• Knowing how things might have been
    Synthese 1-19. forthcoming.
    I know that I could have been where you are right now and that you could have been where I am right now, but that neither of us could have been turnips or natural numbers. This knowledge of metaphysical modality stands in need of explanation. I will offer an account based on our knowledge of the natures, or essencess, of things. I will argue that essences need not be viewed as metaphysically bizarre entities; that we can conceptualise and refer to essences; and that we can gain knowledge of them…Read more
  • Essential bundle theory and modality
    Synthese 1-16. 2018.
    Bundle theories identify material objects with bundles of properties. On the traditional approach, these are the properties possessed by that material object. That view faces a deep problem: it seems to say that all of an object’s properties are essential to it. Essential bundle theory attempts to overcome this objection, by taking the bundle as a specification of the object’s essential properties only. In this paper, I show that essential bundle theory faces a variant of the objection. To avoid…Read more
  • Material objects and essential bundle theory
    Philosophical Studies. forthcoming.
    In this paper we present a new metaphysical theory of material objects. On our theory, objects are bundles of property instances, where those properties give the nature or essence of that object. We call the theory essential bundle theory. Property possession is not analysed as bundle-membership, as in traditional bundle theories, since accidental properties are not included in the object’s bundle. We have a different story to tell about accidental property possession. This move reaps many benef…Read more
  • Modal realism, still at your convenience
    with Harold Noonan
    Analysis 77 (2): 299-303. 2017.
    Divers presents a set of de re modal truths which, he claims, are inconvenient for Lewisean modal realism. We argue that there is no inconvenience for Lewis.
  • What Truth Is
    Oxford University Press. 2018.
    Mark Jago presents and defends a novel theory of what truth is, in terms of the metaphysical notion of truthmaking. This is the relation which holds between a truth and some entity in the world, in virtue of which that truth is true. By coming to an understanding of this relation, he argues, we gain better insight into the metaphysics of truth. The first part of the book discusses the property being true, and how we should understand it in terms of truthmaking. The second part focuses on truthma…Read more
  • Propositions as Truthmaker Conditions
    Argumenta 2 (2): 293-308. 2017.
    Propositions are often aligned with truth-conditions. The view is mistaken, since propositions discriminate where truth conditions do not. Propositions are hyperintensional: they are sensitive to necessarily equivalent differences. I investigate an alternative view on which propositions are truthmaker conditions, understood as sets of possible truthmakers. This requires making metaphysical sense of merely possible states of affairs. The theory that emerges illuminates the semantic phenomena of s…Read more
  • Setting the Facts Straight
    Journal of Philosophical Logic 40 (1): 33-54. 2011.
    Substantial facts are not well-understood entities. Many philosophers object to their existence on this basis. Yet facts, if they can be understood, promise to do a lot of philosophical work: they can be used to construct theories of property possession and truthmaking, for example. Here, I give a formal theory of facts, including negative and logically complex facts. I provide a theory of reduction similar to that of the typed λ -calculus and use it to provide identity conditions for facts. Thi…Read more
  • Are Impossible Worlds Trivial?
    In Vit Puncochar & Petr Svarny (eds.), The Logica Yearbook 2012, College Publications. 2013.
    Theories of content are at the centre of philosophical semantics. The most successful general theory of content takes contents to be sets of possible worlds. But such contents are very coarse-grained, for they cannot distinguish between logically equivalent contents. They draw intensional but not hyperintensional distinctions. This is often remedied by including impossible as well as possible worlds in the theory of content. Yet it is often claimed that impossible worlds are metaphysically obscu…Read more
  • Hyperintensional propositions
    Synthese 192 (3): 585-601. 2015.
    Propositions play a central role in contemporary semantics. On the Russellian account, propositions are structured entities containing particulars, properties and relations. This contrasts sharply with the sets-of-possible-worlds view of propositions. I’ll discuss how to extend the sets-of-worlds view to accommodate fine-grained hyperintensional contents. When this is done in a satisfactory way, I’ll argue, it makes heavy use of entities very much like Russellian tuples. The two notions of propo…Read more
  • Predictive accounts of belief ascription, either following the principle of charity or Dennett's intentional stance, have proved popular recently. However, such accounts require us first to treat agents as perfectly rational agents and then revise this assumption as appropriate. I argue that such downwards revision is no easy task and that several proposed accounts are not satisfactory. I propose a way of characterising agent's belief states which shares Dennett's approach but avoids treating ag…Read more
  • The Truthmaker Non-Maximalist's Dilemma
    Mind 121 (484): 903-918. 2012.
    Amongst those who feel the pull of the truthmaker principle (that truths require for their truth a truthmaker to exist), there is disagreement as to whether it applies to all truths or merely to some distinguished subset. Those in the latter camp, the non-maximalists, argue that there are no ducks in my bath is true not because of something’s existence, but because of the lack of ducks in my bath. Maximalists, by contrast, insist that truths are made true by something’s existence, and so appear …Read more
  • The Impossible: An Essay on Hyperintensionality
    Oxford University Press. 2014.
    Mark Jago presents an original philosophical account of meaningful thought: in particular, how it is meaningful to think about things that are impossible. We think about impossible things all the time. We can think about alchemists trying to turn base metal to gold, and about unfortunate mathematicians trying to square the circle. We may ponder whether God exists; and philosophers frequently debate whether properties, numbers, sets, moral and aesthetic qualities, and qualia exist. In many philo…Read more
  • Impossible Worlds
    Noûs 47 (3): 713-728. 2013.
    Impossible worlds are representations of impossible things and impossible happenings. They earn their keep in a semantic or metaphysical theory if they do the right theoretical work for us. As it happens, a worlds-based account provides the best philosophical story about semantic content, knowledge and belief states, cognitive significance and cognitive information, and informative deductive reasoning. A worlds-based story may also provide the best semantics for counterfactuals. But to function …Read more
  • Resource-bounded belief revision and contraction
    In P. Torroni, U. Endriss, M. Baldoni & A. Omicini (eds.), Declarative Agent Languages and Technologies III, Springer. pp. 141--154. 2006.
    Agents need to be able to change their beliefs; in particular, they should be able to contract or remove a certain belief in order to restore consistency to their set of beliefs, and revise their beliefs by incorporating a new belief which may be inconsistent with their previous beliefs. An influential theory of belief change proposed by Alchourron, G¨ardenfors and Makinson (AGM) [1] describes postulates which a rational belief revision and contraction operations should satisfy. The AGM postulat…Read more
  • Joe Salerno (ed): New essays on the knowability paradox (review)
    Journal of Logic, Language and Information 19 (3): 383-387. 2010.
  • Epistemic logic for rule-based agents
    Journal of Logic, Language and Information 18 (1): 131-158. 2009.
    The logical omniscience problem, whereby standard models of epistemic logic treat an agent as believing all consequences of its beliefs and knowing whatever follows from what else it knows, has received plenty of attention in the literature. But many attempted solutions focus on a fairly narrow specification of the problem: avoiding the closure of belief or knowledge, rather than showing how the proposed logic is of philosophical interest or of use in computer science or artificial intelligence.…Read more
  • Indexicals, fictions, and ficta
    Dialectica 57 (2). 2003.
    We defend the view that an indexical uttered by an actor works on the model of deferred reference. If it defers to a character which does not exist, it is an empty term, just as ‘Hamlet’ and ‘Ophelia’ are. The utterance in which it appears does not express a proposition and thus lacks a truth value. We advocate an ontologically parsimonious, anti-realist, position. We show how the notion of truth in our use and understanding of indexicals (and fictional names) as they appear within a fiction is …Read more
  • Recent Work in Relevant Logic
    Analysis 73 (3): 526-541. 2013.
    This paper surveys important work done in relevant logic in the past 10 years.
  • The Conjunction and Disjunction Theses
    Mind 118 (470): 411-415. 2009.
    Rodriguez-Pereyra (2006) argues for the disjunction thesis but against the conjunction thesis. I argue that accepting the disjunction thesis undermines his argument against the conjunction thesis.
  • Advanced Modalizing Problems
    Mind 125 (499): 627-642. 2016.
    I present an internal problem for David Lewis’s genuine modal realism. My aim is to show that his analysis of modality is inconsistent with his metaphysics. I consider several ways of modifying the Lewisian analysis of modality, but argue that none are successful. I argue that the problem also affects theories related to genuine modal realism, including the stage theory of persistence and modal fictionalism.
  • Pictures and Nonsense
    Philosophy Now 58 7-9. 2006.
  • Indexicals, fictions, and ficta
    Dialectica 52 (2): 121-136. 2003.
    We defend the view that an indexical uttered by an actor works on the model of deferred reference. If it defers to a character which does not exist, it is an empty term, just as ‘Hamlet’ and ‘Ophelia’ are. The utterance in which it appears does not express a proposition and thus lacks a truth value. We advocate an ontologically parsimonious, anti-realist, position. We show how the notion of truth in our use and understanding of indexicals (and fictional names) as they appear within a fiction is …Read more
  • Being Positive About Negative Facts
    with Stephen Barker
    Philosophy and Phenomenological Research 85 (1): 117-138. 2012.
    Negative facts get a bad press. One reason for this is that it is not clear what negative facts are. We provide a theory of negative facts on which they are no stranger than positive atomic facts. We show that none of the usual arguments hold water against this account. Negative facts exist in the usual sense of existence and conform to an acceptable Eleatic principle. Furthermore, there are good reasons to want them around, including their roles in causation, chance-making and truth-making, and…Read more
  • Preference-based belief revision for rule-based agents
    with Natasha Alechina and Brian Logan
    Synthese 165 (2): 159-177. 2008.
    Agents which perform inferences on the basis of unreliable information need an ability to revise their beliefs if they discover an inconsistency. Such a belief revision algorithm ideally should be rational, should respect any preference ordering over the agent’s beliefs (removing less preferred beliefs where possible) and should be fast. However, while standard approaches to rational belief revision for classical reasoners allow preferences to be taken into account, they typically have quite hig…Read more
  • The Accidental Properties of Numbers and Properties
    with Harold Noonan
    Thought: A Journal of Philosophy 1 (2): 134-140. 2012.
    According to genuine modal realism, some things (including numbers and properties) lack distinct counterparts in different worlds. So how can they possess any of their properties contingently? Egan (2004) argues that to explain such accidental property possession, the genuine modal realist must depart from Lewis and identify properties with functions, rather than with sets of possibilia. We disagree. The genuine modal realist already has the resources to handle Egan's proposed counterexamples. A…Read more
  • Monism and Material Constitution
    with Stephen Barker
    Pacific Philosophical Quarterly 95 (1): 189-204. 2014.
    Are the sculpture and the mass of gold which permanently makes it up one object or two? In this article, we argue that the monist, who answers ‘one object’, cannot accommodate the asymmetry of material constitution. To say ‘the mass of gold materially constitutes the sculpture, whereas the sculpture does not materially constitute the mass of gold’, the monist must treat ‘materially constitutes’ as an Abelardian predicate, whose denotation is sensitive to the linguistic context in which it appear…Read more
  • Review: Jonathan A. Waskan: Models and Cognition (review)
    Mind 118 (469): 220-225. 2009.
  • Logical information and epistemic space
    Synthese 167 (2). 2009.
    Gaining information can be modelled as a narrowing of epistemic space . Intuitively, becoming informed that such-and-such is the case rules out certain scenarios or would-be possibilities. Chalmers’s account of epistemic space treats it as a space of a priori possibility and so has trouble in dealing with the information which we intuitively feel can be gained from logical inference. I propose a more inclusive notion of epistemic space, based on Priest’s notion of open worlds yet which contains …Read more
  • From nature to grounding
    In Ricki Leigh Bliss & Graham Priest (eds.), Reality and its Structure, Oxford University Press. pp. 199-216. 2018.
    Grounding is a powerful metaphysical concept; yet there is widespread scepticism about the intelligibility of the notion. In this paper, I propose an account of an entity’s nature or essence, which I then use to provide grounding conditions for that entity. I claim that an understanding of an entity’s nature, together with an account of how logically complex entities are grounded, provides all we need to understand how that entity is grounded. This approach not only allows us to say what grounds…Read more