The standard view about counterfactuals is that a counterfactual (A > C) is true if and only if the A-worlds most similar to the actual world @ are C-worlds. I argue that the worlds conception of counterfactuals is wrong. I assume that counterfactuals have non-trivial truth-values under physical determinism. I show that the possible-worlds approach cannot explain many embeddings of the form (P > (Q > R)), which intuitively are perfectly assertable, and which must be (...) true if the contingent falsity of (Q > R) is to be explained. If (P > (Q > R)) has a backtracking reading then the contingent facts that (Q > R) needs to be true in the closest P-worlds are absent. If (P > (Q > R)) has a forwardtracking reading, then the laws required by (Q > R) to be true in the closest P-worlds will be absent, because they are violated in those worlds. Solutions like lossy laws or denial of embedding won't work. The only approach to counterfactuals that explains the embedding is a pragmatic metalinguistic approach in which the whole idea that counterfactuals are about a modal reality, be it abstract or concrete, is given up. (shrink)
Among the most remarkable developments in metaphysics since the 1950’s is the explosion of philosophical interest in possibleworlds. This paper proposes an explanation of what possibleworlds are, and argues that this proposal, the interpreted models conception, should be attractive to anyone who thinks that modal facts are primitive, and so not to be explained in terms of some non-modal notion of “possible world.” I articulate three constraints on any acceptable primitivist explanation of the (...) nature of possibleworlds, and show that the interpreted models conception meets the three constraints. (shrink)
How do ordinary objects persist through time and across possibleworlds ? How do they manage to have their temporal and modal properties ? These are the questions adressed in this book which is a "guided tour of theories of persistence". The book is divided in two parts. In the first, the two traditional accounts of persistence through time (endurantism and perdurantism) are combined with presentism and eternalism to yield four different views, and their variants. The resulting views (...) are then examined in turn, in order to see which combinations are appealing and which are not. It is argued that the 'worm view' variant of eternalist perdurantism is superior to the other alternatives. In the second part of the book, the same strategy is applied to the combinations of views about persistence across possibleworlds (trans-world identity, counterpart theory, modal perdurants) and views about the nature of worlds, mainly modal realism and abstractionism. Not only all the traditional and well-known views, but also some more original ones, are examined and their pros and cons are carefully weighted. Here again, it is argued that perdurance seems to be the best strategy available. (shrink)
The most commonly heard proposals for reducing possibleworlds to language succumb to a simple cardinality argument: it can be shown that there are more possibleworlds than there are linguistic entities provided by the proposal. In this paper, I show how the standard proposals can be generalized in a natural way so as to make better use of the resources available to them, and thereby circumvent the cardinality argument. Once it is seen just what the (...) limitations are on these more general proposals, it can be clearly seen where the real difficulty lies with any attempt to reduce possibleworlds to language. Roughly, the difficulty is this: no actual language could have the descriptive resources needed to represent all the ways things might have been. I conclude by arguing that this same difficulty spells doom for any nominalist or conceptualist proposal for reducing possibleworlds. (shrink)
If realism about possibleworlds is to succeed in eliminating primitive modality, it must provide an 'analysis' of possible world: nonmodal criteria for demarcating one world from another. This David Lewis has done. Lewis holds, roughly, that worlds are maximal unified regions of logical space. So far, so good. But what Lewis means by 'unification' is too narrow, I think, in two different ways. First, for Lewis, all worlds are (almost) 'globally' unified: at any world, (...) (almost) every part is directly linked to (almost) every other part. I hold instead that some worlds are 'locally' unified: at some worlds, parts are directly linked only to "neighboring" parts. Second, for Lewis, each world is (analogically) 'spatio-temporally' unified; every world is 'spatio-temporally' isolated from every other. I hold instead: a world may be unified by nonspatio-temporal relations; every world is 'absolutely' isolated from every other. If I am right, Lewis's conception of logical space is impoverished: perfectly respectable worlds are missing. (shrink)
I outline a neo-Fregean strategy in the debate on the existence of possibleworlds. The criterion of identity and the criterion of application are formulated. Special attention is paid to the fact that speakers do not possess proper names for worlds. A broadly Quinean solution is proposed in response to this difficulty.
We show that, given standard assumptions about classical dynamical systems, Lewis' conception of possibleworlds is incompatible with classical physics in that it would imply that all dynamical systems were integrable.
The role of possibleworlds in philosophy is hard to overestimate. Nevertheless, their nature and existence is very controversial. This is particularly serious, since their standard applications depend on there being sufficiently many of them. The paper develops an account of possibleworlds on which it is particularly easy to believe in their existence: an account of possibleworlds as pleonastic entities. Pleonastic entities are entities whose existence can be validly inferred from statements that (...) neither refer to nor quantify over them as a matter of conceptual necessity. Definitions are proposed that ensure that this is the case for possibleworlds. (shrink)
If □ is conceived as an operator, i.e., an expression that gives applied to a formula another formula, the expressive power of the language is severely restricted when compared to a language where □ is conceived as a predicate, i.e., an expression that yields a formula if it is applied to a term. This consideration favours the predicate approach. The predicate view, however, is threatened mainly by two problems: Some obvious predicate systems are inconsistent, and possible-worlds semantics for (...) predicates of sentences has not been developed very far. By introducing possible-worlds semantics for the language of arithmetic plus the unary predicate □, we tackle both problems. Given a frame (W, R) consisting of a set W of worlds and a binary relation R on W, we investigate whether we can interpret □ at every world in such a way that □ $\ulcorner A \ulcorner$ holds at a world ᵆ ∊ W if and only if A holds at every world $\upsilon$ ∊ W such that ᵆR $\upsilon$ . The arithmetical vocabulary is interpreted by the standard model at every world. Several 'paradoxes' (like Montague's Theorem, Gödel's Second Incompleteness Theorem, McGee's Theorem on the ω-inconsistency of certain truth theories, etc.) show that many frames, e.g., reflexive frames, do not allow for such an interpretation. We present sufficient and necessary conditions for the existence of a suitable interpretation of □ at any world. Sound and complete semi-formal systems, corresponding to the modal systems K and K4, for the class of all possible-worlds models for predicates and all transitive possible-worlds models are presented. We apply our account also to nonstandard models of arithmetic and other languages than the language of arithmetic. (shrink)
The paper is a brief survey of the most important semantic constructions founded on the concept of possible world. It is impossible to capture in one short paper the whole variety of the problems connected with manifold applications of possibleworlds. Hence, after a brief explanation of some philosophical matters I take a look at possibleworlds from rather technical standpoint of logic and focus on the applications in formal semantics. In particular, I would like (...) to focus on the fruitful marriage of possible world semantics and algebra and its evolution leading to very general construction of Wójcicki called referential semantics and some of its refinements. The presentation is informal and sketchy; the main purpose is to put in one place a short, and readable I hope, description of the most important constructions and to point out the main sources of these solutions. (shrink)
The article investigates the sceptical challenge from an informationtheoretic perspective. Its main goal is to articulate and defend the view that either informational scepticism is radical, but then it is epistemologically innocuous because redundant; or it is moderate, but then epistemologically beneficial because useful. In order to pursue this cooptation strategy, the article is divided into seven sections. Section 1 sets up the problem. Section 2 introduces Borei numbers as a convenient way to refer uniformly to (the data that individuate) (...) different possibleworlds. Section 3 adopts the Hamming distance between Borei numbers as a metric to calculate the distance between possibleworlds. In Sects. 4 and 5, radical and moderate informational scepticism are analysed using Borei numbers and Hamming distances, and shown to be either harmless (extreme form) or actually fruitful (moderate form). Section 6 further clarifies the approach by replying to some potential objections. In the conclusion, the Peircean nature of the overall approach is briefly discussed. (shrink)
Of late, evidentiality has received great attention in formal semantics. In this paper I develop ‘evidentiality-informed’ truth conditions for modal operators such as must and may . With language data drawn from Luoping Nase (a Tibeto-Burman language spoken in the P.R. of China and belonging to the Yi Nationality), I illustrate that epistemic modals clash with clauses articulating first-hand information. I then demonstrate that existing models such as Kratzer’s graded possible-worlds semantics fail to provide accurate truth conditions for (...) modals tagging clauses with first-hand information. As a remedy I propose a fuzzy version of possible-worlds semantics with various grades of belief and knowledge. In addition to preserving the expressive power of graded possible-worlds semantics, the fuzzy model will be shown to supply appropriate truth conditions for epistemic modals appended to evidential clauses (i.e. clauses expressing first-hand information). (shrink)
In this paper I explore the relationship between the idea of possibleworlds and the notion of the beauty of God. I argue that there is a clear contradiction between the idea that God is utterly and completely beautiful on the one hand and the notion that He contains within himself all possibleworlds on the other. Since some of the possibleworlds residing in the mind of the deity are ugly, their presence seems (...) to compromise God's complete and utter beauty. (shrink)
In this paper, an argument of Alvin Plantinga's for the existence of abstract possibleworlds is shown to be unsound. The argument is based on a principle Plantinga calls "Quasicompactness", due to its structural similarity to the notion of compactness in first-order logic. The principle is shown to be false.
The question as to whether some objects are possibleworlds that have an initial segment in common, i.e. so that their fusion is a temporal tree whose branches are possibleworlds, arises both for those who hold that our universe has the structure of a temporal tree and for those who hold that what there is includes concrete universes of every possible variety. The notion of “possible world” employed in the question is seen to (...) be the notion of an object of a kind such that objects of that kind play a certain theoretical role. Lewis’s discussion of the question is thereby clarified but is nevertheless inadequate; his negative answer is correct but even from his combinatorialist viewpoint the rationale he provides for this answer is misguided. I explain why the combinatorialist advocate of concrete plenitude should hold that no object is a tree of possibleworlds. Then I explain that for a different reason the nomic essentialist advocate of concrete plenitude should hold this much too. (shrink)
This article includes a basic overview of possible world semantics and a relatively comprehensive overview of three central philosophical conceptions of possibleworlds: Concretism (represented chiefly by Lewis), Abstractionism (represented chiefly by Plantinga), and Combinatorialism (represented chiefly by Armstrong).
A century ago, Charles S. Peirce proposed a logical approach to modalities that came close to possible-worlds semantics. This paper investigates his views on modalities through his diagrammatic logic of Existential Graphs (EGs). The contribution of the gamma part of EGs to the study of modalities is examined. Some ramifications of Peirce’s remarks are presented and placed into a contemporary perspective. An appendix is included that provides a transcription with commentary of Peirce’s unpublished manuscript on modality from 1901.
David Lewis' modal counterpart theory falls prey to the famous Saul Kripke's objection, and this is mostly due to his 'static' ontology (divergence) of possibleworlds. This paper examines a genuinely realist but different, branching ontology of possibleworlds and a new definition of the counterpart relation, which attempts to provide us with a better account of de re modality, and to meet satisfactorily Kripke's claim, while being also ontologically more 'parsimonious'.
Accounts of modality in terms of fictional possibleworlds face an objection based on the idea that when modal claims are analysed in terms of fictions, the connection between analysans and analysandum seems artificial. Strong modal fictionalism, the theory according to which modal claims are analysed in terms of a fiction, has been defended by, among others, Seahwa Kim, who has recently claimed that the philosophical objection that the connection between modality and fictions is artificial can be met. (...) I propose a new way of spelling out the intuition of artificiality and show that strong modal fictionalism should be rejected. (shrink)
In the logic of theory change, the standard model is AGM, proposed by Alchourrón et al. (J Symb Log 50:510–530, 1985 ). This paper focuses on the extension of AGM that accounts for contractions of a theory by a set of sentences instead of only by a single sentence. Hansson (Theoria 55:114–132, 1989 ), Fuhrmann and Hansson (J Logic Lang Inf 3:39–74, 1994 ) generalized Partial Meet Contraction to the case of contractions by (possibly non-singleton) sets of sentences. In this (...) paper we present the possibleworlds semantics for partial meet multiple contractions. (shrink)
The issue of reduction of propositions to sets of possibleworlds is addressed. It is shown that, under some natural assumptions, there always exist recursive propositions, i.e. decidable sets of possibleworlds, which are not assigned to any sentence of a language. Some consequences of this result are discussed.
This chapter begins with a discussion of Kant's theory of judgment-forms. It argues that it is not true in Kant's logic that assertoric or apodeictic judgments imply problematic ones, in the manner in which necessity and truth imply possibility in even the weakest systems of modern modal logic. The chapter then discusses theories of judgment-form after Kant, the theory of quantification, Frege's Begriffsschrift, C. I. Lewis and the beginnings of modern modal logic, the proof-theoretic approach to modal logic, possible (...) world semantics, correspondence theory, and modality and quantification. (shrink)
Suppose the members of a group (e.g., committee, jury, expert panel) each form a judgment on which worlds in a given set are possible, subject to the constraint that at least one world is possible but not all are. The group seeks to aggregate these individual judgments into a collective judgment, subject to the same constraint. I show that no judgment aggregation rule can solve this problem in accordance with three conditions: “unanimity,” “independence” and “non-dictatorship,” Although the (...) result is a variant of an existing theorem on “group identification” (Kasher and Rubinstein, Logique et Analyse 160:385–395, 1997), the aggregation of judgments on which worlds are possible (or permissible, desirable, etc.) appears not to have been studied yet. The result challenges us to take a stance on which of its conditions to relax. (shrink)
There are ways in which the new tenseless theory of time is analogous to David Lewis’s modal realism. The new tenseless theory gives an indexical analysis of temporal terms such as ‘now’, while Lewis gives and indexical analysis of ‘actual’. For the new tenseless theory, all times are equally real; for Lewis, all worlds are equally real. In this paper I investigate this apparent analogy between these two theories, and ask whether a proponent of one is committed, by parity (...) of reasoning, to the other. I conclude that the analogy is merely apparent, and that independent reasons are needed to support each theory. (shrink)
In his early lecture note Versuch einiger Betrachtungen über den Optimismus (1759) a young supporter of metaphysical optimism called Immanuel Kant tested the Leibnizian optimism by posing some counter-arguments against it only to falsify them. His counter-arguments were very inventive and they feature often in modern scholarship on Leibniz. In this paper I will present Kant’s main arguments and evaluate them. I will argue that Kant’s understanding on Leibnizian optimism is little misguided and for this reason his own positive counter-argument (...) despite its ingeniousness is problematic. His second solution to the problem is comparable to the doctrine of metaphysical optimism, but fails also for the same reason as the first one. -/- . (shrink)
In the paper there is presented the semantic interpretation of idealism/ realism controversy which is one of the most essential issues in Ingarden’s phenomenological project of ontology. The procedure of semantic paraphrase which is contemporary developed by Wolen´ ski, is the main interpretative tool. In the central part of the paper, there is formulated the formal theory of the semantic framework underlying idealism/realism discourse. Finally, there are formulated some notes showing that intentional conception of negation may be used for defending (...) various idealistic positions. (shrink)
Leibniz argued that God would not create a world unless it was the best possible world. I defend Leibniz’s argument. I then consider whether God could refrain from creating if there were no best possible world. I argue that God, on pain of contradiction, could not refrain from creating in such a situation. I conclude that either this is the best possible world or God is not our creator.
"Jim would still be alive if he hadn't jumped" means that Jim's death was a consequence of his jumping. "x wouldn't be a triangle if it didn't have three sides" means that x's having a three sides is a consequence its being a triangle. Lewis takes the first sentence to mean that Jim is still alive in some alternative universe where he didn't jump, and he takes the second to mean that x is a non-triangle in every alternative universe where (...) it doesn't have three sides. Why did Lewis have such obviously wrong views? Because, like so many of his contemporaries, he failed to grasp the truth that it is the purpose of the present paper to demonstrate, to wit: No coherent doctrine assumes that statements about possibleworlds are anything other than statements about the dependence-relations governing our world. The negation of this proposition has a number of obviously false consequences, for example: all true propositions are necessarily true (there is no modal difference between "2+2=4" and "Socrates was bald"); all modal terms (e.g. "possible," "necessary") are infinitely ambiguous; there is no difference between laws of nature (e.g. "metal expands when heated") and accidental generalizations (e.g. "all of the coins in my pocket are quarters"); and there is no difference between the belief that 1+1=2 and the belief that arithmetic is incomplete. Given that possibleworlds are identical with mathematical models, it follows that the concept of model-theoretic entailment is useless in the way of understanding how inferences are drawn or how they should be drawn. Given that the concept of formal-entailment is equally useless in these respects, it follows that philosophers and mathematicians have simply failed to shed any light on the nature of the consequence-relation. Q's being either a formal or a model-theoretic consequence of P is parasitic on its bearing some third, still unidentified relation to P; and until this relation has been identified, the discipline of philosophical logic has yet to begin. (shrink)
The development of possibleworlds semantics for modal claims has led to a more general application of that theory as a complete semantics for various formal and natural languages, and this view is widely held to be an adequate (philosophical) interpretation of the model theory for such languages. We argue here that this view generates a self-referential inconsistency that indicates either the falsity or the incompleteness of PWS.
In this paper it is argued that the conjunction of linguistic ersatzism, the ontologically deflationary view that possibleworlds are maximal and consistent sets of sentences, and possible world semantics, the view that the meaning of a sentence is the set of possibleworlds at which it is true, implies that no actual speaker can effectively use virtually any language to successfully communicate information. This result is based on complexity issues that relate to our finite (...) computational ability to deal with large bodies of information and a strong, but well motivated, assumption about the cognitive accessibility of meanings of sentences ersatzers seem to be implicitly committed to. It follows that linguistic ersatzism, possible world semantics, or both must be rejected. (shrink)
If a possible-worlds semantic theory for modal logics is pure, then the assertion of the theory, taken at face-value, can bring no commitment to the existence of a plurality of possibleworlds (genuine or ersatz). But if we consider an applied theory (an application of the pure theory) in which the elements of the models are required to be possibleworlds, then assertion of such a theory, taken at face-value, does appear to bring commitment (...) to the existence of a plurality of possibleworlds. Or at least that is so if the applied theory is adequate. For an applied possible-worlds semantic theory that is constrained to contain only one-world models is bound to deliver results on validity, soundness and completeness that are apt to seem disastrous. I attempt to steer a course between commitment to the existence of a plurality of possibleworlds and commitment to such a disastrous applied possible-worlds semantics by noting, and developing, the position of one who asserts such a theory at face-value but who remains agnostic about the existence of other (non-actualized) possibleworlds. Thus, a novel interpretation of applied possible-worlds semantics is offered on which we may lay claim to whatever benefits such a theory offers while avoiding realism about (other) possibleworlds. Thereby, the contention that applied possible-worlds semantics gives us reason to be realists about possibleworlds is (further) undermined. (shrink)
It is difficult to wander far in contemporary metaphysics without bumping into talk of possibleworlds. And reference to possibleworlds is not confined to metaphysics. It can be found in contemporary epistemology and ethics, and has even made its way into linguistics and decision theory. What are those possibleworlds, the entities to which theorists in these disciplines all appeal? This paper sets out and evaluates a leading contemporary theory of possible (...) class='Hi'>worlds, David Lewis's Modal Realism. I note two competing ambitions for a theory of possibleworlds: that it be reductive and user-friendly. I then outline Modal Realism and consider objections to the effect that it cannot satisfy these ambitions. I conclude that there is some reason to believe that Modal Realism is not reductive and overwhelming reason to believe that it is not user-friendly. (shrink)
Possibleworlds, concrete or abstract as you like, are irrelevant to the truthmakers for modality—or so I shall argue in this paper. First, I present the neo-Humean picture of modality, and explain why those who accept it deny a common sense view of modality. Second, I present what I take to be the most pressing objection to the neo-Humean account, one that, I argue, applies equally well to any theory that grounds modality in possibleworlds. Third, (...) I present an alternative, properties-based theory of modality and explore several specific ways to flesh the general proposal out, including my favored version, the powers theory. And, fourth, I offer a powers semantics for counterfactuals that each version of the properties-based theory of modality can accept, mutatis mutandis. Together with a definition of possibility and necessity in terms of counterfactuals, the powers semantics of counterfactuals generates a semantics for modality that appeals to causal powers and not possibleworlds. (shrink)
It is difficult to wander far in contemporary metaphysics without bumping into talk of possibleworlds. And, reference to possibleworlds is not confined to metaphysics. It can be found in contemporary epistemology and ethics, and has even made its way into linguistics and decision theory. What are those possibleworlds, the entities to which theorists in these disciplines all appeal? Some have hoped that a theory of possibleworlds can be used (...) to reduce modality to non-modal terms. This paper sets reductive theories aside, and articulates and applies a framework for evaluating non-reductive theories of possibleworlds. I argue that, if we abjure reduction, we should aim for a theory of possibleworlds that is user-friendly. I then outline four leading contemporary theories and consider objections to each. My conclusions are negative: every theory we discuss fails to be user-friendly in some significant respect. (shrink)
... 112 ROBERT STALNAKER example Alvin Plantinga and Robert Adams) define possibleworlds in terms of states of affairs or propositions ; others (for example Max Cresswell) use a strategy quite similar to that of situation semantics, defining possibleworlds as constructs out of ..
Providing a possibleworlds semantics for a logic involves choosing a class of possibleworlds models, and setting up a truth definition connecting formulas of the logic with statements about these models. This scheme is so flexible that a danger arises: perhaps, any (reasonable) logic whatsoever can be modelled in this way. Thus, the enterprise would lose its essential tension. Fortunately, it may be shown that the so-called incompleteness-examples from modal logic resist possibleworlds (...) modelling, even in the above wider sense. More systematically, we investigate the interplay of truth definitions and model conditions, proving a preservation theorem characterizing those types of truth definition which generate the minimal modal logic. (shrink)
An outline for a modal interpretation in terms of possibleworlds is presented. The so-called Schmidt histories are taken to correspond to the physically possibleworlds. The decoherence function defined in the histories formulation of quantum theory is taken to prescribe a non-classical probability measure over the set of the possibleworlds. This is shown to yield dynamics in the form of transition probabilities for occurrent events in each world. The role of the consistency (...) condition is discussed. (shrink)
Dispositional essentialism, a plausible view about the natures of (sparse or natural) properties, yields a satisfying explanation of the nature of laws also. The resulting necessitarian conception of laws comes in a weaker version, which allows differences between possibleworlds as regards which laws hold in those worlds and a stronger version that does not. The main aim of this paper is to articulate what is involved in accepting the stronger version, most especially the consequence that all (...)possible properties exist in all worlds. I also suggest that there is no particularly strong reason for preferring the weaker to the stronger version. For example, Armstrong's instantiation condition on universals entails that according to strong necessitarianism every property is instantiated in all possibleworlds. But first we do not need to accept Armstrong's instantiation condition, in part because his arguments for it are forceful only for a contingentist about laws and properties. Secondly, even if we do accept the condition, the consequence that all properties are instantiated is not itself contradictory, so long as any form of necessitarianism holds. Strong necessitarianism is prima facie counter-intuitive. But for that matter so is weak necessitarianism. Accepting either weak or strong necessitarianism requires denying the force of intuition in this area. And indeed we have every reason to deny the force of intuition and its primary source, imagination, concerning modal facts. (shrink)
This book is a survey, fortified by original material, of metaphysical theories of modality set in terms of possibleworlds. Those theories include what Divers calls “genuine realism”, or “GR” — this is David Lewis’s “genuine modal realism” — and what Divers calls “actualist realism”, or “AR” — this seems to be the same as what Lewis called “ersatz modal realism”, which has also become widely know as “ersatzism”. Two important kinds of theory are not included: those that (...) treat modality by means not involving possibleworlds at all (for example, modalism, various kind of non-cognitivism, and Quinean eliminativism about modality); and those that, while treating modality by talking about possibleworlds, go on to deny that there are any possibleworlds in one way or another (for example, Rosen’s fictionalism, and Divers’ own agnosticism about possibleworlds). These get a short discussion towards the end of the introductory part of the book (sections 2.4–2.6), and Divers is planning to write a companion volume covering them. (shrink)
A possibleworlds treatment of the normal alethic modalities was, after classical model theory, logic’s most significant semantic achievement in the century just past. Kripke’s groundbreaking paper appeared in 1959 and, in the scant few succeeding years, its principal analytical tool, possibleworlds, was adapted to serve a range of quite different-seeming purposes – from nonnormal logics, to epistemic and doxastic logics, deontic and temporal logics and, not much later, the logic of counterfactual conditionals. In short (...) order, possibleworlds acquired a twofold reputation which has steadily enlarged to the present day. They were celebrated for both their mathematical power and their sheer versatility. This sets the stage for what I want to do here. I wish to explore the extent to which the supposed versatility of a possibleworlds semantics is justified. In so doing, I shall confine my attention to its role in (1) logics of counterfactual conditionals, and (2) logics of belief. The question I pose is, why and on what grounds should we think that the device of possibleworlds turns the semantic trick for these logics? My answer is that they do not turn the trick for them. Whereupon a further question presses for attention. If possibleworlds semantics don’t work there, why does virtually everyone think that they do? Answering this second question is risky. Who am I to say why virtually everyone thinks that the possibleworlds approach is more successful than I do? Who has vouchsafed me these powers? I shall try to mitigate the riskiness of my answer by contextualizing the evaluation of this approach in the following ways. First, the triumph of possibleworlds occurred in the midst of a powerful general trend in logical theory, especially, in the past 60 years. In that period, logical theory became aggressively and widely pluralistic. Second, the versatility – the sheer ubiquity – of possibleworlds as a tool of semantic and philosophical analysis, gives to possibleworlds a kind of hegemonic standing.. (shrink)
This thesis examines the alethic modal concepts of possibility and necessity. It is argued that one cannot do justice to all our modal talk without possibleworlds, i.e., complete ways that a cosmos might have been. I argue that not all of the proposed applications of possibleworlds succeed but enough remain to give one good theoretical reason to posit them. The two central problems now are: (1) What feature of reality makes correct alethic modal claims (...) true and (2) What are possibleworlds? (shrink)
The possible-worlds semantics for modality says that a sentence is possibly true if it is true in some possible world. Given classical prepositional logic, one can easily prove that every consistent set of propositions can be embedded in a ‘maximal consistent set’, which in a sense represents a possible world. However the construction depends on the fact that standard modal logics are finitary, and it seems false that an infinite collection of sets of sentences each finite (...) subset of which is intuitively ‘possible’ in natural language has the property that the whole set is possible. The argument of the paper is that the principles needed to shew that natural language possibility sentences involve quantification over worlds are analogous to those used in infinitary modal logic. (shrink)
Various writers have proposed that the notion of a possible world is a functional concept, yet very little has been done to develop that proposal. This paper explores a particular functionalist account of possibleworlds, according to which pluralities of possibleworlds are the bases for structures which provide occupants for the roles which analyse our ordinary modal concepts. It argues that the resulting position meets some of the stringent constraints which philosophers have placed upon (...) accounts of possibleworlds, while also trivializing the question what possibleworlds are. The paper then discusses a range of problems facing the functionalist position. (shrink)
The possible-worlds analysis of propositions identifies a proposition with the set of possibleworlds where it is true. This analysis has the hitherto unnoticed consequence that a proposition depends for its existence on the existence of every proposition that entails it. This peculiar consequence places the possible-worlds analysis in conflict with the conjunction of two compelling theses. One thesis is that a phrase of the form ‘the proposition that S’ is a rigid designator. The (...) other thesis is that a proposition which is directly about an object – a singular proposition – depends for its existence on the existence of the object. I defend these theses and conclude that the cost of the possible-worlds analysis is prohibitively high. (shrink)
Possible-worlds talk obscures the debate about haecceitism, rather than clarifying it. I distinguish haecceitism and anti-haeccatismfrom other doctrìnes which sometimes go under those names. Then defend the claim that any definition of 'haecceitism' using possible-worlds talk depends for its conectness on a substantive theory of the nature of possibleworlds. This explains why using possible-worlds talk when discussing haecceitism causes confusion: the term will mean different things to parties who depend on different (...) presuppositions about possibleworlds. (shrink)