Kripke has argued that definitions of units of measurements provide examples of statements that are both contingent and a priori. In this paper I argue that definitions of units of measurement are intended to be stipulations of what Kripke calls "theoretical identities": a stipulation that two terms will have the same rigid designation. Hence such a definition is both a priori and necessary. The necessity arises because such definitions appeal to natural kind properties only, which on Kripke's account are necessary.

In this paper I argue that anaphoric pronouns should always be interpreted exhaustively. I propose that pronouns are either used referentially and refer to the speaker's referents of their antecedent indefinites, or descriptively and go proxy for the description recoverable from its antecedent clause. I show how this view can be implemented within a dynamic semantics, and how it can account for various examples that seemed to be problematic for the view that for all unbound pronouns there always should be (...) a notion of exhaustivity/uniqueness involved. The uniqueness assumption for the use of singular pronouns is also shown to be importantto explain what the discourse referents used in dynamic semantics represent. (shrink)

Cet ouvrage de Pascal Engel doit être fortement recommandé pour plusieurs raisons. On est d'abord frappé par l'ampleur du travail accompli et l'étendue du domaine couvert. La documentation est fouillée, l'exposé est clair et un équilibre est toujours maintenu entre les questions générales et les questions de détail. Engel ne perd jamais de vue la perspective d'ensemble qu'il s'est donnée et qui concerne la nature de la logique, y compris lorsqu'il s'emploie à faire certaines nuances ou à proposer une distinction (...) subtile. Il aurait été facile en pareille matière de proposer un mauvais choix de thèmes. Là encore, Engel s'est bien acquitté de sa tâche. On a affaire à un ouvrage dans lequel l'auteur va toujours droit à l'essentiel. Plusieurs sujets sont à peine effleurés, mais cette décision est très souvent heureuse puisqu'elle permet à l'auteur d'établir des liens entre des problématiques qui, de prime abord, semblent très éloignées les unes des autres. L'auteur fait montre d'un étonnant esprit de synthèse et plusieurs thèmes font, à ma connaissance, une première apparition dans la littérature philosophique francophone. Il s'agit donc d'une contribution à la philosophie de la logique qui mérite d'être signalée. On regrettera peut-être la présence d'un assez grand nombre d'erreurs typographiques. Dans la plupart des cas, il ne s'agit que de coquilles mais, dans d'autres cas, elles risquent de nuire à la compréhension du texte surtout lorsqu'elles interviennent dans des formules ou des définitions. (shrink)

In this essay I will defend a novel version of the indexical view on proper names. According to this version, proper names have a relatively sparse truth-conditional meaning that is represented by their rigid content and indexical character, but a relatively rich use-conditional meaning, which I call the (contextual) constraint of a proper name. Firstly, I will provide a brief outline of my favoured indexical view on names in contrast to other indexical views proposed in the relevant literature. Secondly, two (...) general motivations for an indexical view on names will be introduced and defended. Thirdly, I will criticize the two most popular versions of the indexical view on names: formal variable accounts and salience-based formal constant accounts. In the fourth and final section, I will develop my own use-conditional indexical view on names in three different steps by confronting an initial version of this view with three different challenges. (shrink)

By a fragment of a natural language we mean a subset of thatlanguage equipped with semantics which translate its sentences intosome formal system such as first-order logic. The familiar conceptsof satisfiability and entailment can be defined for anysuch fragment in a natural way. The question therefore arises, for anygiven fragment of a natural language, as to the computational complexityof determining satisfiability and entailment within that fragment. Wepresent a series of fragments of English for which the satisfiabilityproblem is polynomial, NP-complete, EXPTIME-complete,NEXPTIME-complete (...) and undecidable. Thus, this paper represents a casestudy in how to approach the problem of determining the logicalcomplexity of various natural language constructions. In addition, wedraw some general conclusions about the relationship between naturallanguage and formal logic. (shrink)

Controlled languages are regimented fragments of natural languagedesigned to make the processing of natural language more efficient andreliable. This paper defines a controlled language, E2V, whose principalgrammatical resources include determiners, relative clauses, reflexivesand pronouns. We provide a formal syntax and semantics for E2V, in whichanaphoric ambiguities are resolved in a linguistically natural way. Weshow that the expressive power of E2V is equal to that of thetwo-variable fragment of first-order logic. It follows that the problemof determining the satisfiability of a set (...) of E2V sentences is NEXPTIMEcomplete. We show that E2V can be extended in various ways withoutcompromising these complexity results; however, relaxing our policy onanaphora resolution renders the satisfiability problem for E2Vundecidable. Finally, we argue that our results have a bearing on thebroader philosophical issue of the relationship between natural andformal languages. (shrink)

Traditional procedures for rational updating fail when it comes to self-locating opinions, such as your credences about where you are and what time it is. This paper develops an updating procedure for rational agents with self-locating beliefs. In short, I argue that rational updating can be factored into two steps. The first step uses information you recall from your previous self to form a hypothetical credence distribution, and the second step changes this hypothetical distribution to reflect information you have genuinely (...) learned as time has passed. While the second step resembles traditional procedures of updating by conditionalization, the first is best understood by analogy to traditional models of how agents transmit self-locating opinions through ordinary interpersonal communication. (shrink)

Greek antiquity saw the development of two distinct systems of logic: Aristotle’s theory of the categorical syllogism and the Stoic theory of the hypothetical syllogism. Some ancient logicians argued that hypothetical syllogistic is more fundamental than categorical syllogistic on the grounds that the latter relies on modes of propositional reasoning such asreductio ad absurdum. Peripatetic logicians, by contrast, sought to establish the priority of categorical over hypothetical syllogistic by reducing various modes of propositional reasoning to categorical form. In the 17th (...) century, this Peripatetic program of reducing hypothetical to categorical logic was championed by Gottfried Wilhelm Leibniz. In an essay titledSpecimina calculi rationalis, Leibniz develops a theory of propositional terms that allows him to derive the rule ofreductio ad absurdumin a purely categorical calculus in which every proposition is of the formA is B. We reconstruct Leibniz’s categorical calculus and show that it is strong enough to establish not only the rule ofreductio ad absurdum, but all the laws of classical propositional logic. Moreover, we show that the propositional logic generated by the nonmonotonic variant of Leibniz’s categorical calculus is a natural system of relevance logic known as RMI$_{{}_ \to ^\neg }$. (shrink)

I provide a novel semantic analysis of proper names and indexicals, combining insights from the competing traditions of referentialism, championed by Kripke and Kaplan, and descriptivism, introduced by Frege and Russell, and more recently resurrected by Geurts and Elbourne, among others. From the referentialist tradition, I borrow the proof that names and indexicals are not synonymous to any definite description but pick their referent from the context directly. From the descriptivist tradition, I take the observation that names, and to some (...) extent indexicals, have uses that are best understood by analogy with anaphora and definite descriptions, that is, following Geurts, in terms of presupposition projection. The hybrid analysis that I propose is couched in Layered Discourse Representation Theory. Proper names and indexicals trigger presuppositions in a dedicated layer, which is semantically interpreted as providing a contextual anchor for the interpretation of the other layers. For the proper resolution of DRSs with layered presuppositions, I add two constraints to van der Sandt's algorithm. The resulting proposal accounts for both the classic philosophical examples and the new linguistic data, preserving a unified account of the preferred rigid interpretation of both names and indexicals, while leaving room for non-referential readings under contextual pressure. (shrink)

ABSTRACT I suggest how a broadly Kantian critique of classical logic might spring from reflections on constructibility conditions. According to Kant, mathematics is concerned with objects that are given through ‘arbitrary synthesis,’ in the form of ‘constructions of concepts’ in the medium of ‘pure intuition.’ Logic, by contrast, is narrowly constrained – it has no objects of its own and is fixed by the very forms of thought. That is why there is not much room for developments within logic, as (...) compared to the progress in mathematics. Kant’s view of logic remains critical, though – through considerations that are effectively on the scope and limits of classical logic and which play a part in his transcendental idealism. The most important ones are to be found in his critique of the use of reductio ad absurdum proofs in metaphysics and his solutions to the ‘antinomies of pure reason.’ Arguably, these considerations carry over to mathematics as well – by way of ‘analogues’ to the antinomies – in particular in resolving infinity paradoxes. (shrink)

The later Wittgenstein famously holds that an understanding which tries to run up against the limits of language bumps itself and results in nothing but plain nonsense. Therefore, the task of philosophy cannot be to create an ‘ideal’ language so as to produce a ‘real’ understanding for the first time; its aim must be to remove particular misunderstandings by clarifying the use of our ordinary language. Accordingly, Wittgenstein opposes both the sublime terms of traditional philosophy and the formal frameworks of (...) modern logics—and adheres to a pointedly casual, colloquial style in his own philosophizing. However, there seems to lurk a certain inconsistency in Wittgenstein’s ordinary language approach: his philosophical remarks frequently remain enigmatic, and many of the terms Wittgenstein coins seem to be highly technical. Thus, one might wonder whether his verdicts on the limits of language and on philosophical jargons might not be turned against his own practice. The present essay probes the extent to which the contravening tendencies in Wittgenstein’s mature philosophy might be reconciled. Section 2 sketches Wittgenstein’s general approach to philosophy and tracks the special rôle that the language of everyday life occupies therein. Section 3 reconstructs Wittgenstein’s preferred method for philosophy, which he calls perspicuous representation, and argues that this method implements an aesthetic conception of philosophy and a poetic approach to philosophical language, in which philosophical insights are not explicitly stated, but mediated through well-worded and creatively composed descriptions. Section 4 discusses how Wittgenstein’s philosophical poetics relates to artificial terminologies and grammars in philosophy and science. (shrink)

Few philosophers believe in the existence of so-called negative properties. Indeed, many find it mind-boggling just to imagine such entities. By contrast, I believe not only that negative properties are quite conceivable, but also that there are good reasons for thinking that some such properties actually exist. In this paper, I would like to explicate a concept of negative properties which I think avoids the logical absurdities commonly believed to frustrate theories of negative existences. To do this, I shall deploy (...) a conceptual approach to ontology: I first evaluate the ontological commitments of ordinary negative statements, before I argue that, from the perspective of conceptual analysis, negative properties are no more suspicious than positive properties. In the second part of this paper, I probe the extent to which one can explain the distinction between positive and negative properties in terms of facts about logico-semantical entailment. (shrink)

The theory of frames has recently been proposed as a universal format for knowledge representation in language, cognition and science. Frames represent categories as well as individual objects and events in terms of recursive attribute-value structures. In this paper, we would like to explore the potential ontological commitments of frame-based knowledge representations, with particular emphasis on the ontological status of the possessors of quality attributes in individual object frames. While not strictly incompatible with nominalistic, bundle- or substratum-theoretic approaches to the (...) metaphysics of particular objects, it will be argued that representing objects in terms of attribute-value structures is more in accordance with a tradition that can be traced back to Aristotle’s doctrine of physical substances. Attributes appear to describe primary potentialities of objects, which, in the Aristotelian view, are the unchangeable nature or essence, hence substance, of any separate object. (shrink)

Bare conditionals, I argue, exhibit Conditional Duality in that when they appear in downward entailing environments they differ from bare conditionals elsewhere in having existential rather than universal force. Two recalcitrant phenomena are shown to find a new explanation under this thesis: bare conditionals under only, and bare conditionals in the scope of negative nominal quantifiers, or what has come to be known as Higginbotham’s puzzle. I also consider how bare conditionals behave when embedded under negation, arguing that such conditionals (...) often involve denial negation. One important conclusion that emerges from the discussion is that an account of bare conditionals that validates Conditional Excluded Middle is not warranted. By limiting the scope of the strict analysis Conditional Duality is also a way of maintaining such an account. (shrink)

Contemporary philosophical logic rests on a distinction between things and properties. Properties are thought to differ from things in that their proper expression is incomplete or unsaturated. In this paper, I will argue that Aristotle did not distinguish between things and properties in this way. I will show, first, that Aristotle’s essences are not properties, and that certain passages in Aristotle make sense only if we do not take accidents to be properties either. The notion of a property is thus (...) not fundamental in Aristotle’s theory of predication. Aristotle’s predicate terms do not stand for properties but for non-substantial things. Second, I will explain and explore the distinction between substances and non-substantial things. This will yield a viable alternative to our contemporary, Fregean account of predication. (shrink)

I argue that a tripartite analysis of simple statements such as “Bucephalus is a horse”, according to which they divide into two terms and a copula, requires the notion of a repeatable: something such that more than one particular can literally be it. I pose a familiar dilemma with respect to repeatables, and turn to Avicenna for a solution, who discusses a similar dilemma concerning quiddities. I conclude by describing how Avicenna’s quiddities relate to repeatables, and how both quiddities and (...) repeatables may contribute to a tripartite analysis of predication. (shrink)

In the late nineteenth century there were two very active lines of research in the field of formal logic. First, logicians (mostly in English-speaking countries) were engaged in formulating a generally traditional logic as an algebra, a part of mathematics; second, logicians (mostly on the continent) were busy building a non-traditional logic that could serve, not as a part of, but as the foundation of, mathematics. By the end of the First World War the former line had been pretty well (...) abandoned while the second continued to expand. However, that old abandoned line, stretching from Aristotle, through the Scholastics and then Leibniz to the nineteenth century algebraists, had not been completely forgotten. One of those logicians who has recently worked on the restoration (and, importantly, the extension) of that line is Fred Sommers. His Term Logic preserves a number of traditional insights (especially involving the theory of logical syntax), while also enjoying a power to account for formal inference at least comparable to that of the standard logic now in place. (shrink)

This paper argues for a version of metalinguistic descriptivism, the Mill-Frege view, comparing it to a currently popular alternative, predicativism. The Mill-Frege view combines tenets of Fregean views with features of the theory of direct reference. According to it, proper names have metalinguistic senses, known by competent speakers on the basis of their competence, which figure in ancillary presuppositions. In support of the view the paper argues that the name-bearing relation—which predicativists cite to account for the properties that they take (...) names to express—depends on acts of naming with a semantic significance. Acts of naming create particular words specifically designed for referential use, which they perform whether or not the language has other words articulated with the same sound or orthography. Like other forms of metalinguistic descriptivism, the Mill-Frege view affords responses to Kripke’s semantic and epistemic arguments against descriptivism. The view is prima facie more complex than predicativism; but the additional complexity is independently attested in natural languages and well-motivated. Finally, the Mill-Frege proposal deals well with Kripke’s modal argument, and accounts for modal intuitions about names, both issues that pose serious trouble to predicativism. (shrink)

This paper formalizes part of the cognitive architecture that Kant develops in the Critique of Pure Reason. The central Kantian notion that we formalize is the rule. As we interpret Kant, a rule is not a declarative conditional stating what would be true if such and such conditions hold. Rather, a Kantian rule is a general procedure, represented by a conditional imperative or permissive, indicating which acts must or may be performed, given certain acts that are already being performed. These (...) acts are not propositions; they do not have truth-values. Our formalization is related to the input/ output logics, a family of logics designed to capture relations between elements that need not have truth-values. In this paper, we introduce KL3 as a formalization of Kant’s conception of rules as conditional imperatives and permissives. We explain how it differs from standard input/output logics, geometric logic, and first-order logic, as well as how it translates natural language sentences not well captured by first-order logic. Finally, we show how the various distinctions in Kant’s much-maligned Table of Judgements emerge as the most natural way of dividing up the various types and sub-types of rule in KL3. Our analysis sheds new light on the way in which normative notions play a fundamental role in the conception of logic at the heart of Kant’s theoretical philosophy. (shrink)

Les travaux de Fred Sommers dans le domaine de l'ontologie ont été l'objet, jusqu'à présent, de beaucoup moins d'attention critique qu'ils ne sont aptes à en susciter. C'est au cours des années soixante que Sommers a élaboré sa théorie et qu'il l'a rendue publique par le moyen d'une série d'articles et de conférences. Bien que ses travaux aient alors fait l'objet de quelques critiques ou commentaires, ils ont, depuis, généralement été passés sous silence. Récemment, la revue Monist a fait paraître (...) un numéro spécial entièrement consacré au thème des catégories. Considérant le thème, l'importance et la qualité des articles regroupés dans ce numéro, il est surprenant de constater que les idées hautement originales et suggestives de Sommers ne soient mentionnées par aucun des auteurs. Evidemment, une des raisons pour lesquelles les idées de Sommers suscitent présentement si peu d'intérêt est le fait que, depuis la fin des années soixante, il a lui-même laissé de côté l'ontologie pour se tourner vers la logique—un domaine où il a fait et fait toujours couler beaucoup d'encre. (shrink)

Fred Sommers passed away in October of 2014 in his 92nd year. Having begun his teaching at Columbia University, he eventually became the Harry A. Wolfson Chair in Philosophy at Brandeis University, where he taught from 1963 to 1993. During his long and productive career, Sommers authored or co-authored over 50 books, articles, reviews, etc., presenting his ideas on numerous occasions throughout North America and Europe. His work was characterized by a commitment to the preservation and application of historical insights (...) and to the value of a well-articulated, coherent logical system. He was recognized for his independence and refusal to accept any view on the basis of authority alone. This made him a formidable critic but accounted in part for his many innovative and original ideas. In spite of his general contrariness in logic, Sommers earned the respect of the majority of his contemporaries, including Russell, Quine, van Benthem, Hacking, Suppes, and Strawson. In 2005, he was the subjec... (shrink)

It is commonly accepted, after Frege, that identity statements like “Tully is Cicero” differ from statements like “Tully is Tully”. For the former, unlike the latter, are informative. One way to deal with the information problem is to postulate that the terms ‘Tully’ and ‘Cicero’ come equipped with different informative values. Another approach is to claim that statements like these are of the subject/predicate form. As such, they should be analyzed along the way we treat “Tully walks”. Since proper names (...) can appear in predicative position we could go as far as to dismiss the sign of identity altogether, some told us. I will try to discuss the advantages and/or disadvantages of this approach and investigate whether Frege’s view that the ‘is’ of identity must be distinguished from the ‘is’ of predication can be reconciled with the fact that names can appear in predicative position. (shrink)

En esta contribución proponemos una representación de un fragmento de la silogística estadística de Thompson usando la lógica de términos de Sommers. El resultado es una interpretación terminista de la silogística estadística.

Given some links between Lyndon’s Interpolation Theorem, term distribution, and Sommers and Englebretsen’s logic, in this contribution we attempt to capture a sense of interpolation for Sommers and Englebretsen’s Term Functor Logic. In order to reach this goal we first expound the basics of Term Functor Logic, together with a sense of term distribution, and then we offer a proof of our main contribution.

Resumen En esta contribución ofrecemos una interpretación del pons asinorum que se basa en una lógica de términos contemporánea. Esto nos permite revitalizar la idea del pons asinorum para generar el -políticamente correcto- pons scholasticorum, una versión terminística del pons asinorum que conecta la inventio medii con el dictum de omni et nullo.In this contribution we offer an interpretation of the pons asinorum by using a contemporary term logic. This interpretation allows us to revitalize the concept of the pons asinorum (...) in order to produce the -politically correct- pons scholasticorum, a terministic version of the pons asinorum that relates the inventio medii with the dictum de omni et nullo. (shrink)

This book serves as a concise introduction to some main topics in modern formal logic for undergraduates who already have some familiarity with formal languages. There are chapters on sentential and quantificational logic, modal logic, elementary set theory, a brief introduction to the incompleteness theorem, and a modern development of traditional Aristotelian Logic.

This paper presents a version of analytical Thomism that brings the principles of Aquinas into systematic and sustained contact with the sciences as opposed to contemporary philosophy. The leading idea of this version of analytical Thomism is to test the viability of scholastic principles by seeing if they provide the resources to cope with problems emerging from the natural and social sciences. If they do, then Thomism vindicates itself in the marketplace of ideas. If not, then the analytical Thomist knows (...) where the perennial philosophy needs further development and perhaps revision. The first part of the paper sets out the rationale for this project. The remainder of the paper illustrates this approach by examining a problem emerging from evolutionary biology, namely, the provision of a theory of individuation for living entities. (shrink)

There is a clash between some people's positive logical intuitions about traditional or Aristotelian logic and the assessment ofthat logic made by modem logic. In response to the clash, four sorts of reasons that might be given for referring one logic to the other are considered, but it is argued that none of them provides a decisive reason in favor of one rather than the other. A reformist and a radical response to the apparent inability to give reasons to prefer (...) one logic to the other are considered and reasons given for preferring the radical response. (shrink)

We give a condensed survey of recent research on generalized quantifiers in logic, linguistics and computer science, under the following headings: Logical definability and expressive power, Polyadic quantifiers and linguistic definability, Weak semantics and axiomatizability, Computational semantics, Quantifiers in dynamic settings, Quantifiers and modal logic, Proof theory of generalized quantifiers.

This is an attempt at reviving Kneale's version of the description theory of names, which says that a proper name is synonymous with a definite description of the form ‘the individual named so-and-so’. To begin with, I adduce a wide range of observations to show that names and overt definites are alike in all relevant respects. I then turn to Kripke's main objection against Kneale's proposal, and endeavour to refute it. In the remainder of the paper I elaborate on Kneale's (...) analysis, adopting a theory of presupposition proposed by van der Sandt. (shrink)

A system of categories is a complete list of highest kinds or genera. Traditionally, following Aristotle, these have been thought of as highest genera of entities (in the widest sense of the term), so that a system of categories undertaken in this realist spirit would ideally provide an inventory of everything there is, thus answering the most basic of metaphysical questions: “What is there?”. Skepticism about the possibilities for discerning the different categories of ‘reality itself’ has led others to approach (...) category systems not with the aim of cataloging the highest kinds in the world itself, but rather with the aim of elucidating the categories of our conceptual system. Thus Kant makes the shift to a conceptualist approach by drawing out the categories that are.. (shrink)

We discuss presupposition, the phenomenon whereby speakers mark linguistically the information that is presupposed or taken for granted, rather than being part of the main propositional content of a speech act. Expressions and constructions carrying presuppositions are called “presupposition triggers”, forming a large class including definites and factive verbs. The article first introduces the range of triggers, the basic properties of presuppositions such as projection and cancellability, and the diagnostic tests used to identify them. The reader is then introducedto major (...) models of presupposition from the last 50 years, separated into three classes: Frege-Strawson derived semantic models, pragmaticmodels such as that offered by Stalnaker, and dynamic models. Finallywe discuss some of the main current issues in presupposition theory. These involve accommodation, which occurs when a hearer's knowledge state is adjusted to meet the speaker's presuppositions; presupposition failure, which occurs when a presupposition is false; the interaction between presuppositions and attitudes; and the triggering problem, i.e., the problem of explaining why presuppositions occur in the first place. (shrink)

1 Logic in philosophy The century that was Logic has played an important role in modern philosophy, especially, in alliances with philosophical schools such as the Vienna Circle, neopositivism, or formal language variants of analytical philosophy. The original impact was via the work of Frege, Russell, and other pioneers, backed up by the prestige of research into the foundations of mathematics, which was fast bringing to light those amazing insights that still impress us to-day. The Golden Age of the 1930s (...) deeply affected philosophy, and heartened the minority of philosophers with a formalanalytical bent. As Brand Blanshard writes in Reason and Analysis (1964) – I quote from memory here, to avoid the usual disappointment when re-reading an original text. (shrink)

This paper is a brief history of natural logic at the interface of logic, linguistics, and nowadays also other disciplines. It merely summarizes some facts that deserve to be common knowledge.

Logic has its roots in the study of valid argument, but while traditional logicians worked with natural language directly, modern approaches first translate natural arguments into an artificial language. The reason for this step is that some artificial languages now have very well developed inferential systems. There is no doubt that this is a great advantage in general, but for the study of natural reasoning it is a drawback that the original linguistic forms get lost in translation. An alternative approach (...) would be to develop a general theory of the natural logic behind human reasoning and human information processing by studying formal logics that operate directly on linguistic representations. That this is possible we will try to make plausible in this paper. It will turn out that one level of representation, that of Logical Form, can meaningfully be identified with the language of an existing and well-understood logic, a restricted form of the theory of types. It is not difficult to devise inference systems for this language, and it is thus possible to study reasoning systems that are based directly on language. (shrink)