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709Simple Hyperintensional Belief RevisionErkenntnis 84 (3): 559-575. 2019.I present a possible worlds semantics for a hyperintensional belief revision operator, which reduces the logical idealization of cognitive agents affecting similar operators in doxastic and epistemic logics, as well as in standard AGM belief revision theory. (Revised) belief states are not closed under classical logical consequence; revising by inconsistent information does not perforce lead to trivialization; and revision can be subject to ‘framing effects’: logically or necessarily equivalent …Read more
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700To exist and to count: A note on the minimalist viewDialectica 63 (3): 343-356. 2009.Sometimes mereologists have problems with counting. We often don't want to count the parts of maximally connected objects as full-fledged objects themselves, and we don't want to count discontinuous objects as parts of further, full-fledged objects. But whatever one takes "full-fledged object" to mean, the axioms and theorems of classical, extensional mereology commit us to the existence both of parts and of wholes – all on a par, included in the domain of quantification – and this makes mereolo…Read more
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693Williamson on CounterpossiblesJournal of Philosophical Logic 47 (4): 693-713. 2018.A counterpossible conditional is a counterfactual with an impossible antecedent. Common sense delivers the view that some such conditionals are true, and some are false. In recent publications, Timothy Williamson has defended the view that all are true. In this paper we defend the common sense view against Williamson’s objections.
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660Topics of Thought. The Logic of Knowledge, Belief, ImaginationOxford University Press. 2022.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 their…Read more
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650The Logic of Fast and Slow ThinkingErkenntnis 86 (3): 733-762. 2019.We present a framework for epistemic logic, modeling the logical aspects of System 1 and System 2 cognitive processes, as per dual process theories of reasoning. The framework combines non-normal worlds semantics with the techniques of Dynamic Epistemic Logic. It models non-logically-omniscient, but moderately rational agents: their System 1 makes fast sense of incoming information by integrating it on the basis of their background knowledge and beliefs. Their System 2 allows them to slowly, ste…Read more
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607The Logic of Framing EffectsJournal of Philosophical Logic 52 (3): 939-962. 2023._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…Read more
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571Non-Normal Worlds and RepresentationIn Michal Peliš & Vít Punčochář (eds.), The Logica Yearbook, College Publications. 2012.World semantics for relevant logics include so-called non-normal or impossible worlds providing model-theoretic counterexamples to such irrelevant entailments as (A ∧ ¬A) → B, A → (B∨¬B), or A → (B → B). Some well-known views interpret non-normal worlds as information states. If so, they can plausibly model our ability of conceiving or representing logical impossibilities. The phenomenon is explored by combining a formal setting with philosophical discussion. I take Priest’s basic relevant logic…Read more
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555Dynamic Hyperintensional Belief RevisionReview of Symbolic Logic (3): 766-811. 2021.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, …Read more
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547The Selection ProblemRevue Internationale de Philosophie 262 (4): 519-537. 2012.In 'Fiction and Fictionalism', Mark Sainsbury has recently dubbed “Selection Problem” a serious trouble for Meinongian object theories. Typically, Meinongianism has been phrased as a kind of realism on nonexistent objects : these are mind-independent things, not mental simulacra, having the properties they have independently from the activity of any cognitive agent. But how can one single out an object we have no causal acquaintance with, and which is devoid of spatiotemporal location, picking i…Read more
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525Modal Meinongianism and Object TheoryAustralasian Journal of Logic 17 (1): 1-21. 2020.We reply to various arguments by Otavio Bueno and Edward Zalta (‘Object Theory and Modal Meinongianism’) against Modal Meinongianism, including that it presupposes, but cannot maintain, a unique denotation for names of fictional characters, and that it is not generalizable to higher-order objects. We individuate the crucial difference between Modal Meinongianism and Object Theory in the former’s resorting to an apparatus of worlds, possible and impossible, for the representational purposes for w…Read more
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499There’s Plenty of Boole at the Bottom: A Reversible CA Against Information EntropyMinds and Machines 26 (4): 341-357. 2016.“There’s Plenty of Room at the Bottom”, said the title of Richard Feynman’s 1959 seminal conference at the California Institute of Technology. Fifty years on, nanotechnologies have led computer scientists to pay close attention to the links between physical reality and information processing. Not all the physical requirements of optimal computation are captured by traditional models—one still largely missing is reversibility. The dynamic laws of physics are reversible at microphysical level, dis…Read more
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459Truth, Topicality, and Transparency: One-Component Versus Two-Component SemanticsLinguistics and Philosophy. forthcoming.When do two sentences say the same thing, that is, express the same content? We defend two-component (2C) semantics: the view that propositional contents comprise (at least) two irreducibly distinct constituents, (1) truth-conditions, and (2) subject-matter. We contrast 2C with one-component (1C) semantics, focusing on the view that subject-matter is reducible to truth- conditions. We identify exponents of this view and argue in favor of 2C. An appendix proposes a general formal template for pro…Read more
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441Hyperintensionality and OverfittingSynthese 1 (4): 1-21. 2024.A hyperintensional epistemic logic would take the contents which can be known or believed as more fine-grained than sets of possible worlds. I consider one objection to the idea: Williamson’s Objection from Overfitting. I propose a hyperintensional account of propositions as sets of worlds enriched with topics: what those propositions, and so the attitudes having them as contents, are about. I show that the account captures the conditions under which sentences express the same content; that it c…Read more
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426The Firmest of All PrinciplesIn Channa van Dijk, Eva van der Graaf, Michiel den Haan, Rosa de Jong, Christiaan Roodenburg, Dyane Til & Deva Waal (eds.), Under Influence - Philosophical Festival Drift (2014), Omnia. pp. 82-93. 2015.
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340Adding 4.0241 to TLPIn Gabriele Mras, Paul Weingartner & Bernhard Ritter (eds.), Philosophy of Logic and Mathematics: Proceedings of the 41st International Ludwig Wittgenstein Symposium, De Gruyter. pp. 415-428. 2019.Tractatus 4.024 inspired the dominant semantics of our time: truth-conditional semantics. Such semantics is focused on possible worlds: the content of p is the set of worlds where p is true. It has become increasingly clear that such an account is, at best, defective: we need an ‘independent factor in meaning, constrained but not determined by truth-conditions’ (Yablo 2014, p. 2), because sentences can be differently true at the same possible worlds. I suggest a missing comment which, had it bee…Read more
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318DialetheismStanford Encyclopedia of Philosophy 2018 (2018). 2008.A dialetheia is a sentence, A, such that both it and its negation, ¬A, are true (we shall talk of sentences throughout this entry; but one could run the definition in terms of propositions, statements, or whatever one takes as her favourite truth-bearer: this would make little difference in the context). Assuming the fairly uncontroversial view that falsity just is the truth of negation, it can equally be claimed that a dialetheia is a sentence which is both true and false
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272Meaning, Metaphysics, and ContradictionAmerican Philosophical Quarterly 43 (4): 283-297. 2006.None
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260Modal Meinongianism for Fictional ObjectsMetaphysica 9 (2): 205-218. 2008.Drawing on different suggestions from the literature, we outline a unified metaphysical framework, labeled as Modal Meinongian Metaphysics (MMM), combining Meinongian themes with a non-standard modal ontology. The MMM approach is based on (1) a comprehension principle (CP) for objects in unrestricted, but qualified form, and (2) the employment of an ontology of impossible worlds, besides possible ones. In §§1–2, we introduce the classical Meinongian metaphysics and consider two famous Russellia…Read more
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206How to Sell a Contradiction: The Logic and Metaphysics of InconsistencyCollege Publications. 2007.There is a principle in things, about which we cannot be deceived, but must always, on the contrary, recognize the truth – viz. that the same thing cannot at one and the same time be and not be": with these words of the Metaphysics, Aristotle introduced the Law of Non-Contradiction, which was to become the most authoritative principle in the history of Western thought. However, things have recently changed, and nowadays various philosophers, called dialetheists, claim that this Law does not hold…Read more
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195Cellular automataStanford Encyclopedia of Philosophy -. 2012.Cellular automata (henceforth: CA) are discrete, abstract computational systems that have proved useful both as general models of complexity and as more specific representations of non-linear dynamics in a variety of scientific fields. Firstly, CA are (typically) spatially and temporally discrete: they are composed of a finite or denumerable set of homogeneous, simple units, the atoms or cells. At each time unit, the cells instantiate one of a finite set of states. They evolve in parallel at dis…Read more
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164Impossible WorldsOxford University Press. 2013.We need to understand the impossible. Francesco Berto and Mark Jago start by considering what the concepts of meaning, information, knowledge, belief, fiction, conditionality, and counterfactual supposition have in common. They are all concepts which divide the world up more finely than logic does. Logically equivalent sentences may carry different meanings and information and may differ in how they're believed. Fictions can be inconsistent yet meaningful. We can suppose impossible things withou…Read more
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158There's Something About Gdel: The Complete Guide to the Incompleteness TheoremWiley-Blackwell. 2009.Berto’s highly readable and lucid guide introduces students and the interested reader to Gödel’s celebrated _Incompleteness Theorem_, and discusses some of the most famous - and infamous - claims arising from Gödel's arguments. Offers a clear understanding of this difficult subject by presenting each of the key steps of the _Theorem_ in separate chapters Discusses interpretations of the _Theorem_ made by celebrated contemporary thinkers Sheds light on the wider extra-mathematical and philosophic…Read more
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118Taming the runabout imagination ticketSynthese (Suppl 8): 2029-2043. 2018.This research is published within the project ‘The Logic of Conceivability’, funded by the European Research Council, Grant Number 681404.
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109Counting the Particles: Entity and Identity in the Philosophy of PhysicsMetaphysica 18 (1): 69-89. 2017.I would like to attack a certain view: The view that the concept of identity can fail to apply to some things although, for some positive integer n, we have n of them. The idea of entities without self-identity is seriously entertained in the philosophy of quantum mechanics. It is so pervasive that it has been labelled the Received View. I introduce the Received View in Section 1. In Section 2 I explain what I mean by entity, and I argue that supporters of the Received View should agree with my …Read more
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94Impossible WorldsOxford University Press. 2019.Impossible Worlds focuses on an exciting new theory in philosophy, with applications in metaphysics, logic, and the theory of meaning. Its central topic is: how do we meaningfully talk and reason about situations which, unbeknownst to us, are impossible? This issue emerges as a central problem in contemporary philosophical accounts of meaning, information, knowledge, belief, fiction, conditionality, and counterfactual supposition. The book is written bytwo of the leading philosophers in the area…Read more
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69Wittgenstein on Incompleteness Makes Paraconsistent SenseIn Francesco Berto, Edwin Mares, Koji Tanaka & Francesco Paoli (eds.), Paraconsistency: Logic and Applications, Springer. pp. 257--276. 2008.I provide an interpretation of Wittgenstein's much criticized remarks on Gödel's First Incompleteness Theorem in the light of paraconsistent arithmetics: in taking Gödel's proof as a paradoxical derivation, Wittgenstein was right, given his deliberate rejection of the standard distinction between theory and metatheory. The reasoning behind the proof of the truth of the Gödel sentence is then performed within the formal system itself, which turns out to be inconsistent. I show that the models of …Read more
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68Guest editors' introductionLogic and Logical Philosophy 19 (1-2): 5-6. 2010.A logic is said to be paraconsistent if it doesn’t license you to infer everything from a contradiction. To be precise, let |= be a relation of logical consequence. We call |= explosive if it validates the inference rule: {A,¬A} |= B for every A and B. Classical logic and most other standard logics, including intuitionist logic, are explosive. Instead of licensing you to infer everything from a contradiction, paraconsistent logic allows you to sensibly deal with the contradiction
St Andrews, United Kingdom of Great Britain and Northern Ireland
Areas of Specialization
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Logic and Philosophy of Logic |
Formal Epistemology |
Doxastic and Epistemic Logic |
Metaphysics |
Modality |
Metaontology |
Philosophy of Computing and Information |