It is widely held that there is a problem of talking about or otherwise representing things that not exist. But what exactly is this problem? This paper presents a formulation of the problem in terms of the conflict between the fact that there are truths about non-existent things and the fact that truths must be answerable to reality, how things are. Given this, the problem of singular negative existential statements is no longer the central or most difficult aspect of the (...) problem of non-existence, despite what some philosophers say. (shrink)

Fictionalism about fictional characters is a view according to which all claims ostensibly about fictional characters are in fact claims about the content of a story. Claims that appear to refer to or quantify over fictional objects contain an implicit prefix of the form “according to such-and-such story. In.

This paper presents a bivalent extensional semantics for positive free logic without resorting to the philosophically questionable device of using models endowed with a separate domain of "non-existing" objects. The models here introduced have only one (possibly empty) domain, and a partial reference function for the singular terms (that might be undefined at some arguments). Such an approach provides a solution to an open problem put forward by Lambert, and can be viewed as supplying a version of parametrized truth non (...) unlike the notion of "truth at world" found in modal logic. A model theory is developed, establishing compactness, interpolation (implying a strong form of Beth definability), and completeness (with respect to a particular axiomatization). (shrink)

This chapter focuses on alternative logics. It discusses a hierarchy of logical reform. It presents case studies that illustrate particular aspects of the logical revisionism discussed in the chapter. The first case study is of intuitionistic logic. The second case study turns to quantum logic, a system proposed on empirical grounds as a resolution of the antinomies of quantum mechanics. The third case study is concerned with systems of relevance logic, which have been the subject of an especially detailed reform (...) program. Finally, the fourth case study is paraconsistent logic, perhaps the most controversial of serious proposals. (shrink)

Kearns (2021) reconstructs Berkeley’s (1713) Master Argument as a formally valid argument against the Materialist Thesis, with the key premise the Distinct Conceivability Thesis, namely the thesis that truths about sensible objects having or lacking thinkable qualities are (distinctly) conceivable and as its conclusion that all sensible objects are conceived. It will be shown that Distinct Conceivability Thesis entails the Reduction Thesis, which states that de dicto propositional (ordinary or distinct) conceivability reduces to de re propositional (ordinary or distinct) conceivability. (...) While Kearns (2021) set out to avoid the confusion of a de re claim with a de dicto claim, which Prior (1955) accused Berkeley of, Kearns can be accused of making a similar conceptual confusion. (shrink)

Semantic externalism in the style of McDowell and Evans faces a puzzle formulated by Pryor: to explain that a sentence such as 'Jack exists' is only a posteriori knowable, despite being logically entailed by the seemingly logical truth 'Jack is self-identical', and hence being itself a logical truth and therefore a priori knowable. Free logics can dissolve the puzzle. Moreover, Pryor has argued that the existentially hedged 'If Jack exists, then Jack is self-identical', when properly formalised, is a logical truth (...) in a system of neutral free logic and therefore a priori knowable, while it does not entail that Jack exists. The latter holds also for negative free logic. In response, Yeakel has argued that on any system of neutral free logic existence hedges will either entail some unwanted existence claims or they will not entail some wanted existence claims. The dilemma also holds for any non-positive free logic. It will be shown that the extension of one of the systems of neutral free logic with a truth operator escapes Yeakel's dilemma, whereas no other non-positive free logic when extended with the truth operator does the same (or it breaks quantifier exchangeability). (shrink)

Thanks to the Inlaks Foundation in India, I was able to do my doctoral research on Our Talk About Nonexistents at Oxford in the early eighties. The two greatest philosophers of that heaven of analytical philosophy - Peter Strawson and Michael Dummett - supervised my work, reading and criticising all the fledgling philosophy that I wrote during those three years. At Sir Peter's request, Gareth Evans, shortly before his death, lent me an unpublished transcript of Kripke's John Locke Lectures. Work (...) on the Appendix about Indian Philosophy was supervised by the late Professor Bimal Krishna Matilal with whom informal but intense philosophical conversations used to spill over into dinner at his place almost every other day. It was Professor Matilal who sent me, over a summer, to study a tough Navya-Nyaya text under his own Nyaya teacher Pandit Visvabandhu Tarkatirtha at Calcutta. All four of these teachers were as kind to me as my life-long mentor in philosophy Professor Pranab Kumar Sen, whose clarity and depth remain the unreachable regu lative ideal of my intellect. When I came back to India, my life became blissfully free of the agonising anxiety to publish, until, after a conference at Jadavpur University where I gave an impromptu paper, ironically enough, on Non-doings, I met Derek Parfit. He had a six-hour conversation with me, explicitly planning my life. Five years had already elapsed since I had finished my D. Phil, but Derek read my thesis and liked it. (shrink)

In this paper, I will defend a new compositional semantics for single-domain free logic. This semantics makes use of a distinction between the semantic value of a singular term and its semantic referent. The semantic value of a singular term is conceived of as a set that either contains the semantic referent or no element at all. The semantic referent is the object that the term designates. Before I will introduce this new semantics for single-domain predicate and an S5-type modal (...) logic in detail, I will present five related problems of compositionality of the standard semantics for these logical systems. After that I will show in detail how my new proposed alternative semantics can be used to solve nearly all of the outlined five problems. (shrink)

Free logics are a family of first-order logics which came about as a result of examining the existence assumptions of classical logic (Hintikka _The Journal of Philosophy_, _56_, 125–137 1959 ; Lambert _Notre Dame Journal of Formal Logic_, _8_, 133–144 1967, 1997, 2001 ). What those assumptions are varies, but the central ones are that (i) the domain of interpretation is not empty, (ii) every name denotes exactly one object in the domain and (iii) the quantifiers have existential import. Free (...) logics reject the claim that names need to denote in (ii). _Positive_ free logic concedes that some atomic formulas containing non-denoting names (including self-identity) are true, _negative_ free logic treats them as uniformly false, and _neutral_ free logic as taking a third value. There has been a renewed interest in analyzing proof theory of free logic in recent years, based on intuitionistic logic in Maffezioli and Orlandelli (_Bulletin of the Section of Logic_, _48_(2), 137–158 2019 ) as well as classical logic in Pavlović and Gratzl (_Journal of Philosophical Logic_, _50_, 117–148 2021 ), there for the positive and negative variants. While the latter streamlines the presentation of free logics and offers a more unified approach to the variants under consideration, it does not cover neutral free logic, since there is some lack of both clear formal intuitions on the semantic status of formulas with empty names, as well as a satisfying account of the conditional in this context. We discuss extending the results to this third major variant of free logics. We present a series of G3 sequent calculi adapted from Fjellstad (_Studia Logica_, _105_(1), 93–119 2017, _Journal of Applied Non-Classical Logics_, _30_(3), 272–289 2020 ), which possess all the desired structural properties of a good proof system, including admissibility of contraction and all versions of the cut rule. At the same time, we maintain the unified approach to free logics and moreover argue that greater clarity of intuitions is achieved once neutral free logic is conceptualized as consisting of two sub-varieties. (shrink)

Names are rigid designators, but what kind of rigidity do they exhibit? Both “obstinately” and “persistently” rigid designators pick out O at every world at which they pick out anything at all. They differ in that obstinately rigid designators also pick out O at worlds at which O fails to exist; persistently rigid designators have no extension whatsoever at worlds at which O fails to exist. The question whether names are obstinate or persistent arises in two contexts: in arguments against (...) rigidified descriptivism (on the grounds that names and rigidified descriptions exhibit different kinds of rigidity) and in considerations about what it means for an expression to be “directly referential.” This paper contends that names are persistent, not obstinate. The position thus clarifies the relationship between Millian theories of names and rigid designation, in addition to undermining attempts to rehabilitate the modal argument against rigidified descriptivism. (shrink)

In this article we will focus our attention on the variety of distributive bisemilattices and some linguistic expansions thereof: bounded, De Morgan, and involutive bisemilattices. After extending Balbes’ representation theorem to bounded, De Morgan, and involutive bisemilattices, we make use of Hartonas–Dunn duality and introduce the categories of 2spaces and 2spaces\. The categories of 2spaces and 2spaces\ will play with respect to the categories of distributive bisemilattices and De Morgan bisemilattices, respectively, a role analogous to the category of Stone spaces (...) with respect to the category of Boolean algebras. Actually, the aim of this work is to show that these categories are, in fact, dually equivalent. (shrink)

McKinsey-style incompatibilist arguments attempt to show that the thesis that subjects have privileged, a priori access to the contents of their thoughts is incompatible with semantic externalism. This incompatibility follows – it is urged – from the fact that these theses jointly entail an absurd conclusion, namely, the possibility of a priori knowledge of the world. In a recent paper I argued that a large and important class of such arguments exemplifies a dialectical failure: if they are valid, the putatively (...) absurd conclusion can be generated without the privileged access premise. Michael McKinsey has responded by arguing that the semantic externalist should adopt a neutral free logic invalidating a principle that my argument essentially relies on. I will say why the semantic commitments of the externalist are in tension with free logic, thereby vindicating my original argument. (shrink)

McKinsey‐style incompatibilist arguments attempt to show that the thesis that subjects have privileged, a priori access to the contents of their thoughts is incompatible with semantic externalism. This incompatibility follows – it is urged – from the fact that these theses jointly entail an absurd conclusion, namely, the possibility of a priori knowledge of the world. In a recent paper I argued that a large and important class of such arguments exemplifies a dialectical failure: if they are valid, the putatively (...) absurd conclusion can be generated without the privileged access premise. Michael McKinsey has responded by arguing that the semantic externalist should adopt a neutral free logic invalidating a principle that my argument essentially relies on. I will say why the semantic commitments of the externalist are in tension with free logic, thereby vindicating my original argument. (shrink)

Frege held that the result of applying a predicate to names lacks reference if any of the names lack reference. We defend the principle against a number of plausible objections. We put forth an account of consequence for a first-order language with identity in which the principle holds.

According to ontological nihilism nothing exists. A recent argument purports to show that this view is indefensible, since its most plausible formulations are tacitly committed to quantificational claims that are inconsistent with the nihilist's view that there aren't any existents. I show that this objection begs the question against the nihilist. The objector's argument relies on an equivalence principle implying that claims which nihilists regard as non-quantificational should nonetheless be interpreted as equivalent to quantified claims, given that both kinds of (...) assertion are assertible in the same contexts. This style of reasoning is supported by considerations of charity, which suggest that similarities in inter-personal patterns of language use provide evidence of similarity in the semantic content of speakers' utterances. However, related considerations also suggest that intra-personal patterns of language use constitute significant semantic evidence of the same kind. When we appreciate this and further recognize that nihilists are disposed to assert the negation of any positive, quantified claim, we see that it is too much to expect principles of semantic interpretation based on considerations of charity to decisively refute nihilism. This result has interesting metametaphysical implications concerning the role and scope of analogous arguments based on principles of interpretive charity. (shrink)

“The confusion of a logical with a real predicate,” according to the Critique of Pure Reason, “is almost beyond correction”. Kant did not assert that existence is no predicate, but that it is only a “logical” one, and not a “real” one. Much the same thing has been said about identity, although Kant himself thought it is real and not logical. We have long lacked a rigorous criterion to distinguish real from logical predicates, and hence have not been able to (...) say why the difference matters. This paper has two objects. First it provides a demarcation between real and logical predicates that confirms Kant's dictum that existence is only “logical.” Secondly it states the theory of a “logical” relation of identity. Perhaps this is not the only identity relation. I show only that once it has been precisely defined in the right setting, there are definite answers to a number of disputed questions about identity. Maybe there are other concepts of identity for which different answers are to be given, but I shall not discuss that disagreeable prospect here. A third application concerns the ontological argument. (shrink)

The paper is a discussion of a result of Hilbert and Bernays in their Grundlagen der Mathemnatik. Their interpretation of the result is similar to the standard intepretation of Tarski's Theorem. This and other interpretations are discussed and shown to be inadequate. Instead, it is argued, the result refutes certain versions of Meinongianism. In addition, it poses new problems for classical logic that are solved by dialetheism.

The hallmark of the deductive systems known as ‘conceptivist’ or ‘containment’ logics is that for all theorems of the form , all atomic formulae appearing in also appear in . Significantly, as a consequence, the principle of Addition fails. While often billed as a formalisation of Kantian analytic judgements, once semantics were discovered for these systems, the approach was largely discounted as merely the imposition of a syntactic filter on unrelated systems. In this paper, we examine a number of prima (...) facie unrelated deductive contexts in which Addition fails and attempt to harmonise them by developing a computational interpretation of conceptivist logics. (shrink)

Partial functions are ubiquitous in both mathematics and computer science. Therefore, it is imperative that the underlying logical formalism for a general-purpose mechanized mathematics system provide strong support for reasoning about partial functions. Unfortunately, the common logical formalisms — first-order logic, type theory, and set theory — are usually only adequate for reasoning about partial functionsin theory. However, the approach to partial functions traditionally employed by mathematicians is quite adequatein practice. This paper shows how the traditional approach to partial functions (...) can be formalized in a range of formalisms that includes first-order logic, simple type theory, and Von-Neumann—Bernays—Gödel set theory. It argues that these new formalisms allow one to directly reason about partial functions; are based on natural, well-understood, familiar principles; and can be effectively implemented in mechanized mathematics systems. (shrink)

Church's simple theory of types is a system of higher-order logic in which functions are assumed to be total. We present in this paper a version of Church's system called PF in which functions may be partial. The semantics of PF, which is based on Henkin's general-models semantics, allows terms to be nondenoting but requires formulas to always denote a standard truth value. We prove that PF is complete with respect to its semantics. The reasoning mechanism in PF for partial (...) functions corresponds closely to mathematical practice, and the formulation of PF adheres tightly to the framework of Church's system. (shrink)

In this paper I present two arguments against the thesis that we experience qualia. I argue that if we experienced qualia then these qualia would have to be essentially vague entities. And I then offer two arguments, one a reworking of Gareth Evans' argument against the possibility of vague objects, the other a reworking of the Sorites argument, to show that no such essentially vague entities can exist. I consider various objections but argue that ultimately they all fail. In particular (...) I claim that the stock responses to the Sorites argument fail against my reworking of the argument because they require us to make a distinction between a determinate reality and how that reality appears to us, whereas in the case of qualia we can make no such distinction. I conclude that there can be no such things as qualia. (shrink)

This article has one aim, to reject the claim that negation is semantically ambiguous. The first section presents the putative incompatibility between truth-value gaps and the truth-schema; the second section presents the motivation for the ambiguity thesis; the third section summarizes arguments against the claim that natural language negation is semantically ambiguous; and the fourth section indicates the problems of an introduction of two distinct negation operators in natural language.

In section III of Pryor 2006a, I argued against the view that the mere fact that a thought- type is hyper-reliable directly gives one justification to believe a thought of that type. A close alternative says that our merely appreciating that the thought-type is hyper-reliable directly gives us that justification.