Revisiting the Dunn-Belnap logic

Abstract

In the present work I introduce a semantics based on the cognitive attitudes of acception and rejection entertainedby a given society of agents for logics inspired onDunn andBelnap’s FirstDegreeEntailment (E). In contrast to the epistemic situations originally employed by E, the cognitive attitudes do not coincide with truth-values and they seemmore suitable to logics that intend to consider the informational content of propositions “said to be true” as well as of propositions “said to be false” as determinant of the notion of logical validity. After analyzing some logics associated to the proposed semantics, we introduce the logic E , whose underlying entailment relation—theB-entailment—is able to express several kinds of reasoning involving the cognitive attitudes of acceptance and rejection. A sound and complete sequent calculus for E is also presented.