The present PhD dissertation aims to examine the relation between modality and change in Aristotle’s metaphysics. -/- On the one hand, Aristotle supports his modal realism (i.e., worldly objects have modal properties - potentialities and essences - that ground the ascriptions of possibility and necessity) by arguing that the rejection of modal realism makes change inexplicable, or, worse, banishes it from the realm of reality. On the other hand, the Stagirite analyses processes by means of modal notions (‘change is the (...) actuality of what is virtual insofar as it is virtual’). In other words: to grasp what change is, one has to resort to the modal idiom of potentialities, while the fact that there is change is indicative of the fact that nature is full of modal properties. -/- Aristotle’s modal and kinetic realism finds a negative in the figure of the Megaric Diodorus Kronus. The polemical situation of Greek philosophy has indeed the dialectical advantage of not opposing the Aristotelian position to a sui generis straw man. Both in its reduction of modal judgements to temporal quantifications and in its dissolution of the reality of the state-of-being-in-motion in favour of a cinematographic view of processes, the philosophical figure of reductionist antirealism embodied by Diodorus constitutes an alternative that takes the opposite view of Aristotle’s realism. -/- The present study is structured as a discussion between these two positions. In the face of Diodorus’ antirealist challenges, Aristotle articulates modal and kinetic considerations: the answers he gives to Diodorus’ puzzles thus provide valuable insight into his metaphysics. Moreover, the examination of Aristotle’s and Diodorus’ metaphysics, because of their insight and originality, will not fail to interest the philosopher concerned with the metaphysical foundations of modern physics, insofar as the entanglement between modalities and processes is nowadays at the core of mechanics (phase spaces, path integrals, etc.). (shrink)

The view that contradictions cannot be true has been part of accepted philosophical theory since at least the time of Aristotle. In this regard, it is almost unique in the history of philosophy. Only in the last forty years has the view been systematically challenged with the advent of dialetheism. Since Graham Priest introduced dialetheism as a solution to certain self-referential paradoxes, the possibility of true contradictions has been a live issue in the philosophy of logic. Yet, despite the arguments (...) advanced by dialetheists, many logicians and philosophers still hold the opinion that contradictions cannot be true. -/- Rather than advocating the truth of certain contradictions, this thesis offers a different challenge to the classical logician. By showing that it can be philosophically coherent to propose that true contradictions are metaphysically possible, the thesis suggests that the classical logician must do more than she currently has to justify her confidence in the impossibility of true contradictions. Simply fighting off the dialetheist’s putative examples of true contradictions at the actual world isn’t enough to justify the classical logician’s conclusion that true contradictions are impossible. -/- To aid the thesis dialectically, we introduce a new position, absolutism, which hypothesises that it’s metaphysically possible for at least one contradiction to be true, contrasting with the dialetheic hypothesis that some contradictions are true in the actual world. We demonstrate that absolutism can be given a philosophically coherent interpretation, an appropriate logic, and that certain criticisms are completely toothless against absolutism. The challenge put to the classical logician is then: On what logical or philosophical grounds can we rule out the metaphysical possibility of true contradictions? (shrink)

This extended abstract summarises some of the basic points of AI ethics and policy as they present themselves now. We explain the notion of AI, the main ethical issues in AI and the main policy aims and means.

What is the relation of logic to thinking? My dissertation offers a new argument for the claim that logic is constitutive of thinking in the following sense: representational activity counts as thinking only if it manifests sensitivity to logical rules. In short, thinking has to be minimally logical. An account of thinking has to allow for our freedom to question or revise our commitments – even seemingly obvious conceptual connections – without loss of understanding. This freedom, I argue, requires that (...) thinkers have general abilities to respond to support and tension among their thoughts. And these abilities are constituted by following logical rules. So thinkers have to follow logical rules. But there isn’t just one correct logic for thinking. I show that my view is consistent with logical pluralism: there are a range of correct logics, any one of which a thinker might follow. A logic for thinking does, however, have to contain certain minimal principles: Modus Ponens and Non-Contradiction, and perhaps others. We follow logical rules by exercising logical capacities, which display a distinctive first-person/third-person asymmetry: a subject can find the instances of a rule compelling without seeing them as instances of a rule. As a result, there are two limits on illogical thinking. First, thinkers have to tend to find instances of logical rules compelling. Second, thinkers can’t think in obviously illogical ways. So thinking has to be logical – but not perfectly so. When we try to think, but fail, we produce nonsense. But our failures to think are often subjectively indistinguishable from thinking. To explain how this occurs, I offer an account of nonsense. To be under the illusion that some nonsense makes sense is to enter a pretence that the nonsense is meaningful. Our use of nonsense within the pretence relies on the role of logical form in understanding. Finally, while the normativity of logic doesn’t fall directly out of logical constitutivism, it’s possible to build an attractive account of logical normativity which has logical constitutivism as an integral part. I argue that thinking is necessary for human flourishing, and that this is the source of logical normativity. (shrink)

In this paper, I argue against what I call “natural realism” about social kinds, the view according to which social categories have natural boundaries, independent of our thought. First, I draw a distinction between two different types of entity realism, one being about the existence of the entity, “ontological realism”, and the other one being about the direct mind-independence of the entity, “natural realism”. After endorsing ontological realism, I present the natural realist argument according to which there would be certain (...) social kinds, such as economic recessions and racism, even if we had no clue about their existence and nature. I claim that the argument fails insofar it mistakes the single instances for the kinds themselves. I then argue against natural realism by showing how the vagueness characterizing the boundaries of social kinds puts the realist in front of a dilemma: either she accepts the vagueness of these boundaries as ontic, a metaphysically problematic thesis, or she accepts that most or all social kinds remain unknown, an epistemologically problematic thesis. Thus, I argue that antirealism, according to which social kinds are constructed, is a better alternative to the realist account. (shrink)

Beach's Gaelic Symphony is plausibly an abstract object that Beach created. The view that people create some abstract objects is called abstract creationism. There are abstract creationists about many kinds of objects, including musical works, fictional characters, arguments, words, internet memes, installation artworks, bitcoins, and restaurants. Alternative theories include materialism and Platonism. This paper discusses some of the most serious objections against abstract creationism. Arguably, these objections have ramifications for questions in metaphysics pertaining to the abstract/concrete distinction, time, causation, vague (...) existence, vague identity, and inadvertent creation. (shrink)

We implement a recent characterization of metaphysical indeterminacy in the context of orthodox quantum theory, developing the syntax and semantics of two propositional logics equipped with determinacy and indeterminacy operators. These logics, which extend a novel semantics for standard quantum logic that accounts for Hilbert spaces with superselection sectors, preserve different desirable features of quantum logic and logics of indeterminacy. In addition to comparing the relative advantages of the two, we also explain how each logic answers Williamson’s challenge to any (...) substantive account of determinacy: For any proposition p, what could the difference between “p” and “it’s determinate that p” ever amount to? (shrink)

I explore the possibility of a structuralist interpretation of homotopy type theory (HoTT) as a foundation for mathematics. There are two main aspects to HoTT's structuralist credentials. First, it builds on categorical set theory (CST), of which the best-known variant is Lawvere's ETCS. I argue that CST has merit as a structuralist foundation, in that it ascribes only structural properties to typical mathematical objects. However, I also argue that this success depends on the adoption of a strict typing system which (...) undermines the metaphysical seriousness of this structuralism. Homotopy type theory adds to CST a distinctive theory of identity between sets, which arguably allows its objects to be seen as ante rem structures. I examine the prospects for such a view, and address many other interpretive problems as they arise. (shrink)

It has been argued that non-relativistic quantum mechanics is the best hunting ground for genuine examples of metaphysical indeterminacy. Approaches to metaphysical indeterminacy can be divided into two families: meta-level and object-level accounts. It has been shown :27–245, 2010. https://doi.org/10.1080/00048400903097786; Skow in Philosophical Quarterly 60:851–858, 2010) that the most popular version of the meta-level accounts, namely the metaphysical supervaluationism proposed by Barnes and Williams, fails to deal with quantum indeterminacy. Such a fact has been taken by many as a challenge (...) to adapt supervaluationism to quantum cases. In this paper, I will focus on the very last of these attempts, i.e. the situation semantics account proposed by Darby and Pickup. After having shown where quantum indeterminacy arises and having surveyed the assumptions endorsed by the participants of the debate, I turn to Darby and Pickup’s proposal. I argue that, despite the machinery introduced, their account still fails to account for quantum indeterminacy. After considering some possible counterarguments, I suggest in the conclusion that one can plausibly extend the argument to those meta-level approaches that treat quantum indeterminacy as worldly indecision. (shrink)

In this paper, I assess the analysis of vagueness of objects in terms of the theory of constitution with respect to the notion of vague identity. Some proponents of the constitution theory see it as an advantage of their account that analysing the spatial and temporal vagueness of objects in terms of the relation of vague constitution avoids commitment to vague identity, which is seen as a controversial notion. I argue that even though the constitution theory may plausibly be applied (...) to the phenomenon of vague boundaries, it fails to account fully for other cases of spatial and temporal vagueness. There are what I call ‘mid-extension’ vagueness cases, in which the tools of the constitution theory applied in the analysis of boundary vagueness are insufficient to avoid commitment to vague identity. (shrink)

Many philosophers think that common sense knowledge survives sophisticated philosophical proofs against it. Recently, however, Bryan Frances (forthcoming) has advanced a philosophical proof that he thinks common sense can’t survive. Exploiting philosophical paradoxes like the Sorites, Frances attempts to show how common sense leads to paradox and therefore that common sense methodology is unstable. In this paper, we show how Frances’s proof fails and then present Frances with a dilemma.

Provisional draft, pre-production copy of my book “The Modal Future” (forthcoming with Cambridge University Press).

My paper characterizes religious beliefs in terms of vagueness. I introduce my topic by providing a general overview of my main claims. In the subsequent section, I develop basic distinctions and terminology for handling the notion of religious tradition and capturing vagueness. In the following sections, I make the case for my claim that religious beliefs are vague by developing a general argument from the interconnection between the referential opacity of religious belief content and the long-term communitarian history of the (...) precisification of what such content means. I start from describing an empirical example in the third section, and then I move to settle the matter in a conceptually argumentative frame in the fourth one. My conclusions in the final section address a few of consequences relevant to debates about religious epistemology and religious diversity. (shrink)

This paper presents and defends an argument that the continuum hypothesis is false, based on considerations about objective chance and an old theorem due to Banach and Kuratowski. More specifically, I argue that the probabilistic inductive methods standardly used in science presuppose that every proposition about the outcome of a chancy process has a certain chance between 0 and 1. I also argue in favour of the standard view that chances are countably additive. Since it is possible to randomly pick (...) out a point on a continuum, for instance using a roulette wheel or by flipping a countable infinity of fair coins, it follows, given the axioms of ZFC, that there are many different cardinalities between countable infinity and the cardinality of the continuum. (shrink)

In this dissertation, I argue that vagueness is a metaphysical phenomenon---that properties and objects can be vague---and propose a trivalent theory of vagueness meant to account for the vagueness in the world. In the first half, I argue against the theories that preserve classical logic. These theories include epistemicism, contextualism, and semantic nihilism. My objections to these theories are independent of considerations of the possibility that vagueness is a metaphysical phenomenon. However, I also argue that these theories are not capable (...) of accommodating metaphysical vagueness. As I move into my positive theory, I first argue for the possibility of metaphysical vagueness and respond to objections that charge that the world cannot be vague. One of these objections is Gareth Evans' much-disputed argument that vague identities are impossible. I then describe what I call the logic of states of affairs. The logic of states of affairs has as its atomic elements states of affairs that can obtain, unobtain, or be indeterminate. Finally, I argue that the logic of states of affairs is a better choice for a theory of vagueness than other logics that could accommodate metaphysical vagueness such as supervaluationism and degree theories. Preference should be given to the logic of states of affairs because it provides a better explanation of higher-order vagueness and does a better job of matching our ordinary understandings of logical operators than supervaluationism does and because it provides a more general account of indeterminacy than the account given by degree theories. Advisor: Reina Hayaki. (shrink)

A world where there exists n concrete things is a count-determinate world. The orthodox view is count-determinacy is necessary; if to be is to be the value of a variable and the domain of quantification is enumerable, count-determinacy follows. Yet I argue how many there are can be indeterminate; count-indeterminacy is metaphysically possible and even likely actual. Notably, my argument includes rebuttals of Evans’ reductio of indeterminate identity and the Lewis/Sider ‘argument from vagueness’. Count-indeterminacy should therefore be recognized as another (...) basic form of genuine metaphysical indeterminacy, in addition to types recently defend by Barnes, Williams, and Wilson. (shrink)

A number of analytical philosophers have recently endorsed the view that the world itself is indeterminate in some respect. Intriguingly, ideas similar to the view are expressed by thinkers from Chinese Madhyamaka Buddhism, which may shed light on the current discussion of worldly indeterminacy. Using as a basis Chinese Madhyamaka thought, together with Jessica Wilson’s account of indeterminacy, I develop an ontological conception of indeterminacy, termed ontic indeterminacy, which centres on two complementary ideas—conclusive indeterminability and provisional determinability. I show that (...) OI is well-equipped to tackle several issues of worldly indeterminacy. My overarching aim is to present a viable and sustainable perspective on the subject of indeterminacy to enrich analytical philosophers’ insights into the intricate nature of reality. (shrink)

ABSTRACT Many phenomena appear to be indeterminate, including material macro-object boundaries and certain open future claims. Here I provide an account of indeterminacy in metaphysical, rather than semantic or epistemic, terms. Previous accounts of metaphysical indeterminacy have typically taken this to involve its being indeterminate which of various determinate states of affairs obtain. On my alternative account, MI involves its being determinate that an indeterminate state of affairs obtains. I more specifically suggest that MI involves an object's having a determinable (...) property, but not having any unique determinate of that determinable. I motivate the needed extension of the traditional understanding of determinables, then argue that a determinable-based account of MI accommodates, in illuminating fashion, both ‘glutty’ and ‘gappy’ cases of MI, while satisfactorily treating concerns about MI stemming from Evans’ argument and the problem of the many. (shrink)

Ted Sider has famously argued that existence, in the unrestricted sense of ontology, cannot be vague, as long as vagueness is modeled by means of precisifications. The first section of Chapter 9 exposes some controversial assumptions underlying Sider’s alleged reductio of vague existence. The upshot of the discussion is that, although existence cannot be vague, it can be super-vague, i.e. higher-order vague, for all orders. The second section develops and defends a novel framework, dubbed negative supervaluationary semantics, which makes room (...) for the possibility of super-vague existence. (shrink)

In this paper I will argue against a view that I call foundationalism about persistence-conditions. The core of this view is that composite physical objects have their specific persistence-conditions in virtue of these conditions being fulfilled by the object’s physical constituents at various times. I will provide two arguments – the argument from the possibility of instantaneous objects and the argument from the presence of persistence-conditions – which show that this view is untenable. These arguments will also point towards a (...) more adequate understanding of what it means for an object to have certain persistence-conditions. I will expound this understanding and suggest, on its basis, an unorthodox, hylomorphist account of the persistence-conditions of objects. (shrink)

Many of those working on moral responsibility assume that "once blameworthy, always blameworthy." They believe that blameworthiness is like diamonds: it is forever. We argue that blameworthiness is not forever; rather, it can diminish through time. We begin by showing that the view that blameworthiness is forever is best understood as the claim that personal identity is sufficient for diachronic blameworthiness. We argue that this view should be rejected because it entails that blameworthiness for past action is completely divorced from (...) the distinctive psychological features of the person at the later time. This is because on none of the leading accounts of personal identity does identity require the preservation of any distinctive psychological features, but merely requires some form of continuity. The claim that blameworthiness is forever should therefore be rejected. We then sketch an account of blameworthiness over time, and consider two objections. (shrink)

Van Inwagen proposes that besides simples only living organisms exist as composite objects. This paper suggests expanding van Inwagen’s ontology by also accepting composite objects in the case that physical bonding occurs (plus some extra conditions). Such objects are not living organ-isms but rather physical bodies. They include (approximately) the complete realm of inanimate ordinary objects, like rocks and tables, as well as inanimate scientific objects, like atoms and mol-ecules, the latter filling the ontological gap between simples and organisms in (...) van Inwagen’s origi-nal picture. We thus propose a compositional pluralism claiming that composition arises if and on-ly if bonding or life occurs. (shrink)

There are writers in both metaphysics and algorithmic information theory (AIT) who seem to think that the latter could provide a formal theory of the former. This paper is intended as a step in that direction. It demonstrates how AIT might be used to define basic metaphysical notions such as *object* and *property* for a simple, idealized world. The extent to which these definitions capture intuitions about the metaphysics of the simple world, times the extent to which we think the (...) simple world is analogous to our own, will determine a lower bound for basing a metaphysics for *our* world on AIT. (shrink)

In his seminal paper, ‘Can There Be Vague Objects?’ (1978), Gareth Evans advanced an argument purporting to prove that the idea of indeterminate identity is incoherent. Aware that his argument was incomplete as it stands, Evans added a remark at the end of his paper, in which he explained how the original argument needed to be modified to arrive at an explicit contradiction. This paper aims to develop a modified version of Evans’ original argument, which I argue is more promising (...) than the modification that Evans proposed in his remark. Last, a structurally similar argument against the idea of indeterminate existence is presented. (shrink)

In a series of papers, Elizabeth Barnes and Robert Williams have developed a theory of metaphysical vagueness in which they argue for legitimacy of vague object and indeterminate identity. In his recent paper, Ken Akiba raises two objections against Barnes-Williams theory, concluding that it is ill-conceived and wrong-headed. In one objection, he argues that the theory implies indeterminate identity between referentially determinate objects to which λ-abstraction is applicable, and hence Evans’ argument ultimately goes through. In the other, he objects that (...) Barnes-Williams theory also fails to block Salmon’s argument. This paper discusses the two objections. It argues that there are legitimate reasons for rejecting both, and hence to revive Barnes-Williams theory. Furthermore, it is shown that the objections, while unsuccessful, are helpful in revealing the limitations of Barnes-Williams theory. (shrink)

Vague Objects and Vague Identity: New Essays on Ontic Vagueness By AkibaKen and AbasnezhadAliSpringer, 2014. x + 360 pp. £117.00.

Kilimanjaro is an example of what some philosophers would call a ‘vague object’: it is only roughly 5895 m tall, its weight is not precise and its boundaries are fuzzy because some particles are neither determinately part of it nor determinately not part of it. It has been suggested that this vagueness arises as a result of semantic indecision: it is because we didn’t make up our mind what the expression “Kilimanjaro” applies to that we can truthfully say such things (...) as “It is indeterminate whether this particle is part of Kilimanjaro”. After reviewing some of the limitations of this approach, I will propose an alternative account, based on a new semantic relation—multiple reference—capable of holding in a one-many pattern between a term and several objects in the domain. I will explain how multiple reference works, what differentiates it from plural reference and how it might be used to accommodate at least some aspects of our ordinary discourse about vague objects. (shrink)

The paper provides an alternative interpretation of ‘pair points’, discussed in Beall et al., "On the ternary relation and conditionality", J. of Philosophical Logic 41(3), 595-612. Pair points are seen as points viewed from two different ‘perspectives’ and the latter are explicated in terms of two independent valuations. The interpretation is developed into a semantics using pairs of Kripke models (‘pair models’). It is demonstrated that, if certain conditions are fulfilled, pair models are validity-preserving copies of positive substructural models. This (...) yields a general soundness and completeness result for a variety of (positive) substructural logics with respect to multimodal Kripke frames with binary accessibility relations. In addition, an epistemic interpretation of pair models is provided. (shrink)

The aim of this essay is to argue that, if a robust form of moral realism is true, then moral vagueness is ontic vagueness. The argument is by elimination: I show that neither semantic nor epistemic approaches to moral vagueness are satisfactory.

Die gegenwärtig unter dem Titel ›Realismus‹ geführten Debatten in der Philosophie befinden sich nach allgemeiner Ansicht in einem Zustand größter Verwirrung, so daß es nützlich erscheint, ein wenig Ordnung in die theoretischen Optionen zu bringen bevor man für die eine oder andere Auffassung Partei ergreift. In der vorliegenden Arbeit wird dafür argumentiert, daß sich ein systematisch zusammenhängendes Zentrum dieser Debatten mit Hilfe des Begriffes der Referenz ordnen läßt. Nach der Analyse einiger klassischer Positionen soll ein Rahmen erstellt werden, innerhalb dessen (...) die Positionen eingeordnet und die zentralen Probleme fruchtbar diskutiert werden können. Zu diesem Zwecke ist es erforderlich, für die Einordnung der Positionen theoretische Kriterien zu benennen, die sich an den Problemen orientieren von denen hier argumentiert wird, das sie zentral seien. Sehr knapp ausgedrückt wird hier die Auffassung vertreten, Realismus sei als metaphysische These aufzufassen, welche eine von menschlichen epistemischen und semantischen Möglichkeiten unabhängige Existenz behauptet; in den gegenwärtigen Debatten typischerweise die Existenz einer Art von Dingen, nicht die eines individuellen Gegenstandes. Diese metaphysische These wird jedoch in der gegenwärtigen Debatte mit semantischen Argumenten untermauert, bzw. angegriffen und jene semantischen Argumente wiederum verwenden epistemische Erwägungen – die Frage betreffend, was man wissen kann und was nicht. Der Beginn der gegenwärtigen Realismusdebatten mit der soeben skizzierten zentralen Stellung semantischer Argumente ist, der hier vertretenen Auffassung zufolge, die Kritik am traditionellen Fregeschen Referenzbegriff durch Kripke und den frühen Putnam um 1970 (Kap. 2). Aus dieser neu zu bewertenden Kritik und der von den Autoren daraus entwickelten externalistischen realistischen Semantik für Artausdrücke läßt sich das erste Kriterium für eine Position in einer Realismusdebatte ableiten und klären (Kap. 3): Hält man die fragliche Art für eine natürliche Art und meint also, sie habe ihren ›Zusammenhalt‹ von Natur aus? Wenn ja, dann ist die fragliche Position eine realistische (das Kriterium ist dank des engen Zusammenhangs von Realismus und Externalismus sowohl hinreichend als auch notwendig). Hält man die Art nicht für eine natürliche Art, ist man Antirealist. Damit geht jeweils not- wendig eine bestimmte Semantik für den auf die Art referierenden Ausdruck einher. Es zeigt sich zugleich, daß es zwei Varianten des Realismus zu unterscheiden gilt, die hier als klassischer bzw. als moderater Realismus bezeichnet werden. Im folgenden (Kap. 4.1) wird argumentiert, daß der Begriff der Wahrheit nicht eigentlich der zentrale Punkt in den in Frage stehenden Realismusdebatten sein sollte, wie vielfach behauptet wurde, sondern seine Brisanz vielmehr aus zugrundeliegenden semantischen Fragen gewinnt die also in der weiteren Aufdeckung der Kriterien die zentrale Rolle spielen müssen. In der Analyse der Kritik an der in Kap. 3 entwickelten Position des ›klassischen Realismus‹ läßt sich ein zweites unterscheidendes Kriterium für Positionen in Realismusdebatten entwickeln: begriffliche Relativität. Nach der Ablehnung von Putnams Auffassungen zu diesem Thema, werden zwei Varianten vorgeschlagen, starke und schwache begriffliche Relativität (Kap. 4.2). Die Anwendung dieses Merkmals zwingt, so wird argumentiert, in einigen Fällen zu einer Kombination einer realistischen Auffassung von Arten als natürliche mit begrifflicher Relativität. Diese mittlere Position zwischen klassischem Realismus und Antirealismus wird als »moderater Realismus« bezeichnet. Der im ersten Kriterium verwendete Begriff der natürlichen Art, und damit die Optionen in den Debatten, wird schließlich mittels einer Dis- kussion des Phänomens der Vagheit noch weiter verdeutlicht (Kap. 4.3). Ab- schließend werden die drei Optionen zusammenfassend dargestellt und ein Versuch unternommen, ihre Fruchtbarkeit für diverse Realismusdebatten anzudeuten. (shrink)

Most words in natural language are vague, that is to say, they lack sharp boundaries and, hence, they have (actual or potential) borderline cases, where the word in question neither definitely applies nor definitely fails to apply. Vagueness gives rise to paradoxes, the best known of which is the sorites (concerned with how many grains of sand are needed to make a heap). Besides offering a solution to such paradoxes, a theory of vagueness should systematically describe how the truth conditions (...) of sentences with vague terms are determined; and it should also define the right logical principles for reasoning with such sentences. This article offers an introduction to the main theories of vagueness and to the problems they have to face. (shrink)

Can identity itself be vague? Can there be vague objects? Does a positive answer to either question entail a positive answer to the other? In this paper we answer these questions as follows: No, No, and Yes. First, we discuss Evans’s famous 1978 argument and argue that the main lesson that it imparts is that identity itself cannot be vague. We defend the argument from objections and endorse this conclusion. We acknowledge, however, that the argument does not by itself establish (...) either that there cannot be vague objects or that there cannot be identity statements that are indeterminate for ontic reasons. And we further acknowledge that it does not by itself establish that there cannot be identity statements that are indeterminate in virtue of the existence of vague objects. We then go on to argue that, despite this, one who believes in vague objects cannot endorse Evans’s argument. To establish this we offer supplementary arguments that show that if vague objects exist then identity is vague, and that if identity is vague then vague objects exist. Finally we draw attention to an argument parallel to that of Evans’s, but safer, which can be employed against the putative ontic indeterminacy in identity of vague objects which can be differentiated by identity-free properties. (shrink)

Revisionary theories of logic or truth require revisionary theories of mind. This essay outlines nonclassically based theories of rational belief, desire, and decision making, singling out the supervaluational family for special attention. To see these nonclassical theories of mind in action, this essay examines a debate between David Lewis and Derek Parfit over what matters in survival. Lewis argued that indeterminacy in personal identity allows caring about psychological connectedness and caring about personal identity to amount to the same thing. The (...) essay argues that Lewis's treatment of two of Parfit's puzzle cases—degreed survival and fission—presuppose different nonclassical treatments of belief and desire. (shrink)

Peter Ludlow shows how word meanings are much more dynamic than we might have supposed, and explores how they are modulated even during everyday conversation. The resulting view is radical, and has far-reaching consequences for our political and legal discourse, and for enduring puzzles in the foundations of semantics, epistemology, and logic.

The naive theory of properties states that for every condition there is a property instantiated by exactly the things which satisfy that condition. The naive theory of properties is inconsistent in classical logic, but there are many ways to obtain consistent naive theories of properties in nonclassical logics. The naive theory of classes adds to the naive theory of properties an extensionality rule or axiom, which states roughly that if two classes have exactly the same members, they are identical. In (...) this paper we examine the prospects for obtaining a satisfactory naive theory of classes. We start from a result by Ross Brady, which demonstrates the consistency of something resembling a naive theory of classes. We generalize Brady’s result somewhat and extend it to a recent system developed by Andrew Bacon. All of the theories we prove consistent contain an extensionality rule or axiom. But we argue that given the background logics, the relevant extensionality principles are too weak. For example, in some of these theories, there are universal classes which are not declared coextensive. We elucidate some very modest demands on extensionality, designed to rule out this kind of pathology. But we close by proving that even these modest demands cannot be jointly satisfied. In light of this new impossibility result, the prospects for a naive theory of classes are bleak. (shrink)

Arguments based on Leibniz's Law seem to show that there is no room for either indefinite or contingent identity. The arguments seem to prove too much, but their conclusion is hard to resist if we want to keep Leibniz's Law. We present a novel approach to this issue, based on an appropriate modification of the notion of logical consequence.

This unique anthology of new, contributed essays offers a range of perspectives on various aspects of ontic vagueness. It seeks to answer core questions pertaining to onticism, the view that vagueness exists in the world itself. The questions to be addressed include whether vague objects must have vague identity, and whether ontic vagueness has a distinctive logic, one that is not shared by semantic or epistemic vagueness. The essays in this volume explain the motivations behind onticism, such as the plausibility (...) of mereological vagueness and indeterminacy in quantum mechanics and they offer various arguments both for and against ontic vagueness; onticism is also compared with other, competing theories of vagueness such as semanticism, the view that vagueness exists only in our linguistic representation of the world. Gareth Evans’s influential paper of 1978, “Can There Be Vague Objects?” gave a simple but cogent argument against the coherence of ontic vagueness. Onticism was subsequently dismissed by many. However, in recent years, researchers have become aware of the logical gaps in Evans’s argument and this has triggered a new wave of interest in onticism. Onticism is now widely regarded as at least a coherent view. Reflecting this growing consensus, the present anthology for the first time puts together essays that are focused on onticism and its various facets and it fills in the lacuna in the literature on vagueness, a much-discussed subject in contemporary philosophy. (shrink)

The topic of this paper is whether there is metaphysical vagueness. It is shown that it is important to distinguish between the general phenomenon of indeterminacy and the more narrow phenomenon of vagueness (the phenomenon that paradigmatically rears its head in sorites reasoning). Relatedly, it is important to distinguish between metaphysical indeterminacy and metaphysical vagueness. One can wish to allow metaphysical indeterminacy but rule out metaphysical vagueness. As is discussed in the paper, central argument against metaphysical vagueness, like those of (...) Gareth Evans and Mark Sainsbury, would if successful rule out metaphysical indeterminacy. One way to argue specifically against the possibility of metaphysical vagueness might be thought to be to argue for a specific theory of the nature of vagueness according to which vagueness is a semantic phenomenon. But it is shown that there are complications also pertaining to arguments with that structure. Toward the end of the paper, I discuss Trenton Merricks’ well-known argument against a semantic view on vagueness and for a metaphysical view. (shrink)

This dissertation explores several illuminating points of intersection between the philosophy of perception and the philosophy of vagueness. Among other things, I argue: (i) that it is entirely unhelpful to theorize about perception or consciousness using Nagelian "what it's like" talk; (ii) that a popular recent account of perceptual phenomenology (representationalism) conflicts with our best theory of vagueness (supervaluationism); (iii) that there are no vague properties, for Evans-esque reasons; (iv) that it is impossible to insert "determinacy" operators into representationalism in (...) a truth-preserving manner; and (v) that strong versions of dualism are unable to accommodate the possibility of borderline consciousness. (shrink)

Abstract. As a general theory of reasoning—and as a general theory of what holds true under every possible circumstance—logic is supposed to be ontologically neutral. It ought to have nothing to do with questions concerning what there is, or whether there is anything at all. It is for this reason that traditional Aristotelian logic, with its tacit existential presuppositions, was eventually deemed inadequate as a canon of pure logic. And it is for this reason that modern quantification theory, too, with (...) its residue of existentially loaded theorems and patterns of inference, has been claimed to suffer from a defect of logical purity. The law of non-contradiction rules out certain circumstances as impossible—circumstances in which a statement is both true and false, or perhaps circumstances where something both is and is not the case. Is this to be regarded as a further ontological bias? (shrink)

One feature of vague predicates is that, as far as appearances go, they lack sharp application boundaries. I argue that we would not be able to locate boundaries even if vague predicates had sharp boundaries. I do so by developing an idealized cognitive model of a categorization faculty which has mobile and dynamic sortals (`classes', `concepts' or `categories') and formally prove that the degree of precision with which boundaries of such sortals can be located is inversely constrained by their flexibility. (...) Given the literature, it is plausible that we are appropriately like the model. Hence, an inability to locate sharp boundaries is not necessarily because there are none; boundaries could be sharp and it is plausible that we would nevertheless be unable to locate them. (shrink)

On the opposition between de re and de dicto conceptions of vagueness, with special reference to their bearing on the tasks of ontology.

We discuss arguments against the thesis that the world itself can be vague. The first section of the paper distinguishes dialectically effective from ineffective arguments against metaphysical vagueness. The second section constructs an argument against metaphysical vagueness that promises to be of the dialectically effective sort: an argument against objects with vague parts. Firstly, cases of vague parthood commit one to cases of vague identity. But we argue that Evans' famous argument against will not on its own enable one to (...) complete the reductio in the present context. We provide a metaphysical premise that would complete the reductio, but note that it seems deniable. We conclude by drawing general morals from our case study. (shrink)

Lynne Rudder Baker’s Constitution View of human persons has come under much recent scrutiny. Baker argues that each human person is constituted by, but not identical to, a human animal. Much of the critical discussion of Baker’s Constitution View has focused upon this aspect of her account. Less has been said about the positive diachronic account of personal identity offered by Baker. Baker argues that it is sameness of what she labels ‘first-person perspective’ that is essential to understanding personal identity (...) over time . Baker claims that her account avoids the commitment to indeterminacy of personal identity entailed by the psychological account. Further, the psychological account, but not her account, is plagued by what Baker labels the ‘duplication problem’. In the end, I argue that neither of these considerations forces us to renounce the psychological account and adopt Baker’s favored account. (shrink)