• Worldly Indeterminacy: A Rough Guide
    In Frank Jackson & Graham Priest (eds.), Lewisian Themes: The Philosophy of David K. Lewis. pp. 196-209. 2004.
    This paper defends the idea that there might be vagueness or indeterminacy in the world itself---as opposed to merely in our representations of the world---against the charges of incoherence and unintelligibility. First we consider the idea that the world might contain vague *properties and relations*; we show that this idea is already implied by certain well-understood views concerning the semantics of vague predicates (most notably the fuzzy view). Next we consider the idea that the world mi…Read more
  • Worldly Indeterminacy: A Rough Guide
    Australasian Journal of Philosophy 82 (Issue in Honour of David Lewis): 185-198. 2004.
    This paper defends the idea that there might be vagueness or indeterminacy in the world itself---as opposed to merely in our representations of the world---against the charges of incoherence and unintelligibility. First we consider the idea that the world might contain vague *properties and relations*; we show that this idea is already implied by certain well-understood views concerning the semantics of vague predicates (most notably the fuzzy view). Next we consider the idea that the world mi…Read more
  •  3
    Why Time Travellers (Still) Cannot Change the Past
    Revista Portuguesa de Filosofia 71 (70th Anniversary Issue on Metaph): 677-94. 2015.
    In an earlier paper I argued that time travellers cannot change the past: alleged models of changing the past either fall into contradiction or else involve avoiding, not changing, the past. Goddu has responded to my argument, maintaining that his hypertime model involves time travellers changing (not avoiding) the past. In the present paper I first discuss what would be required to substantiate the claim that a given model involves changing rather than avoiding the past. I then consider Godd…Read more
  •  2
    Different formal tools are useful for different purposes. For example, when it comes to modelling degrees of belief, probability theory is a better tool than classical logic; when it comes to modelling the truth of mathematical claims, classical logic is a better tool than probability theory. In this paper I focus on a widely used formal tool and argue that it does not provide a good model of a phenomenon of which many think it does provide a good model: I shall argue that while supervaluationis…Read more
  •  6
    A common objection to theories of vagueness based on fuzzy logics centres on the idea that assigning a single numerical degree of truth -- a real number between 0 and 1 -- to each vague statement is excessively precise. A common objection to Bayesian epistemology centres on the idea that assigning a single numerical degree of belief -- a real number between 0 and 1 -- to each proposition is excessively precise. In this paper I explore possible parallels between these objections. In particular…Read more
  •  10
    Alethic Pluralism and Logical Consequence
    In Igor Sedlár & Martin Blicha (eds.), The Logica Yearbook 2019. forthcoming.
    It has been argued that alethic pluralists -- who hold that there are several distinct truth properties -- face a problem when it comes to defining validity. Via consideration of the classical concept of logical consequence, and of strategies for defining validity in many-valued logics, this paper proposes two new kinds of solution to the problem.
  •  109
    Vagueness and Degrees of Truth
    Oxford University Press. 2008.
    In VAGUENESS AND DEGREES OF TRUTH, Nicholas Smith develops a new theory of vagueness: fuzzy plurivaluationism. A predicate is said to be VAGUE if there is no sharply defined boundary between the things to which it applies and the things to which it does not apply. For example, 'heavy' is vague in a way that 'weighs over 20 kilograms' is not. A great many predicates -- both in everyday talk, and in a wide array of theoretical vocabularies, from law to psychology to engineering -- are vague. Smi…Read more
  •  11
    Review of Dominic Hyde Vagueness, Logic and Ontology (Ashgate, 2008) (review)
    Bulletin of Symbolic Logic 16 (4): 531-533. 2010.
  •  12
    A Theory of Propositions
    Logic and Logical Philosophy 25 (1): 83-125. 2016.
    In this paper I present a new theory of propositions, according to which propositions are abstract mathematical objects: well-formed formulas together with models. I distinguish the theory from a number of existing views and explain some of its advantages  chief amongst which are the following. On this view, propositions are unified and intrinsically truth-bearing. They are mind- and language-independent and they are governed by logic. The theory of propositions is ontologically innocent. It ma…Read more
  •  21
    A logical framework for graded predicates
    with Petr Cintula and Carles Noguera
    In Alexandru Baltag, Jeremy Seligman & Tomoyuki Yamada (eds.), Logic, Rationality, and Interaction: LORI 2017, Springer. pp. 3-16. 2017.
    In this position paper we present a logical framework for modelling reasoning with graded predicates. We distinguish several types of graded predicates and discuss their ubiquity in rational interaction and the logical challenges they pose. We present mathematical fuzzy logic as a set of logical tools that can be used to model reasoning with graded predicates, and discuss a philosophical account of vagueness that makes use of these tools. This approach is then generalized to other kinds of grade…Read more
  •  51
    (No abstract is available for this citation)
  •  33
    I have argued for a picture of decision theory centred on the principle of Rationally Negligible Probabilities. Isaacs argues against this picture on the grounds that it has an untenable implication. I first examine whether my view really has this implication; this involves a discussion of the legitimacy or otherwise of infinite decisions. I then examine whether the implication is really undesirable and conclude that it is not
  •  19
    Vagueness, Logic and Ontology by Dominic Hyde (review)
    Bulletin of Symbolic Logic 16 (4): 531-532. 2010.
  •  229
    The Paradoxes of Time Travel
    with Ken Perszyk
    In Public lecture at Te Papa (National Museum of New Zealand), . 2001.
    Humans have long been fascinated by the idea of visiting the past and of seeing what the future will bring. Time travel has been one of the most popular themes of science fiction. Most people have seen the TV series ‘Dr Who’ or ‘Quantum Leap’ or ‘Star Trek’. You’ve probably seen one of the ‘Back to the Future’ or ‘Terminator’ movies, or ‘Twelve Monkeys’. Time travel narratives provide fascinating plots, which exercise our imaginations in ever so many ways. But is the idea of travelling forward a…Read more
  •  150
    One of the most striking differences between Frege's Begriffsschrift (logical system) and standard contemporary systems of logic is the inclusion in the former of the judgement stroke: a symbol which marks those propositions which are being asserted , that is, which are being used to express judgements . There has been considerable controversy regarding both the exact purpose of the judgement stroke, and whether a system of logic should include such a symbol. This paper explains the intended rol…Read more
  •  191
    Degree of belief is expected truth value
    In Sebastiano Moruzzi & Richard Dietz (eds.), Cuts and Clouds. Vaguenesss, its Nature and its Logic, Oxford University Press. pp. 491--506. 2009.
    A number of authors have noted that vagueness engenders degrees of belief, but that these degrees of belief do not behave like subjective probabilities. So should we countenance two different kinds of degree of belief: the kind arising from vagueness, and the familiar kind arising from uncertainty, which obey the laws of probability? I argue that we cannot coherently countenance two different kinds of degree of belief. Instead, I present a framework in which there is a single notion of degree of…Read more
  •  81
    Logic: The Laws of Truth
    Princeton University Press. 2012.
    Logic is essential to correct reasoning and also has important theoretical applications in philosophy, computer science, linguistics, and mathematics. This book provides an exceptionally clear introduction to classical logic, with a unique approach that emphasizes both the hows and whys of logic. Here Nicholas Smith thoroughly covers the formal tools and techniques of logic while also imparting a deeper understanding of their underlying rationales and broader philosophical significance. In addit…Read more
  •  24
    Doubts about `Uncertainty without all the doubt'
    Mind and Language Symposium. 2015.
    The storage hypothesis—as described by Norby—is a descriptive thesis (for it yields systematic predictions of human behaviour across a wide range of situations) that has as a core commitment that degrees of belief are stable, persistent states. It is not clear to me that such a view is widely held in philosophy. If the storage hypothesis is not widely held, then arguments against it become less interesting. But is Norby’s argument against the view compelling in any case? I shall argue that …Read more
  •  101
    Logic: The Drill
    Princeton University Press. 2012.
    Contains exercises and solutions to accompany Logic: The Laws of Truth by Nicholas J. J. Smith (Princeton University Press, 2012).
  •  36
    Consonance and Dissonance in Solutions to the Sorites
    In Otavio Bueno & Ali Abasnezhad (eds.), On the Sorites Paradox, Springer. forthcoming.
    A requirement on any theory of vagueness is that it solve the sorites paradox. It is generally agreed that there are two aspects to such a solution: one task is to locate the error in the sorites argument; the second task is to explain why the sorites reasoning is a paradox rather than a simple mistake. I argue for a further constraint on approaches to the second task: they should conform to the standard modus operandi in formal semantics, in which the semantic theory one develops is t…Read more
  •  88
    I’d Do Anything to Change the Past (But I Can’t Do ‘That')
    American Philosophical Quarterly 54 (2): 153-168. 2017.
    This paper addresses a worry about backwards time travel. The worry is that there is something mysteriously inexplicable about the combination of commonplace events that will inevitably conspire to prevent the time traveler from doing something impossible such as killing her younger self. The worry is first distinguished from other problems for backwards time travel concerning its alleged impossibility or improbability. It is then shown that the worry is misplaced: there is in fact no real probl…Read more
  •  23
    Truth via Satisfaction?
    In Pavel Arazim & Tomas Lavicka (eds.), The Logica Yearbook 2016, College Publications. pp. 273-287. 2017.
    One of Tarski’s stated aims was to give an explication of the classical conception of truth—truth as ‘saying it how it is’. Many subsequent commentators have felt that he achieved this aim. Tarski’s core idea of defining truth via satisfaction has now found its way into standard logic textbooks. This paper looks at such textbook definitions of truth in a model for standard first-order languages and argues that they fail from the point of view of explication of the classical notion of truth…Read more
  •  75
    Many-Valued Logics
    In Gillian Russell & Delia Graff Fara (eds.), The Routledge Companion to Philosophy of Language, Routledge. pp. 636--51. 2012.
    A many-valued (aka multiple- or multi-valued) semantics, in the strict sense, is one which employs more than two truth values; in the loose sense it is one which countenances more than two truth statuses. So if, for example, we say that there are only two truth values—True and False—but allow that as well as possessing the value True and possessing the value False, propositions may also have a third truth status—possessing neither truth value—then we have a many-valued semantics in the loose but…Read more
  •  37
    This paper presents a new solution to the problems for orthodox decision theory posed by the Pasadena game and its relatives. I argue that a key question raised by consideration of these gambles is whether evaluative compositionality (as I term it) is a requirement of rationality: is the value that an ideally rational agent places on a gamble determined by the values that she places on its possible outcomes, together with their mode of composition into the gamble (i.e. the probabilities assigned…Read more
  •  96
    Measuring and Modelling Truth
    American Philosophical Quarterly 49 (4): 345-356. 2012.
    Philosophers, linguists and others interested in problems concerning natural language frequently employ tools from logic and model theory. The question arises as to the proper interpretation of the formal methods employed—of the relationship between, on the one hand, the formal languages and their set-theoretic models and, on the other hand, the objects of ultimate interest: natural language and the meanings and truth conditions of its constituent words, phrases and sentences. Two familiar answe…Read more
  •  20
    Time Travel
    In Edward N. Zalta (ed.), The Stanford Encyclopedia of Philosophy, . 2013.
    There is an extensive literature on time travel in both philosophy and physics. Part of the great interest of the topic stems from the fact that reasons have been given both for thinking that time travel is physically possible—and for thinking that it is logically impossible! This entry deals primarily with philosophical issues; issues related to the physics of time travel are covered in the separate entries on time travel and modern physics and time machines. We begin with the definitional ques…Read more
  •  38
    In the context of classical (crisp, precise) sets, there is a familiar connection between the notions of counting, ordering and cardinality. When it comes to vague collections, the connection has not been kept in central focus: there have been numerous proposals regarding the cardinality of vague collections, but these proposals have tended to be discussed in isolation from issues of counting and ordering. My main concern in this paper is to draw focus back onto the connection between …Read more
  •  7
    Reply to Francesco Paoli’s Comments on 'Fuzzy Logic and Higher-Order Vagueness'
    In Petr Cintula, Christian G. Fermüller, Lluis Godo & Petr Hájek (eds.), Understanding Vagueness: Logical, Philosophical and Linguistic Perspectives, College Publications. pp. 37-40. 2011.
  •  5
    Reply to Libor Běhounek’s Comments on 'Fuzzy Logic and Higher-Order Vagueness'
    In Petr Cintula, Christian G. Fermüller, Lluis Godo & Petr Hájek (eds.), Understanding Vagueness: Logical, Philosophical and Linguistic Perspectives, College Publications. pp. 29-32. 2011.