent and paracomplete, offering a semantic framework grounded in valuation the-ory. The authors define paraconsistency as the ability of a logic to tolerate contradic-tions without collapsing into triviality, and paracompleteness as the failure to satisfy thelaw of the excluded middle. The work introduces a logical system,𝜋, with weak prim-itive negation and a definable classical negation. Through valuation semantics and themethod of valuation-tableaux, the authors demonstrate the decidability of𝜋, while alsoproving that𝜋is not characterizable by any finite-valued matrix.

Author Biographies

Andrea M. Loparić, University of São Paulo

Professora Sênior pela Universidade de São Paulo (USP).

Newton C. A. da Costa, University of São Paulo

Professor Sênior na Universidade de São Paulo (USP). 

Downloads

Published

August 21, 2025