Assertion, denial and non-classical theories

Greg Restall*

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingChapter

36 Citations (Scopus)


In this paper I urge friends of truth-value gaps and truth-value gluts-proponents of paracomplete and paraconsistent logics-to consider theories not merely as sets of sentences, but as pairs of sets of sentences, or what I call ‘bitheories,’ which keep track not only of what holds according to the theory, but also what fails to hold according to the theory. I explain the connection between bitheories, sequents, and the speech acts of assertion and denial. I illustrate the usefulness of bitheories by showing how they make available a technique for characterising different theories while abstracting away from logical vocabulary such as connectives or quantifiers, thereby making theoretical commitments independent of the choice of this or that particular non-classical logic. Examples discussed include theories of numbers, classes and truth. In the latter two cases, the bitheoretical perspective brings to light some heretofore unconsidered puzzles for friends of naïve theories of classes and truth.

Original languageEnglish
Title of host publicationParaconsistency
Subtitle of host publicationLogic and Applications
Number of pages19
ISBN (Electronic)9789400744387
ISBN (Print)9789400744370
Publication statusPublished - 1 Jan 2013


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