Impossible Worlds

This is an open access title available under the terms of a CC BY-NC-ND 4.0 International licence. It is free to read at Oxford Scholarship Online and offered as a free PDF download from OUP and selected open access locations. 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 without collapsing into total incoherence. Yet for the leading philosophical theories of meaning, these phenomena are an unfathomable mystery. To understand these concepts, we need a metaphysical, logical, and conceptual grasp of situations that could not possibly exist: Impossible Worlds. This book discusses the metaphysics of impossible worlds and applies the concept to a range of central topics and open issues in logic, semantics, and philosophy. It considers problems in the logic of knowledge, the meaning of alternative logics, models of imagination and mental simulation, the theory of information, truth in fiction, the meaning of conditional statements, and reasoning about the impossible. In all these cases, impossible worlds have an essential role to play. Cover Impossible Worlds Copyright Dedication Contents Introduction Outline of the Book Acknowledgements Part I. Impossibilities 1. From Possible to Impossible Worlds 1.1 Worlds as Ways 1.2 Possible Worlds at Work Possibility and Necessity Propositions Knowledge and Belief Information Indicative Conditionals Counterfactual Conditionals 1.3 The Problem(s) of Hyperintensionality Propositions: Triviality Knowledge and Belief: Logical Omniscience Information: Triviality and Overload Indicative Conditionals: Irrelevance Counterfactual Conditionals: Counterpossibles 1.4 Impossible Worlds 1.5 Conceivability and Possibility Chapter Summary 2. Metaphysics 2.1 Ways of Thinking about Worlds 2.2 Genuine Realism Lewisian Realism Yagisawaian Realism McDanielian Realism 2.3 Non-existent Worlds 2.4 Ersatz Modal Realism 2.5 The Hybrid View 2.6 Encoding Worlds 2.7 Primitivism about Worlds 2.8 Fictionalism Chapter Summary 3. Ersatz Modal Realism 3.1 Classifying Ersatz Theories 3.2 Maximal States of Affairs 3.3 Property Ersatzism 3.4 Combinatorial Ersatzism 3.5 Map Ersatzism 3.6 Propositional and Linguistic Ersatzism 3.7 Alien Entities Chapter Summary Part II. Logical Applications 4. Modal Logics 4.1 Normal Modal Logics 4.2 Non-Normal Modal Logics 4.3 Non-Uniform Truth Conditions 4.4 Non-Adjunctive and Non-Prime Worlds Chapter Summary 5. Epistemic Logics 5.1 Standard Epistemic Logic and Logical Omniscience 5.2 Dealing with Omniscience without Impossible Worlds 5.3 Impossible Worlds for Knowledge and Belief 5.4 Closure under a Weaker Logic 5.5 Going Dynamic Chapter Summary 6. Relevant Logics 6.1 Basic Relevant Logic 6.2 Stronger Relevant Logics 6.3 Relevant Worlds as Information States 6.4 Conditionality Interpretations 6.5 The Truthmaking Interpretation Chapter Summary 7. The Logic of Imagination 7.1 Hyperintensional Imagination 7.2 A Semantics of Imagination 7.3 The Mereology of Imagination 7.4 The Under-Determinacy of Imagination 7.5 Non-Monotonicity and Relevance 7.6 Imaginative Equivalents Chapter Summary Part III. Philosophical Applications 8. Hyperintensionality 8.1 Is Hyperintensionality Real? 8.2 The Epistemic Case 8.3 The Case from Content 8.4 The Granularity Issue 8.5 The Compositionality Objection Chapter Summary 9. Information and Content 9.1 Informative Statements 9.2 Information as Ruling Out Scenarios 9.3 Informative Identities 9.4 Informative Inference 9.5 Vague Logical Information 9.6 What Is Said Chapter Summary 10. Epistemic and Doxastic Contents 10.1 Belief States 10.2 The Impossible Worlds Approach 10.3 The Problem of Bounded Rationality 10.4 Bounded Rationality and Vagueness 10.5 Belief and Trivial Inference 10.6 Believing Contradictions Chapter Summary 11.Fiction and Fictional Objects 11.1 Problems of Fiction 11.2 Truth in Fiction 11.3 Hyperintensional Fictions 11.4 A Formal Semantics 11.5 Realism and Fictionalism about Fictional Entities 11.6 Non-existent Objects and Impossible Worlds Chapter Summary 12. Counterpossible Conditionals 12.1 Why Counterpossibles? 12.2 A Semantics for Counterpossibles 12.3 The Strangeness of Impossibility Condition 12.4 Substitutivity of Identicals 12.5 Reductio Arguments 12.6 Intuitions for Non-Vacuism Thinking it Through A Heuristic? Vacuous Quantification Chapter Summary Bibliography Index Пустая страница Пустая страница The latter half of the 20th Century witnessed an ?intensional revolution?: a great collective effort to analyse notions which are absolutely fundamental to our understanding of the world and of ourselves ? from meaning and information to knowledge, belief, causation, essence, supervenience, conditionality, as well as nomological, metaphysical, and logical necessity ? in terms of a single concept. This was the concept of a possible world: a way things could have been. Possible worlds found applications in logic, metaphysics, semantics, game theory, information theory, artificial intelligence, and the philosophy of mind and cognition. However, possible worlds analyses have been facing numerous problems. This book traces them all back to hyperintensionality: the need for distinctions more fine-grained than the possible worlds apparatus can easily represent. It then introduces impossible worlds ? ways things could not have been ? as a general tool for modelling hyperintensional phenomena. The book discusses the metaphysics of impossible worlds and applies them to a range of central topics and open issues in logic, semantics, and philosophy: from the problem of logical omniscience in epistemic logic, to the semantics of non-classical logics, the modeling of imagination and mental simulation, the analysis of information and informative inference, truth in fiction, and counterpossible reasoning. The latter half of the 20th Century witnessed an ?intensional revolution?: a great collective effort to analyse notions which are absolutely fundamental to our understanding of the world and of ourselves ? from meaning and information to knowledge, belief, causation, essence, supervenience, conditionality, as well as nomological, metaphysical, and logical necessity ? in terms of a single concept. This was the concept of a possible world: a way things could have been. Possible worlds found applications in logic, metaphysics, semantics, game theory, information theory, artificial intelligence, and the philosophy of mind and cognition. However, possible worlds analyses have been facing numerous problems. This book traces them all back to hyperintensionality: the need for distinctions more fine-grained than the possible worlds apparatus can easily represent. It then introduces impossible worlds ? ways things could not have been ? as a general tool for modelling hyperintensional phenomena. The book discusses the metaphysics of impossible worlds and applies them to a range of central topics and open issues in logic, semantics, and philosophy: from the problem of logical omniscience in epistemic logic, to the semantics of non-classical logics, the modeling of imagination and mental simulation, the analysis of information and informative inference, truth in fiction, and counterpossible reasoning. This is an open access title available under the terms of a CC BY-NC-ND 4.0 International licence. It is free to read at Oxford Scholarship Online and offered as a free PDF download from OUP and selected open access locations.0We 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 things0without collapsing into total incoherence. Yet for the leading philosophical theories of meaning, these phenomena are an unfathomable mystery. To understand these concepts, we need a metaphysical, logical, and conceptual grasp of situations that could not possibly exist: Impossible Worlds. This book discusses the metaphysics of impossible worlds and applies the concept to a range of central topics and open issues in logic, semantics, and philosophy. It considers problems in the logic of knowledge, the meaning of alternative logics, models of imagination and mental simulation, the theory of information, truth in fiction, the meaning of conditional statements, and reasoning about the impossible. In all these cases, impossible worlds have an essential role to play Presentación del editor: "The latter half of the twentieth century witnessed an 'intensional revolution', a great collective effort to analyse notions which are absolutely fundamental to our understanding of the world and of ourselves--from meaning and information to knowledge, belief, causation, essence, supervenience, conditionality, as well as nomological, metaphysical, and logical necessity--in terms of a single concept. This was the concept of a possible world: a way things could have been. Possible worlds found applications in logic, metaphysics, semantics, game theory, information theory, artificial intelligence, and the philosophy of mind and cognition. However, possible worlds analyses have been facing numerous problems. This book traces them all back to hyperintensionality: the need for distinctions more fine-grained than the possible worlds apparatus can easily represent. It then introduces impossible worlds--ways things could not have been--as a general tool for modelling hyperintensional phenomena. The book discusses the metaphysics of impossible worlds and applies them to a range of central topics and open issues in logic, semantics, and philosophy: from the problem of logical omniscience in epistemic logic, to the semantics of non-classical logics, the modelling of imagination and mental simulation, the analysis of information and informative inference, truth in fiction, and counterpossible reasoning." Berto and Jago question how to understand the impossible without collapsing into total incoherence. By considering the metaphysics of impossible worlds - and applying this concept to issues in logic, semantics, and philosophy - they offer a framework for obtaining a metaphysical, logical, and conceptual grasp of situations that simply cannot be