19 found
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  1. Topics of Thought. The Logic of Knowledge, Belief, Imagination.Franz Berto, Peter Hawke & Aybüke Özgün - 2022 - Oxford: Oxford University Press.
    When one thinks—knows, believes, imagines—that something is the case, one’s thought has a topic: it is about something, towards which one’s mind is directed. What is the logic of thought, so understood? This book begins to explore the idea that, to answer the question, we should take topics seriously. It proposes a hyperintensional account of the propositional contents of thought, arguing that these are individuated not only by the set of possible worlds at which they are true, but also by (...)
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  2. Dynamic Hyperintensional Belief Revision.Aybüke Özgün & Francesco Berto - 2021 - Review of Symbolic Logic (3):766-811.
    We propose a dynamic hyperintensional logic of belief revision for non-omniscient agents, reducing the logical omniscience phenomena affecting standard doxastic/epistemic logic as well as AGM belief revision theory. Our agents don’t know all a priori truths; their belief states are not closed under classical logical consequence; and their belief update policies are such that logically or necessarily equivalent contents can lead to different revisions. We model both plain and conditional belief, then focus on dynamic belief revision. The key idea we (...)
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  3. The Fundamental Problem of Logical Omniscience.Peter Hawke, Aybüke Özgün & Francesco Berto - 2020 - Journal of Philosophical Logic 49 (4):727-766.
    We propose a solution to the problem of logical omniscience in what we take to be its fundamental version: as concerning arbitrary agents and the knowledge attitude per se. Our logic of knowledge is a spin-off from a general theory of thick content, whereby the content of a sentence has two components: an intension, taking care of truth conditions; and a topic, taking care of subject matter. We present a list of plausible logical validities and invalidities for the logic of (...)
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  4. Indicative Conditionals: Probabilities and Relevance.Franz Berto & Aybüke Özgün - 2021 - Philosophical Studies (11):3697-3730.
    We propose a new account of indicative conditionals, giving acceptability and logical closure conditions for them. We start from Adams’ Thesis: the claim that the acceptability of a simple indicative equals the corresponding conditional probability. The Thesis is widely endorsed, but arguably false and refuted by empirical research. To fix it, we submit, we need a relevance constraint: we accept a simple conditional 'If φ, then ψ' to the extent that (i) the conditional probability p(ψ|φ) is high, provided that (ii) (...)
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  5. The Logic of Framing Effects.Francesco Berto & Aybüke Özgün - 2023 - Journal of Philosophical Logic 52 (3):939-962.
    _Framing effects_ concern the having of different attitudes towards logically or necessarily equivalent contents. Framing is of crucial importance for cognitive science, behavioral economics, decision theory, and the social sciences at large. We model a typical kind of framing, grounded in (i) the structural distinction between beliefs activated in working memory and beliefs left inactive in long term memory, and (ii) the topic- or subject matter-sensitivity of belief: a feature of propositional attitudes which is attracting growing research attention. We introduce (...)
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  6. Truthmaker Semantics for Epistemic Logic.Peter Hawke & Aybüke Özgün - 2023 - In Federico L. G. Faroldi & Frederik Van De Putte (eds.), Kit Fine on Truthmakers, Relevance, and Non-classical Logic. Springer Verlag. pp. 295-335.
    We explore some possibilities for developing epistemic logic using truthmaker semantics. We identify three possible targets of analysis for the epistemic logician. We then list some candidate epistemic principles and review the arguments that render some controversial. We then present the classic Hintikkan approach to epistemic logic and note—as per the ‘problem of logical omniscience’—that it validates all of the aforementioned principles, controversial or otherwise. We then lay out a truthmaker framework in the style of Kit Fine and present six (...)
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  7. The Method of Thought Experiments: Probability and Counterfactuals.Francesco Berto & Aybüke Özgün - forthcoming - Journal of Philosophy.
    We find a simple counterfactual acceptable, it is argued, to the extent that (i) our probability of the consequent under the thought experiment of counterfactually supposing the antecedent is high, (ii) provided the latter is on-topic with respect to the former. Counterfactual supposition is represented by Lewisian imaging. Topicality, by an algebra of subject matters. A topic-sensitive probabilistic logic is then provided, to reason about the acceptability of simple counterfactuals.
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  8. A hyperintensional approach to positive epistemic possibility.Niccolò Rossi & Aybüke Özgün - 2023 - Synthese 202 (44):1-29.
    The received view says that possibility is the dual of necessity: a proposition is (metaphysically, logically, epistemically etc.) possible iff it is not the case that its negation is (metaphysically, logically, epistemically etc., respectively) necessary. This reading is usually taken for granted by modal logicians and indeed seems plausible when dealing with logical or metaphysical possibility. But what about epistemic possibility? We argue that the dual definition of epistemic possibility in terms of epistemic necessity generates tension when reasoning about non-idealized (...)
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  9.  70
    A Topological Approach to Full Belief.Alexandru Baltag, Nick Bezhanishvili, Aybüke Özgün & Sonja Smets - 2019 - Journal of Philosophical Logic 48 (2):205-244.
    Stalnaker, 169–199 2006) introduced a combined epistemic-doxastic logic that can formally express a strong concept of belief, a concept of belief as ‘subjective certainty’. In this paper, we provide a topological semantics for belief, in particular, for Stalnaker’s notion of belief defined as ‘epistemic possibility of knowledge’, in terms of the closure of the interior operator on extremally disconnected spaces. This semantics extends the standard topological interpretation of knowledge with a new topological semantics for belief. We prove that the belief (...)
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  10.  66
    Logic and Topology for Knowledge, Knowability, and Belief.Adam Bjorndahl & Aybüke Özgün - 2020 - Review of Symbolic Logic 13 (4):748-775.
    In recent work, Stalnaker proposes a logical framework in which belief is realized as a weakened form of knowledge. Building on Stalnaker’s core insights, we employ topological tools to refine and, we argue, improve on this analysis. The structure of topological subset spaces allows for a natural distinction between what is known and what is knowable; we argue that the foundational axioms of Stalnaker’s system rely intuitively on both of these notions. More precisely, we argue that the plausibility of the (...)
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  11.  62
    Announcement as effort on topological spaces.Hans van Ditmarsch, Sophia Knight & Aybüke Özgün - 2019 - Synthese 196 (7):2927-2969.
    We propose a multi-agent logic of knowledge, public announcements and arbitrary announcements, interpreted on topological spaces in the style of subset space semantics. The arbitrary announcement modality functions similarly to the effort modality in subset space logics, however, it comes with intuitive and semantic differences. We provide axiomatizations for three logics based on this setting, with S5 knowledge modality, and demonstrate their completeness. We moreover consider the weaker axiomatizations of three logics with S4 type of knowledge and prove soundness and (...)
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  12.  56
    (1 other version)The Logical Development of Pretense Imagination.Aybüke Özgün & Tom Schoonen - 2022 - Erkenntnis:1-27.
    We propose a logic of imagination, based on simulated belief revision, that intends to uncover the logical patterns governing the development of imagination in pretense. Our system complements the currently prominent logics of imagination in that ours in particular formalises (1) the algorithm that specifies what goes on in between receiving a certain input for an imaginative episode and what is imagined in the resulting imagination, as well as (2) the goal-orientedness of imagination, by allowing the context to determine, what (...)
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  13.  31
    Justified belief, knowledge, and the topology of evidence.Sonja Smets, Aybüke Özgün, Nick Bezhanishvili & Alexandru Baltag - 2022 - Synthese 200 (6):1-51.
    We propose a new topological semantics for evidence, evidence-based justifications, belief, and knowledge. Resting on the assumption that an agent’s rational belief is based on the available evidence, we try to unveil the concrete relationship between an agent’s evidence, belief, and knowledge via a rich formal framework afforded by topologically interpreted modal logics. We prove soundness, completeness, decidability, and the finite model property for the associated logics, and apply this setting to analyze key epistemological issues such as “no false lemma” (...)
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  14.  19
    Announcement as effort on topological spaces.Aybüke Özgün, Sophia Knight & Hans Ditmarsch - 2019 - Synthese 196 (7):2927-2969.
    We propose a multi-agent logic of knowledge, public announcements and arbitrary announcements, interpreted on topological spaces in the style of subset space semantics. The arbitrary announcement modality functions similarly to the effort modality in subset space logics, however, it comes with intuitive and semantic differences. We provide axiomatizations for three logics based on this setting, with S5 knowledge modality, and demonstrate their completeness. We moreover consider the weaker axiomatizations of three logics with S4 type of knowledge and prove soundness and (...)
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  15.  42
    Dynamic hyperintensional belief revision—erratum.Aybüke Özgün & Francesco Berto - forthcoming - Review of Symbolic Logic:1-1.
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  16.  39
    Correction to: A hyperintensional approach to positive epistemic possibility.Niccolò Rossi & Aybüke Özgün - 2023 - Synthese 202 (3):1-1.
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  17.  54
    Private Announcements on Topological Spaces.Hans van Ditmarsch, Sophia Knight & Aybüke Özgün - 2018 - Studia Logica 106 (3):481-513.
    In this work, we present a multi-agent logic of knowledge and change of knowledge interpreted on topological structures. Our dynamics are of the so-called semi-private character where a group G of agents is informed of some piece of information \, while all the other agents observe that group G is informed, but are uncertain whether the information provided is \ or \. This article follows up on our prior work where the dynamics were public events. We provide a complete axiomatization (...)
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  18.  33
    Arbitrary Public Announcement Logic with Memory.Alexandru Baltag, Aybüke Özgün & Ana Lucia Vargas Sandoval - 2022 - Journal of Philosophical Logic 52 (1):53-110.
    We introduce Arbitrary Public Announcement Logic with Memory (APALM), obtained by adding to the models a ‘memory’ of the initial states, representing the information before any communication took place (“the prior”), and adding to the syntax operators that can access this memory. We show that APALM is recursively axiomatizable (in contrast to the original Arbitrary Public Announcement Logic, for which the corresponding question is still open). We present a complete recursive axiomatization, that includes a natural finitary rule, and study this (...)
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  19.  19
    Private Announcements on Topological Spaces.Aybüke Özgün, Sophia Knight & Hans Ditmarsch - 2018 - Studia Logica 106 (3):481-513.
    In this work, we present a multi-agent logic of knowledge and change of knowledge interpreted on topological structures. Our dynamics are of the so-called semi-private character where a group G of agents is informed of some piece of information $$\varphi $$ φ, while all the other agents observe that group G is informed, but are uncertain whether the information provided is $$\varphi $$ φ or $$\lnot \varphi $$ ¬φ. This article follows up on our prior work where the dynamics were (...)
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