Contradictions without negation and a proof-theoretic, bilateralist account of connexive logics
In this talk I will investigate a negation-free fragment of a connexive logic from the perspective of bilateralist proof-theoretic semantics and will argue that eliminating primitive negation has two important conceptual consequences. First, it requires a reconceptualization of contradictory logics: in a bilateralist framework, contradiction need not be understood in terms of negation inconsistency, but rather as the coexistence of proofs and refutations for certain formulas within a non-trivial system. Second, it challenges the standard definition of connexive logics, which typically rely on negation-based schemata. Finally, I will also address the issue of proof/refutation duality in the absence of negation, which can be formalized and recovered at a meta-level by extending the system with a two-sorted typed lambda-calculus.
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On Wyman’s Theory of the Meaninglessness of Contradictions: Cancellation View of Negation and Reductio ad Absurdum
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Cooper's Logic of Ordinary Discourse
Coherence and Connexivity
Solving a New Paradox of Deontic Logic (and a dozen other paradoxes) with RNmatrices for MC-based Modal Logics
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Remarks on strong dimathematism
In a sort of hostile review of Graham Priest's monograph Beyond the Limits of Thought, Cambridge University Press, 1995, that appeared in Review of Modern Logic, 1996, 437-439, Maria Frapolli comments on Priest's dialetheism, the view that there exist true contradictions, as follows:
"Contradictions are marks of error, not announcements of a deeper truth. Priest defends his position as if it were the battle of tolerance versus scholastic dogmatism. But, as I see it, we do not stand here in front of a dispute between antiquated orthodoxy and liberalizing heterodoxy, but between philosophy and charlatanism."
Thirty years after the publication of Beyond the Limits of Thought, dialetheism is widely regarded as a coherent and completely respectable view. Nevertheless, even if contradictions are not necessarily seen as marks of error, it may be irritating to consider it as theoretically rational to deal with non-trivial logics that are not only contradiction-tolerant in the sense of being paraconsistent but contain provable contradictions. In my talk, I will elaborate on a view that I have called "strong dimathematism" and that is meant as a contribution to making sense of provable contradictions in non-trivial negation inconsistent logics.
Constructiveness and connexivity
According to some authors, intuitionistic logic is the correct constructive logic. Sara Negri and Jan von Plato (Structural Proof Theory, Cambridge University Press, 2001, p. 25), for example, write that "[i]ntuitionistic reasoning and constructive reasoning ... are the same thing." In this talk, I will discuss the constructiveness of the non-trivial negation inconsistent hyperconnexive logic C, that is a conservative extension of positive intuitionistic logic. I will end with some comments on Leibniz-identity in second-order C.
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