
384On Artifacts and TruthPreservationAustralasian Journal of Logic 12 (3): 135158. 2015.In Saving Truth from Paradox, Hartry Field presents and defends a theory of truth with a new conditional. In this paper, I present two criticisms of this theory, one concerning its assessments of validity and one concerning its treatment of truthpreservation claims. One way of adjusting the theory adequately responds to the truthpreservation criticism, at the cost of making the validity criticism worse. I show that in a restricted setting, Field has a way to respond to the validity criticism. …Read more

370Contraction and revisionAustralasian Journal of Logic 13 (3): 5877. 2016.An important question for proponents of noncontractive approaches to paradox is why contraction fails. Zardini offers an answer, namely that paradoxical sentences exhibit a kind of instability. I elaborate this idea using revision theory, and I argue that while instability does motivate failures of contraction, it equally motivates failure of many principles that noncontractive theorists want to maintain.

340Conditionals in Theories of TruthJournal of Philosophical Logic 46 (1): 2763. 2017.We argue that distinct conditionals—conditionals that are governed by different logics—are needed to formalize the rules of Truth Introduction and Truth Elimination. We show that revision theory, when enriched with the new conditionals, yields an attractive theory of truth. We go on to compare this theory with one recently proposed by Hartry Field.

229The Relevant Logic E and Some Close Neighbours: A ReinterpretationIfCoLog Journal of Logics and Their Applications 4 (3): 695730. 2017.This paper has two aims. First, it sets out an interpretation of the relevant logic E of relevant entailment based on the theory of situated inference. Second, it uses this interpretation, together with Anderson and Belnap’s natural deduc tion system for E, to generalise E to a range of other systems of strict relevant implication. Routley–Meyer ternary relation semantics for these systems are produced and completeness theorems are proven.

226The Tarskian Turn: Deflationism and Axiomatic TruthPhilosophical Review 122 (1): 144147. 2013.

53Intersubstitutivity principles and the generalization function of truthSynthese 195 (3): 10651075. 2018.We offer a defense of one aspect of Paul Horwich’s response to the Liar paradox—more specifically, of his move to preserve classical logic. Horwich’s response requires that the full intersubstitutivity of ‘ ‘A’ is true’ and A be abandoned. It is thus open to the objection, due to Hartry Field, that it undermines the generalization function of truth. We defend Horwich’s move by isolating the grade of intersubstitutivity required by the generalization function and by providing a new reading of the…Read more

53Review of Stewart Shapiro's Varieties of Logic (review)Notre Dame Philosophical Reviews 2015. 2015.

44Solovaytype theorems for circular definitionsReview of Symbolic Logic 8 (3): 467487. 2015.We present an extension of the basic revision theory of circular definitions with a unary operator, □. We present a Fitchstyle proof system that is sound and complete with respect to the extended semantics. The logic of the box gives rise to a simple modal logic, and we relate provability in the extended proof system to this modal logic via a completeness theorem, using interpretations over circular definitions, analogous to Solovay’s completeness theorem forGLusing arithmetical interpretations…Read more

35Translations Between Gentzen–Prawitz and Jaśkowski–Fitch Natural Deduction ProofsStudia Logica 107 (6): 11031134. 2019.Two common forms of natural deduction proof systems are found in the Gentzen–Prawitz and Jaśkowski–Fitch systems. In this paper, I provide translations between proofs in these systems, pointing out the ways in which the translations highlight the structural rules implicit in the systems. These translations work for classical, intuitionistic, and minimal logic. I then provide translations for classical S4 proofs.

33Actual Issues for Relevant LogicsErgo: An Open Access Journal of Philosophy 7. 2020.In this paper, I motivate the addition of an actuality operator to relevant logics. Straightforward ways of doing this are in tension with standard motivations for relevant logics, but I show how to add the operator in a way that permits one to maintain the intuitions behind relevant logics. I close by exploring some of the philosophical consequences of the addition.

30Proof Theory for Functional Modal LogicStudia Logica 106 (1): 4984. 2018.We present some prooftheoretic results for the normal modal logic whose characteristic axiom is \. We present a sequent system for this logic and a hypersequent system for its firstorder form and show that these are equivalent to Hilbertstyle axiomatizations. We show that the question of validity for these logics reduces to that of classical tautologyhood and firstorder logical truth, respectively. We close by proving equivalences with a Fitchstyle proof system for revision theory.

20NonClassical Circular DefinitionsAustralasian Journal of Logic 14 (1). 2017.Circular denitions have primarily been studied in revision theory in the classical scheme. I present systems of circular denitions in the Strong Kleene and supervaluation schemes and provide complete proof systems for them. One class of denitions, the intrinsic denitions, naturally arises in both schemes. I survey some of the features of this class of denitions.

14Tracking reasons with extensions of relevant logicsLogic Journal of the IGPL 27 (4): 543569. 2019.In relevant logics, necessary truths need not imply each other. In justification logic, necessary truths need not all be justified by the same reason. There is an affinity to these two approaches that suggests their pairing will provide good logics for tracking reasons in a finegrained way. In this paper, I will show how to extend relevant logics with some of the basic operators of justification logic in order to track justifications or reasons. I will define and study three kinds of frames for…Read more

5Translations between linear and tree natural deduction systems for relevant logicsReview of Symbolic Logic 122. forthcoming.Anderson and Belnap presented indexed Fitchstyle natural deduction systems for the relevant logics R, E, and T. This work was extended by Brady to cover a range of relevant logics. In this paper I present indexed tree natural deduction systems for the Anderson–Belnap–Brady systems and show how to translate proofs in one format into proofs in the other, which establishes the adequacy of the tree systems.

4Identity in MaresGoldblatt Models for Quantified Relevant LogicJournal of Philosophical Logic 127. forthcoming.Mares and Goldblatt, 163–187, 2006) provided an alternative frame semantics for two quantified extensions of the relevant logic R. In this paper, I show how to extend the MaresGoldblatt frames to accommodate identity. Simpler frames are provided for two zeroorder logics en route to the full logic in order to clarify what is needed for identity and substitution, as opposed to quantification. I close with a comparison of this work with the FineMares models for relevant logics with identity and …Read more
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Revision Theory of Truth 
Proof Theory 