Supervaluational accounts of vagueness have come under assault from Timothy Williamson for failing to provide either a sufficiently classical logic or a disquotational notion of truth, and from Crispin Wright and others for incorporating a notion of higher-order vagueness, via the determinacy operator, which leads to contradiction when combined with intuitively appealing ‘gap principles’. We argue that these criticisms of supervaluation theory depend on giving supertruth an unnecessarily central role in that theory as the sole notion of truth, rather than (...) as one mode of truth. Allowing for the co-existence of supertruth and local truth, we define a notion of local entailment in supervaluation theory, and show that the resulting logic is fully classical and allows for the truth of the gap principles. Finally, we argue that both supertruth and local truth are disquotational, when disquotational principles are properly understood. (shrink)

The first section (§1) of this essay defends reliance on truth values against those who, on nominalistic grounds, would uniformly substitute a truth predicate. I rehearse some practical, Carnapian advantages of working with truth values in logic. In the second section (§2), after introducing the key idea of auxiliary parameters (§2.1), I look at several cases in which logics involve, as part of their semantics, an extra auxiliary parameter to which truth is relativized, a parameter that caters to special kinds (...) of sentences. In many cases, this facility is said to produce truth values for sentences that on the face of it seem neither true nor false. Often enough, in this situation appeal is made to the method of supervaluations, which operate by “quantifying out” auxiliary parameters, and thereby produce something like a truth value. Logics of this kind exhibit striking differences. I first consider the role that Tarski gives to supervaluation in first order logic (§2.2), and then, after an interlude that asks whether neither-true-nor-false is itself a truth value (§2.3), I consider sentences with non-denoting terms (§2.4), vague sentences (§2.5), ambiguous sentences (§2.6), paradoxical sentences (§2.7), and future-tensed sentences in indeterministic tense logic (§2.8). I conclude my survey with a look at alethic modal logic considered as a cousin (§2.9), and finish with a few sentences of “advice to supervaluationists” (2.10), advice that is largely negative. The case for supervaluations as a road to truth is strong only when the auxiliary parameter that is “quantified out” is in fact irrelevant to the sentences of interest—as in Tarski’s definition of truth for classical logic. In all other cases, the best policy when reporting the results of supervaluation is to use only explicit phrases such as “settled true” or “determinately true,” never dropping the qualification. (shrink)

We present a theory VF of partial truth over Peano arithmetic and we prove that VF and ID 1 have the same arithmetical content. The semantics of VF is inspired by van Fraassen's notion of supervaluation.

This paper is concerned with the claim that supervaluationist consequence is not classical for a language including an operator for definiteness. Although there is some sense in which this claim is uncontroversial, there is a sense in which the claim must be qualified. In particular I defend Keefe's position according to which supervaluationism is classical except when the inference from phi to Dphi is involved. The paper provides a precise content to this claim showing that we might provide complete (and (...) sound) systems of deduction for supervaluationist consequence in which proofs are completely classical with the exception of a single last step (involving the above mentioned inference). (shrink)

Though it is standardly assumed that supervaluationism applied to vagueness is committed to global validity, Achille Varzi (2007) argues that the supervaluationist should take seriously the idea of adopting local validity instead. Varzi’s motivation for the adoption of local validity is largely based on two objections against the global notion: that it brings some counterexamples to classically valid rules of inference and that it is inconsistent with unrestricted higher-order vagueness. In this discussion I review these objections and point out ways (...) to address them not considered in Varzi’s paper. (shrink)

This paper discusses Fara's so-called 'Paradox of Higher-Order Vagueness' concerning supervaluationism. In the paper I argue that supervaluationism is not committed to global validity, as it is largely assumed in the literature, but to a weaker notion of logical consequence I call 'regional validity'. Then I show that the supervaluationist might solve Fara's paradox making use of this weaker notion of logical consequence. The paper is discussed by Delia Fara in the same volume.

It is often assumed that the supervaluationist theory of vagueness is committed to a global notion of logical consequence, in contrast with the local notion characteristic of modal logics. There are, at least, two problems related to the global notion of consequence. First, it brings some counterexamples to classically valid patterns of inference. Second, it is subject to an objection related to higher-order vagueness . This paper explores a third notion of logical consequence, and discusses its adequacy for the supervaluationist (...) theory. The paper proceeds in two steps. In the first step, the paper provides a deductive notion of consequence for global validity using the tableaux method. In the second step, the paper provides a notion of logical consequence which is an alternative to global validity, and discusses i) whether it is acceptable to the supervaluationist and ii) whether it plays a better role in a theory of vagueness in the face of the problems related to the global notion. (shrink)

The supervaluationist theory of vagueness is committed to a particular notion of logical consequence known as global validity. According to a recent objection, this notion of consequence is more problematic than is usually thought since i) it bears a commitment to some sort of bizarre inferences, ii) this commitment threatens the internal coherence of the theory and iii) we might find counterexamples to classically valid pat- terns of inference even in the absence of a definitely-operator (or similar device). As a (...) consequence, the supervaluationist theory itself is in trou- ble. This paper discusses the objection. (shrink)

A plausible thought about vagueness is that it involves a form of semantic incompleteness. To say that a predicate is vague is to say (at the very least) that its extension is incompletely specified. And where there is incomplete specification of extension there is indeterminacy—an indeterminacy between various ways that the specification of the predicate might be completed or, as some like to say, sharpened (or precisified). We shall argue that this idea is defective insofar as there are vague predicates (...) that cannot be sharpened. At least, there are predicates that are vague but that cannot be sharpened in such a way as to meet certain basic constraints that we think must be imposed on the very notion of a sharpening. (shrink)

This paper considers a generalisation of the sorites paradox, in which only topological notions are employed. We argue that by increasing the level of abstraction in this way, we see the sorites paradox in a new, more revealing light—a light that forces attention on cut-off points of vague predicates. The generalised sorites paradox presented here also gives rise to a new, more tractable definition of vagueness.

I consider two related objections to the claim that the law of excluded middle does not imply bivalence. One objection claims that the truth predicate captured by supervaluation semantics is not properly motivated. The second objection says that even if it is, LEM still implies bivalence. I show that LEM does not imply bivalence in a supervaluational language. I also argue that considering supertruth as truth can be reasonably motivated.

In this paper I criticize a version of supervaluation semantics. This version is called "Region-Valuation" semantics. It's developed by Pablo Cobreros. I argue that all supervaluationists, regionalists in particular, and truth-value gap theorists of vagueness more generally, are commited to the validity of D-intro, the principle that every sentence entails its definitization (the truth of "Paul is tall" guarantees the truth of "Paul is definitely tall"). The principle embroils one in a paradox that's distinct from, but related to, the sorites (...) paradox. I call it the "gap-principles paradox". -/- . (shrink)

This paper examines the mind and language of an omniscient being from a supervaluationist perspective. Two questions hall receive special attention. How ought the supervaluationist explicate the concept of omniscience? And what ought the supervaluationist expect an omniscient speaker to say about a Sorites series?

Read as a comment on Crispin Wright's \"Vagueness: A Fifth Column Approach\", this paper defends a form of supervaluationism against Wright's criticisms. Along the way, however, it takes up the question what is really wrong with Epistemicism, how the appeal of the Sorities ought properly to be understood, and why Contextualist accounts of vagueness won't do.

Vagueness is an extremely widespread feature of language, famously associated with the sorites paradox. One instance of this paradox concludes that a single grain of sand is a heap of sand, by starting with a large heap of sand and invoking the plausible premise that if you take one grain of sand away from a heap of sand, then you still have a heap. The supervaluationist theory of vagueness states that a sentence is true if and only if it is (...) true on all ways of making it precise. This yields borderline case predications that are neither true nor false, but yet classical logic is preserved almost entirely. The sorites paradox is solved because the main premise comes out false – on each way of making 'heap' precise, there is some first grain that turns a heap into a non-heap – but there is no sharp boundary to 'heap' because it is a different grain on different ways of making 'heap' precise; so, there is no grain of which it is true to say it is that first grain. The theory has a range of merits in comparison with rival theories, such as the epistemic view or degree theories of vagueness. Objections have been made (and answers offered) in relation to its treatment of higher-order vagueness and what it says about truth and validity. Author Recommends Fine, Kit. 'Vagueness, Truth and Logic.' Synthese 30 (1975). 265–300. Reprinted in Keefe and Smith 1997. This is the classic text introducing supervaluationism as a treatment of vagueness. It provides both philosophical discussion and formal modelling, demonstrating the adherence to classical logic that the theory yields. Keefe, Rosanna and Peter Smith, eds. Vagueness: A Reader . Cambridge, MA: MIT Press. This collection includes many classic papers on vagueness, including Fine's paper, cited above, a paper by Dummett that offers (but rejects) a precursor of the supervaluationist view, another less well-known early presentation of the view by Henyrk Mehlberg and discussion and defences of the main rival theories of vagueness. Keefe, Rosanna. Theories of Vagueness . Cambridge: Cambridge University Press, 2000. This book defends a supervaluationist theory of vagueness. It discusses the phenomena of vagueness and what is required of a theory of vagueness, before considering and rejecting the major alternatives in turn. Williamson, Timothy. Vagueness . London: Routledge, 1994. This book defends the epistemic theory of vagueness, which maintains that vague predicates do have sharp boundaries, we just do not know where those boundaries lie. It also contains detailed discussions of opposing theories, including supervaluationism. Unger, Peter. 'The Problem of the Many.' Midwest Studies in Philosophy 5 (1980). Eds. P.A. French, T.E. Uehling Jr and H.K. Wettstein. Minneapolis, MN: University of Minnesota Press. This is the classic presentation of the Problem of the Many, to which a supervaluationist solution is relatively popular. This problem arises because frequently the boundaries of an object – say a cloud – are not sharply delineated. Each of the many ways of drawing the boundary seems to be an object of the type in question – say a cloud – hence the problem that there are many things when there should be just one. The supervaluationist, it seems, can say that there is just one cloud because that is true on each precisification. Williams, J. Robert G. 'An Argument for the Many.' Proceedings of the Aristotelian Society 106 (2006). 409–17. Detailed discussion of Unger's Problem of the Many, especially in relation to the supervaluationist solution. Shapiro, Stewart. Vagueness in Context . Oxford: Oxford University Press, 2006. In this book, Shapiro employs a supervaluationist framework, without endorsing some of the central claims of the standard supervaluationist theory of vagueness. Online Materials http://plato.stanford.edu/entries/vagueness/ http://plato.stanford.edu/entries/sorites-paradox/ http://plato.stanford.edu/entries/problem-of-many/ http://www.st-andrews.ac.uk/~arche/projects/vagueness/bibliography.shtml Sample Syllabus Week I: Introduction to Vagueness Keefe, Theories of Vagueness (especially chapters 1 and 2) Williamson, Vagueness (especially chapters 1 and 2) Week II: Supervaluationist Theory: logic and semantics Keefe, 'Vagueness: Supervaluationism.' Philosophy Compass 3.2 (2008): 315–24, 10.1111/j.1747-9991.2008.00124.x Fine, 'Vagueness, Truth and Logic' Keefe, Theories of Vagueness (especially chapter 7) Week III: Higher Order Vagueness and the D Operator Keefe, Theories of Vagueness (especially chapter 8) Fara, Delia Graff. 'Gap Principles, Penumbral Consequence and Infinitely Higher-Order Vagueness.' Liars and Heaps . Ed. J.C. Beall. Oxford: Oxford University Press, 2003. 195–221. Originally published under the name 'Delia Graff'. Week IV: Truth and Validity Keefe, Theories of Vagueness (especially chapter 8) Keefe, 'Supervaluationism and Validity.' Philosophical Topics 28 (2000). 93–105. Cobreros, 'Supervaluations and Logical Consequence: Retrieving the Local Perspective.' Studia Logica , Special Issue on Vagueness , 2009 Week V: Problem of the Many Unger, "The Problem of the Many" Williams, "An Argument for the Many" Week VI: Rival Theories Williamson, Vagueness (especially chapters 7 and 8) Keefe and Smith, Vagueness: A Reader (e.g. chapters 11, 14–6) Focus Questions 1 How important is it for a theory of vagueness to accommodate penumbral connections? Are there any putative penumbral connections that the supervaluationist cannot accommodate? 2 According to supervaluationism, what does it take for "Katie said that Hannah is tall" to be true? Does the view have implausible consequences for indirect speech reports when vague terms are used? 3 Is higher-order vagueness a problem for supervaluationism? 4 Is there more than one viable option for the account of validity in a supervaluationist framework? 5 Can a supervaluationist account of vagueness accommodate the full extent of context dependence exhibited in the use of vague predicates? (shrink)

Most expressions in natural language are vague. But what is the best semantic treatment of terms like 'heap', 'red' and 'child'? And what is the logic of arguments involving this kind of vague expression? These questions are receiving increasing philosophical attention, and in this timely book Rosanna Keefe explores the questions of what we should want from an account of vagueness and how we should assess rival theories. Her discussion ranges widely and comprehensively over the main theories of vagueness and (...) their supporting arguments, and she offers a powerful and original defence of a form of supervaluationism, a theory that requires almost no deviation from standard logic yet can accommodate the lack of sharp boundaries to vague predicates and deal with the paradoxes of vagueness in a methodologically satisfying way. Her study will be of particular interest to readers in philosophy of language and of mind, philosophical logic, epistemology and metaphysics. (shrink)

Michael Kremer defines fixed-point logics of truth based on Saul Kripke’s fixed point semantics for languages expressing their own truth concepts. Kremer axiomatizes the strong Kleene fixed-point logic of truth and the weak Kleene fixed-point logic of truth, but leaves the axiomatizability question open for the supervaluation fixed-point logic of truth and its variants. We show that the principal supervaluation fixed point logic of truth, when thought of as consequence relation, is highly complex: it is not even analytic. We also (...) consider variants, engendered by a stronger notion of ‘fixed point’, and by variant supervaluation schemes. A ‘logic’ is often thought of, not as a consequence relation, but as a set of sentences – the sentences true on each interpretation. We axiomatize the supervaluation fixed-point logics so conceived. (shrink)

Timothy Williamson famously offered an argument from these Tarskian principles in favor of bivalence. I show, dwelling on (Andjelkovic & Williamson, 2000), that the argument depends on a contentious formulation of the Tarskian principles about truth (and falsity), which the supervaluationist can reject without jeopardizing the Tarskian insight. In the mentioned paper, Adjelkovic and Williamson argue that, even if the appropriate formulation seems to make room for failure of bivalence in borderline cases, this appearance is illusory, once one grants an (...) independent further principle involving biconditionals. I finally argue that the formulation of this is, however, contentious in a similar manner. (shrink)

Donald Smith (2006) argues that if ‘I’ is indeed vague, and the view of vagueness as semantic indecision correct after all, then ‘I’ cannot refer to a composite material object. But his considerations would, if sound, also establish that ‘Tibbles,’ ‘Everest,’ or ‘Toronto,’ do not refer to composite material objects either—nor hence, presumably, to cats, mountains, or cities. And they can be resisted, anyway. Or so I argue.

One winter’s Saturday Clarence wakes up. He realises he has left his umbrella at work. The office is locked, and he can’t get in. Being one of those people who punish themselves for their mistakes, he can’t bring himself to buy a replacement. He has an engagement six kilometres down the road and starts wondering whether it will rain. Normally, this would not be a problem, but his motor vehicle has broken down because he forgot to have it serviced. And (...) of course, he blames himself for this mistake, so it is only natural that he can’t bring himself to hire a cab or take a bus. He really should hope that it rains and that he gets drenched on the way to his engagement, but he is only human after all, and a small part of himhopes that it is a sunny day. (shrink)

Supervaluational treatments of vagueness are currently quite popular among those who regard vagueness as a thoroughly semantic phenomenon. Peter Unger's 'problem of the many' may be regarded as arising from the vagueness of our ordinary physical-object terms, so it is not surprising that supervaluational solutions to Unger's problem have been offered. I argue that supervaluations do not afford an adequate solution to the problem of the many. Moreover, the considerations I raise against the supervaluational solution tell also against the solution (...) to the problem of the many which is suggested by adherents of the epistemic theory of vagueness. (shrink)

Among other good things, supervaluation is supposed to allow vague sentences to go without truth values. But Jerry Fodor and Ernest Lepore have recently argued that it cannot allow this - not if it also respects certain conceptual truths. The main point I wish to make here is that they are mistaken. Supervaluation can leave truth-value gaps while respecting the conceptual truths they have in mind.

Vagueness manifests itself (among other things) in our inability to find boundaries to the extension of vague predicates. A semantic theory of vagueness plans to justify this inability in terms of the vague semantic rules governing language and thought. According to a supporter of semantic theory, the inability to find such a boundary is not dependent on epistemic limits and an omniscient being like God would be equally unable. Williamson (Vagueness, 1994 ) argued that cooperative omniscient beings adequately instructed would (...) find a precise boundary in a sorites series and that, for this reason, the semantic theory misses its target, while Hawthorne (Philosophical Studies 122:1–25, 2005 ) stood with the semantic theorists and argued that the linguistic behaviour of a cooperative omniscient being like God would clearly demonstrate that he does not find a precise boundary in the sorites series. I argue that Hawthorne’s definition of God’s cooperative behaviour cannot be accepted and that, contrary to what has been assumed by both Williamson and Hawthorne, an omniscient being like God cannot be a cooperative evaluator of a semantic theory of vagueness. (shrink)

Timothy Williamson, in various places, has put forward an argument that is supposed to show that denying bivalence is absurd. This paper is an examination of the logical force of this argument, which is found wanting.

Supervaluational theories of vagueness have achieved considerable popularity in the past decades, as seen in eg [5], [12]. This popularity is only natural; supervaluations let us retain much of the power and simplicity of classical logic, while avoiding the commitment to strict bivalence that strikes many as implausible. Like many nonclassical logics, the supervaluationist system SP has a natural dual, the subvaluationist system SB, explored in eg [6], [28].1 As is usual for such dual systems, the classical features of SP (...) (typically viewed as benefits) appear in SB in ‘mirror-image’ form, and the nonclassical features of SP (typically viewed as costs) also appear in SB in ‘mirror-image’ form. Given this circumstance, it can be difficult to decide which of two dual systems is better suited for an approach to vagueness.2 The present paper starts from a consideration of these two approaches— the supervaluational and the subvaluational—and argues that neither of them is well-positioned to give a sensible logic for vague language. §2 presents the systems SP and SB and argues against their usefulness. Even if we suppose that the general picture of vague language they are often taken to embody is accurate, we ought not arrive at systems like SP and SB. Instead, such a picture should lead us to truth-functional systems like strong Kleene logic (K3) or its dual LP. §3 presents these systems, and argues that supervaluationist and subvaluationist understandings of language are better captured there; in particular, that a dialetheic approach to vagueness based on the logic LP is a more sensible approach. §4 goes on to consider the phenomenon of higher-order vagueness within an LP-based approach, and §5 closes with a consideration of the sorites argument itself. (shrink)

A semantics of vagueness should reject the principle that every statement has a truth-value yet retain the classical tautologies. A many-value, non-truth-functional semantics and a semantics of super-valuations each have this result. According to the super-valuation approach, 'if a man with n hairs on his head is bald, then a man with n plus one hairs on his head is also bald' is false because it comes out false no matter how the vague predicate 'is bald' is appropriately made precise. (...) But why should a sentence in which components actually remain imprecise be regarded as actually false just because it would be false if its components were precise? On one of the alternative treatments of quantification allowed by the many-value approach, the sentence in question is assigned an intermediate value closer to 'false' than to 'true'. Despite the elegance of the super-valuation approach, there are reasons to prefer the many-value approach. (shrink)

A standard response to the problem of diachronic vagueness is ‘the semantic solution’, which demands an abundant ontology. Although it is known that the abundant ontology does not logically preclude endurantism, their combination is rejected because it necessitates massive coincidence between countless objects. In this paper, I establish that the semantic solution is available not only to perdurantists but also to endurantists by showing that there is no problem with such ubiquitous and principled coincidence.

Since its first appearance in 1966, the notion of a supervaluation has been regarded by many as a powerful tool for dealing with semantic gaps. Only recently, however, applications to semantic gluts have also been considered. In previous work I proposed a general framework exploiting the intrinsic gap/glut duality. Here I also examine an alternative account where gaps and gluts are treated on a par: although they reflect opposite situations, the semantic upshot is the same in both cases--the value of (...) some expressions is not uniquely defined. Other strategies for generalizing supervaluations are considered and some comparative facts are discussed. (shrink)

If we adopt a supervaluational semantics for vagueness, what sort of logic results? As it turns out, the answer depends crucially on how the standard notion of validity as truth preservation is recast. There are several ways of doing this within a supervaluational framework, the main alternative being between 'global' construals (e.g. an argument is valid if and only if it preserves truth-under-all-precisifications) and 'local' construals (an argument is valid if and only if, under all precisifications, it preserves truth). The (...) former alternative is by far more popular, but I argue in favour of the latter, for (i) it does not suffer from a number of serious objections, and (ii) it makes it possible to restore global validity as a defined notion. (shrink)

Most event-referring expressions are vague: it is utterly difficult, if not impossible, to specify the exact spatiotemporal location of an event from the words that we use to refer to it. We argue that in spite of certain prima facie obstacles, such vagueness can be given a purely semantic (broadly supervaluational) account.

A plausible thought about vagueness is that it involves semantic incompleteness. To say that a predicate is vague is to say (at the very least) that its extension is incompletely specified. Where there is incomplete specification of extension there is indeterminacy, an indeterminacy between various ways in which the specification of the predicate might be completed or sharpened. In this paper we show that this idea is bound to founder by presenting an argument to the effect that there are vague (...) predicates which cannot be sharpened in such a way as to meet certain basic constraints (of penumbral connection and public accessibility) that must be imposed on the very notion of a sharpening. (shrink)

What the world needs now is another theory of vagueness. Not because the old theories are useless. Quite the contrary, the old theories provide many of the materials we need to construct the truest theory of vagueness ever seen. The theory shall be similar in motivation to supervaluationism, but more akin to many-valued theories in conceptualisation. What I take from the many-valued theories is the idea that some sentences can be truer than others. But I say very different things to (...) the ordering over sentences this relation generates. I say it is not a linear ordering, so it cannot be represented by the real numbers. I also argue that since there is higher-order vagueness, any mapping between sentences and mathematical objects is bound to be inappropriate. This is no cause for regret; we can say all we want to say by using the comparative truer than without mapping it onto some mathematical objects. From supervaluationism I take the idea that we can keep classical logic without keeping the familiar bivalent semantics for classical logic. But my preservation of classical logic is more comprehensive than is normally permitted by supervaluationism, for I preserve classical inference rules as well as classical sequents. And I do this without relying on the concept of acceptable precisifications as an unexplained explainer. The world does not need another guide to varieties of theories of vagueness, especially since Timothy Williamson (1994) and Rosanna Keefe (2000) have already provided quite good guides. I assume throughout familiarity with popular theories of vagueness. (shrink)

Recently four different papers have suggested that the supervaluational solution to the Problem of the Many is flawed. Stephen Schiffer (1998, 2000a, 2000b) has argued that the theory cannot account for reports of speech involving vague singular terms. Vann McGee and Brian McLaughlin (2000) say that theory cannot, yet, account for vague singular beliefs. Neil McKinnon (2002) has argued that we cannot provide a plausible theory of when precisifications are acceptable, which the supervaluational theory needs. And Roy Sorensen (2000) argues (...) that supervaluationism is inconsistent with a directly referential theory of names. McGee and McLaughlin see the problem they raise as a cause for further research, but the other authors all take the problems they raise to provide sufficient reasons to jettison supervaluationism. I will argue that none of these problems provide such a reason, though the arguments are valuable critiques. In many cases, we must make some adjustments to the supervaluational theory to meet the posed challenges. The goal of this paper is to make those adjustments, and meet the challenges. (shrink)

It is widely assumed that the methods and results of science have no place among the data to which our semantics of vague predicates must answer. This despite the fact that it is well known that such prototypical vague predicates as ‘is bald’ play a central role in scientific research (e.g. the research that established Rogaine as a treatment for baldness). I argue here that the assumption is false and costly: in particular, I argue one cannot accept either supervaluationist semantics, (...) or the criticism of that semantics offered by Fodor and Lepore, without having to abandon accepted, and unexceptionable, scientific methodology. (shrink)

Supervaluationism is often described as the most popular semantic treatment of indeterminacy. There’s little consensus, however, about how to fill out the barebones idea to include a characterization of logical consequence. In a recent paper, Achille Varzi writes: it is pretty clear that there is not just one supervaluational semantics out there–there are lots of such semantics; and although it is true that they all exploit the same insight, their relative differences are by no means immaterial . . . a (...) lot depends on how a given supervaluationally machinery is brought into play when it comes to explaining the logic of the language. (Varzi, forthcoming, p.463) The ‘supervaluational machinery’ to be discussed here is the idea of a supervaluational model defined below. Varzi highlights the fact that that all sorts of properties of sequents that are candidates for the name ‘validity’ can be defined using the resources of supervaluational models. (shrink)

This paper explores the interaction of well-motivated (if controversial) principles governing the probability conditionals, with accounts of what it is for a sentence to be indefinite. The conclusion can be played in a variety of ways. It could be regarded as a new reason to be suspicious of the intuitive data about the probability of conditionals; or, holding fixed the data, it could be used to give traction on the philosophical analysis of a contentious notion—indefiniteness. The paper outlines the various (...) options, and shows that ‘rejectionist’ theories of indefiniteness are incompatible with the results. Rejectionist theories include popular accounts such as supervaluationism, non-classical truth-value gap theories, and accounts of indeterminacy that centre on rejecting the law of excluded middle. An appendix compares the results obtained here with the ‘impossibility’ results descending from Lewis ( 1976 ). (shrink)

In the literature on supervaluationism, a central source of concern has been the acceptability, or otherwise, of its alleged logical revisionism. I attack the presupposition of this debate: arguing that when properly construed, there is no sense in which supervaluational consequence is revisionary. I provide new considerations supporting the claim that the supervaluational consequence should be characterized in a ‘global’ way. But pace Williamson 1994) and Keefe (2000), I argue that supervaluationism does not give rise to counterexamples to familiar inference-patterns (...) such as reductio and conditional proof. (shrink)

If one believes that vagueness is an exclusively representational phenomenon, one faces the problem of the many. In the vicinity of Kilimanjaro, there are many many ‘mountain candidates’ all, apparently, with more-or-less equal claim to be mountains. David Lewis has defended a radical claim: that all the billions of mountain candidates are mountains. This paper argues that the supervaluationist about vagueness should adopt Lewis’ proposal, on pain of losing their best explanation of the seductiveness of the sorites.