A Classical Logic of Nonsense

SZMUC, DAMIÁN ENRIQUE

Bristol

Seminario; FSB Seminar; 2020

University of Bristol

Logics of nonsense are systems that allow sentences to be meaningless and that dictate how to reason in their presence. This alternative is formally represented by the inclusion of a third truth-value, besides truth and falsity, which acts infectiously: a compound formula is meaningless whenever one of its components is. Given the usual definition of validity in terms of preservation of designated values, logics of nonsense typically invalidate some inference that is classically valid. Whether they include the meaningless value among the designated or not, respectively, they invalidate Conjunction Elimination or Disjunction Introduction. The aim of this paper is to present a logic of nonsense that overcomes this difficulty, i.e. that validates exactly the same inferences than Classical Logic. This is achieved thanks to defining validity in terms of ST-consequence, as presented by Cobreros, Egré, Ripley and van Rooij. In doing so, the paper also discusses some philosophical consequences of this approach.