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  1.  20
    Grzegorczyk and Whitehead Points: The Story Continues.Rafał Gruszczyński & Santiago Jockwich Martinez - 2024 - Journal of Philosophical Logic 53 (3):695-719.
    The paper is devoted to the analysis of two seminal definitions of points within the region-based framework: one by Whitehead (1929) and the other by Grzegorczyk (Synthese, 12(2-3), 228-235 1960). Relying on the work of Biacino & Gerla (Notre Dame Journal of Formal Logic, 37(3), 431-439 1996), we improve their results, solve some open problems concerning the mutual relationship between Whitehead and Grzegorczyk points, and put forward open problems for future investigation.
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  2.  20
    Exact Truthmaker Semantics for Modal Logics.Dongwoo Kim - 2024 - Journal of Philosophical Logic 53 (3):789-829.
    The present paper attempts to provide an exact truthmaker semantical analysis of modalized propositions. According to the present proposal, an exact truthmaker for “Necessarily _P_” is a state that bans every exact truthmaker for “Not _P_”, and an exact truthmaker for “Possibly _P_” is a state that allows an exact truthmaker for _P_. Based on this proposal, a formal semantics will be developed; and the soundness and completeness results for a well-known family of the systems of normal modal propositional logic (...)
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  3.  43
    Jeffrey Conditionalization Permits Undermining.Marc Lange - 2024 - Journal of Philosophical Logic 53 (3):585-591.
    It has frequently been argued recently that Jeffrey Conditionalization (JC) does not permit undermining. For JC to be inapplicable in cases where the evidence could be undermined would severely compromise JC’s range. However, this paper contends that the argument fails to show that JC cannot accommodate undermining. This response turns on using the proper partition to capture the direct impact of our evidence in redistributing our credences.
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  4.  26
    Counterpart Theory and Actuality.James Milford - 2024 - Journal of Philosophical Logic 53 (3):679-694.
    Lewis (The Journal of Philosophy, 65(5), 113–126, 1968) attempts to provide an account of modal talk in terms of the resources of counterpart theory, a first-order theory that eschews transworld identity. First, a regimentation of natural language modal claims into sentences of a formal first-order modal language L is assumed. Second, a translation scheme from L-sentences to sentences of the language of the theory is provided. According to Hazen (The Journal of Philosophy, 76(6), 319–338, 1979) and Fara & Williamson (Mind, (...)
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  5.  8
    On Some Weakened Forms of Transitivity in the Logic of Conditional Obligation.Xavier Parent - 2024 - Journal of Philosophical Logic 53 (3):721-760.
    This paper examines the logic of conditional obligation, which originates from the works of Hansson, Lewis, and others. Some weakened forms of transitivity of the betterness relation are studied. These are quasi-transitivity, Suzumura consistency, acyclicity and the interval order condition. The first three do not change the logic. The axiomatic system is the same whether or not they are introduced. This holds true under a rule of interpretation in terms of maximality and strong maximality. The interval order condition gives rise (...)
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  6.  11
    Common Ground in Non-face-to-face Communication: In Sensu Diviso or In Sensu Composito.Merel Semeijn - 2024 - Journal of Philosophical Logic 53 (3):657-678.
    Traditional definitions of common ground in terms of iterative de re attitudes do not apply to conversations where at least one conversational participant is not acquainted with the other(s). I propose and compare two potential refinements of traditional definitions based on Abelard’s distinction between generality in sensu composito and in sensu diviso.
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  7.  13
    Questions & Indexicality.Thom van Gessel - 2024 - Journal of Philosophical Logic 53 (3):593-621.
    The truth conditions of sentences with indexicals like ‘I’ and ‘here’ cannot be given directly, but only relative to a context of utterance. Something similar applies to questions: depending on the semantic framework, they are given truth conditions relative to an actual world, or support conditions instead of truth conditions. Two-dimensional semantics can capture the meaning of indexicals and shed light on notions like apriority, necessity and context-sensitivity. However, its scope is limited to statements, while indexicals also occur in questions. (...)
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  8.  12
    A Hyperintensional Logic of Non-prime Evidence.Pietro Vigiani - 2024 - Journal of Philosophical Logic 53 (3):761-788.
    We present a logic of evidence that reduces agents’ epistemic idealisations by combining classical propositional logic with substructural modal logic for formulas in the scope of epistemic modalities. To this aim, we provide a neighborhood semantics of evidence, which provides a modal extension of Fine’s semantics for relevant propositional logic. Possible worlds semantics for classical propositional logic is then obtained by defining the set of possible worlds as a special subset of information states in Fine’s semantics. Finally, we prove that (...)
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  9.  13
    First-Degree Entailment and Truthmaker Functions.Roderick Batchelor - 2024 - Journal of Philosophical Logic 53 (2):373-390.
    We define a concept of truthmaker function, and prove the functional completeness, w.r.t. truthmaker functions in this sense, of a set of four-valued functions corresponding to standard connectives of the system of relevance logic known as First-Degree Entailment or Belnap–Dunn logic.
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  10. A Semantic Framework for the Impure Logic of Ground.Louis deRosset - 2024 - Journal of Philosophical Logic 53 (2):463-491.
    There is a curious bifurcation in the literature on ground and its logic. On the one hand, there has been a great deal of work that presumes that logical complexity invariably yields grounding. So, for instance, it is widely presumed that any fact stated by a true conjunction is grounded in those stated by its conjuncts, that any fact stated by a true disjunction is grounded in that stated by any of its true disjuncts, and that any fact stated by (...)
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  11.  28
    A Dynamic Logic of Data-Informed Knowledge.Kaya Deuser, Junli Jiang, Pavel Naumov & Wenxuan Zhang - 2024 - Journal of Philosophical Logic 53 (2):521-557.
    With agents relying more and more on information from central servers rather than their own sensors, knowledge becomes property not of a specific agent but of the data that the agents can access. The article proposes a dynamic logic of data-informed knowledge that describes an interplay between three modalities and one relation capturing the properties of this form of knowledge. The main technical results are the undefinability of two dynamic operators through each other, a sound and complete axiomatisation, and a (...)
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  12.  20
    Ab Esse ad Posse Non Valet Consequentia.Daniel Dohrn - 2024 - Journal of Philosophical Logic 53 (2):391-409.
    While knowledge of mere possibilities is difficult to understand, knowledge of possibilities that are actual seems unproblematic (as far as we know the actual world). The principle that what is actual is possible has been near-universally accepted. After summarizing some sporadic dissent, I present a proposal for how the validity of the principle might be restricted. While the principle certainly holds for sufficiently inclusive objective and epistemic possibilities, it may not hold when the accessibility of possibilities is contextually restricted.
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  13. Naïve Truth and the Evidential Conditional.Andrea Iacona & Lorenzo Rossi - 2024 - Journal of Philosophical Logic 53 (2):559-584.
    This paper develops the idea that valid arguments are equivalent to true conditionals by combining Kripke’s theory of truth with the evidential account of conditionals offered by Crupi and Iacona. As will be shown, in a first-order language that contains a naïve truth predicate and a suitable conditional, one can define a validity predicate in accordance with the thesis that the inference from a conjunction of premises to a conclusion is valid when the corresponding conditional is true. The validity predicate (...)
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  14.  23
    Truthlikeness and the Number of Planets.Theo A. F. Kuipers - 2024 - Journal of Philosophical Logic 53 (2):493-520.
    Examples of hypotheses about the number of planets are frequently used to introduce the topic of (actual) truthlikeness but never analyzed in detail. In this paper we first deal with the truthlikeness of singular quantity hypotheses, with reference to several ‘the number of planets’ examples, such as ‘The number of planets is 10 _versus_ 10 billion (instead of 8).’ For the relevant ratio scale of quantities we will propose two, strongly related, normalized metrics, the proportional metric and the (simplest and (...)
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  15.  9
    8 Valued Non-Deterministic Semantics for Modal Logics.Pawel Pawlowski & Daniel Skurt - 2024 - Journal of Philosophical Logic 53 (2):351-371.
    The aim of this paper is to study a particular family of non-deterministic semantics for modal logics that has eight truth-values. These eight-valued semantics can be traced back to Omori and Skurt (2016), where a particular member of this family was used to characterize the normal modal logic K. The truth-values in these semantics convey information about a proposition’s truth/falsity, whether the proposition is necessary/not necessary, and whether it is possible/not possible. Each of these triples is represented by a unique (...)
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  16. Supervaluationism, Modal Logic, and Weakly Classical Logic.Joshua Schechter - 2024 - Journal of Philosophical Logic 53 (2):411-61.
    A consequence relation is strongly classical if it has all the theorems and entailments of classical logic as well as the usual meta-rules (such as Conditional Proof). A consequence relation is weakly classical if it has all the theorems and entailments of classical logic but lacks the usual meta-rules. The most familiar example of a weakly classical consequence relation comes from a simple supervaluational approach to modelling vague language. This approach is formally equivalent to an account of logical consequence according (...)
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  17.  10
    An Algebraic View of the Mares-Goldblatt Semantics.Andrew Tedder - 2024 - Journal of Philosophical Logic 53 (2):331-349.
    An algebraic characterisation is given of the Mares-Goldblatt semantics for quantified extensions of relevant and modal logics. Some features of this more general semantic framework are investigated, and the relations to some recent work in algebraic semantics for quantified extensions of non-classical logics are considered.
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  18.  91
    Mathematical Modality: An Investigation in Higher-order Logic.Andrew Bacon - 2024 - Journal of Philosophical Logic 53 (1):131-179.
    An increasing amount of contemporary philosophy of mathematics posits, and theorizes in terms of special kinds of mathematical modality. The goal of this paper is to bring recent work on higher-order metaphysics to bear on the investigation of these modalities. The main focus of the paper will be views that posit mathematical contingency or indeterminacy about statements that concern the ‘width’ of the set theoretic universe, such as Cantor’s continuum hypothesis. Within a higher-order framework I show that contingency about the (...)
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  19.  29
    A Sound and Complete Tableaux Calculus for Reichenbach’s Quantum Mechanics Logic.Pablo Caballero & Pablo Valencia - 2024 - Journal of Philosophical Logic 53 (1):223-245.
    In 1944 Hans Reichenbach developed a three-valued propositional logic (RQML) in order to account for certain causal anomalies in quantum mechanics. In this logic, the truth-value _indeterminate_ is assigned to those statements describing physical phenomena that cannot be understood in causal terms. However, Reichenbach did not develop a deductive calculus for this logic. The aim of this paper is to develop such a calculus by means of First Degree Entailment logic (FDE) and to prove it sound and complete with respect (...)
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  20.  24
    Reasoning about Dependence, Preference and Coalitional Power.Qian Chen, Chenwei Shi & Yiyan Wang - 2024 - Journal of Philosophical Logic 53 (1):99-130.
    This paper presents a logic of preference and functional dependence (LPFD) and its hybrid extension (HLPFD), both of whose sound and strongly complete axiomatization are provided. The decidability of LPFD is also proved. The application of LPFD and HLPFD to modelling cooperative games in strategic form is explored. The resulted framework provides a unified view on Nash equilibrium, Pareto optimality and the core. The philosophical relevance of these game-theoretical notions to discussions of collective agency is made explicit. Some key connections (...)
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  21.  27
    A Step Towards Absolute Versions of Metamathematical Results.Balthasar Grabmayr - 2024 - Journal of Philosophical Logic 53 (1):247-291.
    There is a well-known gap between metamathematical theorems and their philosophical interpretations. Take Tarski’s Theorem. According to its prevalent interpretation, the collection of all arithmetical truths is not arithmetically definable. However, the underlying metamathematical theorem merely establishes the arithmetical undefinability of a set of specific Gödel codes of certain artefactual entities, such as infix strings, which are true in the standard model. That is, as opposed to its philosophical reading, the metamathematical theorem is formulated (and proved) relative to a specific (...)
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  22.  22
    Tarski’s Theory of the Formal Correctness of Definitions.David Hitchcock - 2024 - Journal of Philosophical Logic 53 (1):181-221.
    In his 1933 monograph on the concept of truth, Alfred Tarski claimed that his definition of truth satisfied “the usual conditions of methodological correctness”, which in a 1935 article he identified as consistency and back-translatability. Following the rules of defining for an axiomatized theory was supposed to ensure satisfaction of the two conditions. But Tarski neither explained the two conditions nor supplied rules of defining for any axiomatized theory. We can make explicit what Tarski understood by consistency and back-translatability, with (...)
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  23. A General Schema for Bilateral Proof Rules.Ryan Simonelli - 2024 - Journal of Philosophical Logic (3):1-34.
    Bilateral proof systems, which provide rules for both affirming and denying sentences, have been prominent in the development of proof-theoretic semantics for classical logic in recent years. However, such systems provide a substantial amount of freedom in the formulation of the rules, and, as a result, a number of different sets of rules have been put forward as definitive of the meanings of the classical connectives. In this paper, I argue that a single general schema for bilateral proof rules has (...)
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  24. Some Ways the Ways the World Could Have Been Can't Be.Christopher James Masterman - 2024 - Journal of Philosophical Logic:1-29.
    Let serious propositional contingentism (SPC) be the package of views which consists in (i) the thesis that propositions expressed by sentences featuring terms depend, for their existence, on the existence of the referents of those terms, (ii) serious actualism—the view that it is impossible for an object to exemplify a property and not exist—and (iii) contingentism—the view that it is at least possible that some thing might not have been something. SPC is popular and compelling. But what should we say (...)
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