Lógica, informação e evidência: sobre a abordagem epistêmica da paraconsistência

Abstract

Logical consequence in Classical Logic is traditionally interpreted as truth preservation. Following the emergence of alternative logics – particularly paraconsistent and paracomplete logics, which reject, respectively, the principle of explosion and the principle of excluded middle – the debate on how to interpret the consequence relation in such systems gains relevance in philosophy of logic. According to Graham Priest’s dialetheism, paraconsistency is necessary to adequately model natural reasoning, given the existence of true contradictions. However, the preference for paraconsistent and paracomplete systems may be motivated by different reasons, not necessarily related to a specific perspective on the notion of truth. One can interpret logical consequence, for instance, as preservation of availability of information, as in Belnap-Dunn’s four-valued logic. The epistemic approach to paraconsistency, developed by Carnielli and Rodrigues, is a proposal for interpreting certain paraconsistent and paracomplete systems in terms of preservation of availability of evidence, according to which contradictions are understood as conflicting evidence and excluded middle violations are understood as lack of evidence concerning a given proposition. Furthermore, this approach distinguishes between non-conclusive evidence, which allows for paraconsistent and paracomplete cases, and conclusive evidence, for which the classical treatment should be recovered. This approach was developed alongside a family of formal systems called Logics of Evidence and Truth, which incorporate a classicality operator into their vocabulary, enabling the recovery of classical treatment for specific propositions. These systems, interpreted as intended, are not in conflict with Classical Logic, as they align with logical pluralism – according to which there is no single correct logical system – as opposed to logical monism, defended, for instance, by Graham Priest. This study aims to present the epistemic approach to paraconsistency and paracompleteness, as well as to analyze and discuss some criticisms directed at it, emphasizing issues related to the notions of evidence and information, as well as the opposition between the epistemic approach and Priest’s dialetheism.