Providing a principled characterization of the distinction between logical and non-logical expressions is a longstanding issue in the philosophy of logic. In the Logical Syntax of Language, Carnap proposes a syntactic solution to this problem, which aims at grounding the claim that logic and mathematics are analytic. Roughly speaking, his idea is that logic and mathematics correspond to the largest part of science for which it is possible to completely specify by "syntactic" means which sentences are valid and which are (...) not. Despite a renewed interest in the philosophical benefits of analyticity, both inside and outside of Carnap scholarship, Carnap's definition of logical expressions seems to have drawn too little attention. I shall argue that it is worth a second look. More precisely, my aim will be to defend this idea against some technical problems faced by Carnap's way of implementing it and against Quinean attacks on syntax-based conventionalism. Section 1 presents Carnap's definition in the context of Logical Syntax of Language, that is, how exactly the definition works, and why Carnap needs it. In section 2, I review three challenges that have been raised in the literature, and I propose to revise the definition accordingly. I argue that its modified version is immune to the previous challenges, and, to some extent, immune to new challenges as well. In the last section, I suggest that the definition has a philosophical interest of its own, because standard Quinean objections are not as conclusive as one might think when attention is paid to the fact that Carnap requires complete syntactic specification of validities. (shrink)

This paper is divided into four sections. -/- The first section contains an informal characterization of what may, for the purposes of this discussion, be referred to as the standard interpretation of theological statements. -/- Then, in the second section, I mention two challenges to the commonsense view that theological statements have cognitive content: the quote “falsifiability challenge” and the “ translatability challenge”. -/- Both of these challenges involve an appeal to an empiricist criterion of cognitive content, but I (...) contend that they are nonetheless very different arguments and that clarity about the fundamental issues involved in the question of theology and verificationism cannot be achieved unless these two lines are argument are carefully distinguished. -/- The third section is concerned with the question of the possibility of an empiricist criterion of cognitive significance. The underlying purpose of the discussion will be to arrive derive at an evaluation of the commonly advanced claim that verificationist objections to the meaningfulness of theological language can be refuted by simply arguing that is not possible to formulate an adequate confirmability criterion of cognitive significance. -/- I then conclude by suggesting some responses that seem more promising. (shrink)

Permutation invariance is often presented as the correct criterion for logicality. The basic idea is that one can demarcate the realm of logic by isolating specific entities—logical notions or constants—and that permutation invariance would provide a philosophically motivated and technically sophisticated criterion for what counts as a logical notion. The thesis of permutation invariance as a criterion for logicality has received considerable attention in the literature in recent decades, and much of the debate is developed (...) against the background of ideas put forth by Tarski in a 1966 lecture (Tarski 1966/1986). But as noted by Tarski himself in the lecture, the permutation invariance criterion yields a class of putative ‘logical constants’ that are essentially only sensitive to the number of elements in classes of individuals. Thus, to hold the permutation invariance thesis essentially amounts to limiting the scope of logic to quantificational phenomena, which is controversial at best and possibly simply wrong. In this paper, I argue that permutation invariance is a misguided approach to the nature of logic because it is not an adequate formal explanans for the informal notion of the generality of logic. In particular, I discuss some cases of undergeneration of the criterion, i.e. the fact that it excludes from the realm of logic operators that we have good reason to regard as logical, especially some modal operators. (shrink)

The Fifth International Congress of Logic, Methodology and Philosophy of Science was held at the University of Western Ontario, London, Canada, 27 August to 2 September 1975. The Congress was held under the auspices of the International Union of History and Philosophy of Science, Division of Logic, Methodology and Philosophy of Science, and was sponsored by the National Research Council of Canada and the University of Western Ontario. As those associated closely with the work of the Division over the years (...) know well, the work undertaken by its members varies greatly and spans a number of fields not always obviously related. In addition, the volume of work done by first rate scholars and scientists in the various fields of the Division has risen enormously. For these and related reasons it seemed to the editors chosen by the Divisional officers that the usual format of publishing the proceedings of the Congress be abandoned in favour of a somewhat more flexible, and hopefully acceptable, method of pre sentation. Accordingly, the work of the invited participants to the Congress has been divided into four volumes appearing in the University of Western Ontario Series in Philosophy of Science. The volumes are entitled, Logic, Foundations of Mathematics and Computability Theory, Foun dational Problems in the Special Sciences, Basic Problems in Methodol ogy and Linguistics, and Historical and Philosophical Dimensions of Logic, Methodology and Philosophy of Science. (shrink)

I propose an argument for the thesis that laws of nature are necessary in the sense of holding in all worlds sharing the properties of the actual world, on the basis of a principle I propose to call the Causal Criterion of Reality . The CCR says: for an entity to be real it is necessary and sufficient that it is capable to make a difference to causal interactions. The crucial idea here is that the capacity to interact causally (...) - or to contribute to determining causal interactions - is not only the ultimate metaphysical ground for the existence of an entity, but it also provides a criterion for determining the nature of that entity, i.e. its properties. The alternative is to conceive of laws of nature as contingent: they could be different from what they are like in the actual world, where that possibility is understood to be metaphysical, not only epistemic. For the sake of this paper, I shall accept Armstrong's thesis that laws of nature are relations between universals. I also follow Armstrong in the view that both the existence and the properties of particulars are metaphysically independent of the existence and identity of other particular. However, what is controversial and what I shall challenge is his thesis that universals are like particulars in the following respect: according to Armstrong, each universal is a logically distinct entity whose existence and identity is independent of the existence and identity of other universals. My aim in this paper is to show that the identity of a universal is entirely determined by its lawful relations to other universals. The crucial premise I use is the thesis that the CCR is a universal criterion, which applies both to particulars and universals. From the thesis that the identity of a universal is exclusively determined by laws, it follows that laws are necessary in the sense that they cannot differ without the universals they link also being different. This creates a difficulty for those authors who, as Armstrong, accept the CCR but nevertheless defend the view that laws are contingent. (shrink)

A semantics for logical necessity, based on Carnap's criterion of adequacy, is given with respect to the ontology of logical atomism. A calculus for sentential (propositional) modal logic is described and shown to be complete with respect to this semantics. The semantics is then modified in terms of a restricted notion of 'all possible worlds' in the interpretation of necessity and shown to yield a completeness theorem for the modal logic S5. Such a restricted notion introduces material content into (...) the meaning of necessity so that, in addition to atomic facts, there are "modal facts" that distinguish one world from another. (shrink)

1 Meaning and Truth Objection to propositions Propositions as information Diffuseness of empirical meaning Propositions dismissed Truth and semantic ascent Tokens and eternal sentences 2 Grammar Grammar by recursion Categories Immanence and transcendence Grammarian's goal reexamined Logical grammar Redundant devices Names and functors Lexicon, particle, and name Criterion of lexicon Time, events, adverbs Attitudes and modality 3 Truth Truth and satisfaction Satisfaction by sequences Tarski's definition of truth Paradox in the object language Resolution in set theory 4 Logical Truth (...) In terms of structure In terms of substitution In terms of models Adequacy of substituteon In terms of proof In terms of grammar 5 The Scope of Logic Affinities of identity Identity reduced Set theory Set theory in sheep's clothing Logic in wolf's clothing Scope of the virtual theory Simulated class quantification Other simulated quantification Annexes 6 Deviant Login Change of logic, change of subject Logic in translation Law of excluded middle Debate about the dichotomy Intuitionism Branched quantifiers Substitutional quantification Its strength 7 The Ground of Logical Truth The semblance of a theory An untenable dualism The place of logic For Further Reading Index. (shrink)

The waning popularity of logical empiricism and the supposed discovery of insurmountable technical difficulties led most philosophers to abandon the project to formulate a formal criterion of empirical significance. Such a criterion would delineate claims that observation can confirm or disconfirm from those it cannot. Although early criteria were clearly inadequate, criticisms made of later, more sophisticated criteria were often indefensible or easily answered. Most importantly, Carnap’s last criterion was seriously misinterpreted and an amended version of it (...) remains tenable. (shrink)

The Bounds of Logic presents a new philosophical theory of the scope and nature of logic based on critical analysis of the principles underlying modern Tarskian logic and inspired by mathematical and linguistic development. Extracting central philosophical ideas from Tarski’s early work in semantics, Sher questions whether these are fully realized by the standard first-order system. The answer lays the foundation for a new, broader conception of logic. By generally characterizing logical terms, Sher establishes a fundamental result in semantics. Her (...) development of the notion of logicality for quantifiers and her work on branching are of great importance for linguistics. Sher outlines the boundaries of the new logic and points out some of the philosophical ramifications of the new view of logic for such issues as the logicist thesis, ontological commitment, the role of mathematics in logic, and the metaphysical underpinning of logic. She proposes a constructive definition of logical terms, reexamines and extends the notion of branching quantification, and discusses various linguistic issues and applications. (shrink)

Effort is then well-nigh indescribable. Not wholly so, else it would be meaningless. Description is a matter of degree: who can fully describe red or wet? To be sure, description comes down in the end to the pointing to certain given qualities or relations or events which are just there. All connotation rests on denotation, though it may be something more. But the unique positive thing about effort is its originality; to which indeed we can point, since every one experiences (...) it in himself. Yet common to all men though it is, it is so intangible! more spirit than body, more force than substance. We should perhaps best call it not a datum but a factum, or better still, a fiat, a doing rather than a deed, yet not merely a becoming, for we see things coming to be, we hear a melody progressing and touch a moving object. Effort, dynamic as it is, is not just the process, rather it is--we must re-iterate--the start, the initiative of the process. Nor is the experience of it properly called mystical. Even if mystical experience were indescribable, as has been wrongly alleged, these would be two quite different indescribables, the one receptive, the other originative. All we can say perhaps is that effort is analogous to the push that starts the ball rolling, not the motion of the ball, not the acceleration, but the enforcement of these. Its witness does not lie in its value as explanation of the motion; the witness is direct, the immediate experience which every man has. It seems to be no object of scientific investigation in the technical sense. It cannot be measured by itself, as acceleration and motion are measured. That is why physics has abandoned the old notion of force, the physical analogue of effort, replacing it by mass-acceleration. That is why the rationalists in modern philosophy look askance at this direct experience of man, so intangible that we can draw from it no logical implications. For it has no structure. Its characteristic is not clearness nor distinctness. We might be tempted to say it is like a point in space, too small to be envisaged, yet not a zero; but it is more like a dot or spark, so small as to be just seen, so small as to have no visible spread, no content that we can analyze to draw out rational consequences connecting it with other things. Here too we see why the contemplative thinker seldom believes in free choice, which the natural man naturally accepts. Free choice is the kind of thing that might well belong to this experience; free choice is origination. Not necessarily that all effort is freely made. The baby exercises no free choice when he sucks hard at the nipple, nor the adult when he wrestles for his life with an enemy. But they want, need, desire; that is the point. Desire--that is the essence of effort. Desire has the originative quality; it comes as it were out of one's self and from no other source, it is what we want, our self insisting on its own. But the business is so deep within that it is easily overlooked, or deliberately excluded from the gaze, and without a qualm. We might say it is too near to be noticed, or too deep down to obtrude itself, as the water in the well is easy to see, but not the spring at the bottom of the well. Effort disappears from the scene when the thinker is calmly gazing; but when he acts it is felt, and strongly felt. It is in fact the very essence of the self, the well-spring of its worth and its growth. A man is what he does. His worth lies in what he makes. All that he is responsible for, all that he earns, is credited with, or guilty of, comes from this innermost source. So thinks the practical man, so we all believe when we are conducting our lives in intercourse with one another and with nature. But for the contemplative attitude there is here too little of clear articulation, of object-matter for analysis; no use can be made of it in a deductive system. So the system-builders discard it. (shrink)

We investigate a recently devised polyhedral semantics for intermediate logics, in which formulas are interpreted in n-dimensional polyhedra. An intermediate logic is polyhedrally complete if it is complete with respect to some class of polyhedra. The first main result of this paper is a necessary and sufficient condition for the polyhedral completeness of a logic. This condition, which we call the Nerve Criterion, is expressed in terms of Alexandrov’s notion of the nerve of a poset. It affords a purely (...) combinatorial characterisation of polyhedrally complete logics. Using the Nerve Criterion we show, easily, that there are continuum many intermediate logics that are not polyhedrally complete but which have the finite model property. We also provide, at considerable combinatorial labour, a countably infinite class of logics axiomatised by the Jankov–Fine formulas of ‘starlike trees’ all of which are polyhedrally complete. The polyhedral completeness theorem for these ‘starlike logics’ is the second main result of this paper. (shrink)

European Journal of Philosophy, EarlyView.

The essay discusses a recurrent criticism of the isomorphism-invariance criterion for logical terms, according to which the criterion pertains only to the extension of logical terms, and neglects the meaning, or the way the extension is fixed. A term, so claim the critics, can be invariant under isomorphisms and yet involve a contingent or a posteriori component in its meaning, thus compromising the necessity or apriority of logical truth and logical consequence. This essay shows that the arguments underlying (...) the criticism are flawed since they rely on an invalid inference from the modal or epistemic status of statements in the metalanguage to that of statements in the object-language. The essay focuses on McCarthy’s version of the argument, but refers to Hanson and McGee’s versions as well. (shrink)

This article considers the development of Philipp Frank’s opposition to metaphysics in the light of the contention that there also was a long-standing pragmatic strand to the theorizing about science in the Vienna Circle. It is argued that the later Frank did not only distinguish metaphysical statements from those deemed simply cognitively meaningless by a substantive criterion but that in order to identify the latter he also sought to employ a practical rather than a formal criterion with which (...) he and Neurath had long been acquainted. (shrink)

The meaning of scientific propositions is not always expressible in terms of observable phenomena. Such propositions involve generalizations, and also terms that are theoretical constructs. I study here how to assess the meaning of scientific propositions, that is, the specific import of theoretical terms. Empiricists have expressed a concern that scientific propositions, and theoretical terms, should always be, to some degree, related to observable consequences. We can see that the former empiricist criterion of meaning only implies for theoretical terms (...) not to be definable in terms of observable, but that their use put a constraint on the observable consequences of a theory. To that effect, Ramsey's method of formal elimination of theoretical terms can be an interesting tool. It has faced important logical objections, which have mostly been addressed with respect to the problem of the ontological commitment of the second-order quantification they imply. I show here that these criticisms can be overcome, and that there can be a successful Ramsey elimination of theoretical terms with first order sentences, making Ramsey's method a relevant tool to assess the empirical meaning of scientific propositions. (shrink)

The failed criterion of logical truth proposed by Carnap in the Logical Syntax of Language was based on the determinateness of all logical and mathematical statements. It is related to a conception which is independent of the specifics of the system of the Syntax, hints of which occur elsewhere in Carnap’s writings, and those of others. What is essential is the idea that the logical terms are invariant under reinterpretation of the empirical terms, and are therefore semantically determinate. A (...) certain objection to Carnap’s version of the invariance conception has been repeated several times in the literature. It is based on Gödel incompleteness, which is puzzling, since Carnap’s Syntax is otherwise quite careful to take account of Gödel. We show here that, in fact, the objection is invalid and is based on a confusion about determinacy. Sorting this out is worthwhile not only for the purpose of better understanding Carnap’s thinking in the Syntax, though. The invariance conception is also related to recent work in the philosophy of logic regarding “logicality”—the characterization of logical concepts—following a proposal of Tarski’s. It is even connected to some very recent developments in the foundations of mathematics. (shrink)

The book discusses the central notion of logic: the concept of logical consequence. It shows that the classical definition of consequence as truth preservation in all models must be restricted to all admissible models. The challenge for the philosophy of logic is therefore to supplement the definition with a criterion for admissible models. -/- The problem of logical constants, so prominent in the current debate, constitutes but a special case of this much more general demarcation problem. The book explores (...) the various dimensions of the problem of admissible models and argues that standard responses are unwarranted. As a result, it develops a new vision of logic, suggesting in particular that logic is deeply imbued with metaphysics. (shrink)

Throughout his whole work, Wittgenstein seizes on a distinction between logical and physical possibility, and impossibility. Despite this continuity and although, Wittgenstein brings in this distinction in various contexts and from different vantage points, he often solely brushes over it without elaborating in detail. In the so-called Big Typescript, however, he dedicates himself not only to the distinction between logical and physical possibility but also to the distinction between logical possibility and impossibility in particular investigations. In the course of these (...) investigations, another aspect arises and is tossed and turned repeatedly by Wittgenstein – namely, the place of “imaginability” in these considerations. On the basis of three focussed chapters in the Big Typescript, I argue that “imaginability” as an utterance of the form “being able to imagine ‘what it would be like’” can be allocated the place of a criterion for logical possibility. To this end, I will first outline the chapters 96., 27. and 26. in one section each. Although in these chapters, Wittgenstein only indicates rather than claiming explicitly “imaginability” to be a criterion for logical possibility, I will discuss in the last section how this conclusion can be drawn by combining the results of the previous sections. (shrink)

There is now a well-established distinction recognized in the ways simplicity considerations enter into science. Laws of nature may be graded either with regard to their simplicity of form or with regard to the fewness of the concepts employed to express them. I shall distinguish these as formal simplicity and conceptual simplicity respectively. Dr. J. O. Wisdom suggests that it should be fewness of non-instantial concepts that serves as the guide for making judgements of relative simplicity; a “non-instantial” concept being (...) a concept which is constructed for the purpose of theory, its meaning not being derived simply from experience. Hence non-instantial concepts are, from a logical point of view, to be contrasted with the concepts used to express and record observations directly, that is with instantial concepts representing observables. This seems to be too narrow a restriction on the reduction of concepts. Clearly an advance towards simplicity has been made not only when e.g. a non-instantial concept like “force of gravity” is eliminated from our technical language, but also when the number of instantial concepts is reduced by redefinition, in terms of a smaller number of observables. For example a great simplification was surely made when space-traversed, time taken and mass were chosen as the dynamic “simples”, for the multiplicity of kinds of motion were found to be expressible as functions of these concepts. “Motion” is not non-instantial in the same way as “force of gravity” or “kinetic energy” is non-instantial. However, once this extension to instantial concepts is made there is no need to quarrel with the form/concept distinction as marking a pritma facie difference in criteria of some methodological importance; for a choice say to concentrate on using the fewest concepts does, and one would be inclined to think must , lead to a “decrease” in the formal simplicity of the laws of nature. (shrink)

The fundamental tenet of modern empiricism is the view that all non-analytic knowledge is based on experience. Let us call this thesis the principle of empiricism. [1] Contemporary logical empiricism has added [2] to it the maxim that a sentence makes a cognitively meaningful assertion, and thus can be said to be either true or false, only if it is either (1) analytic or self-contradictory or (2) capable, at least in principle, of experiential test. According to this so-called empiricist (...) class='Hi'>criterion of cognitive meaning, or of cognitive significance, many of the formulations of traditional metaphysics and large parts of epistemology are devoid of cognitive significance--however rich some of them may be in non-cognitive import by virtue of their emotive appeal or the moral inspiration they offer. Similarly certain doctrines which have been, at one time or another, formulated within empirical science or its border disciplines are so contrived as to be incapable of test by any conceivable evidence; they are therefore qualified as pseudo- [p. 42:] hypotheses, which assert nothing, and which therefore have no explanatory or predictive force whatever. This verdict applies, for example, to the neo-vitalist speculations about entelechies or vital forces, and to the "telefinalist hypothesis" propounded by Lecomte du Noüy. (shrink)

According to the classical invariance criterion, a term is logical if and only if its extension is isomorphism-invariant. However, a number of authors have devised examples that challenge the sufficiency of this condition: accepting these examples as logical constants would introduce objectionable contingent elements into logic. Recently, Gil Sagi has responded that these objections are based on a fallacious inference from the modal status of a sentence to the modal status of the proposition expressed by that sentence. The present (...) paper demonstrates that Sagi’s response, though successful, is futile. There is another objection, based on the same type of example, that is not susceptible to Sagi’s criticism: accepting the examples as logical terms would have the fatal consequence that any contingent metalanguage sentence is entailed by the truth of some logically true object-language sentence. I conclude with a sketch of an alternative to the classical invariance criterion. (shrink)

The paper provides a new argument against the classical invariance criterion for logical terms: if all terms with a permutation invariant extension qualify as logical, then for any arbitrary true contingent sentence K of the meta-language, there would be a logically true object-language sentence 'φ' such that K follows from the sentence 'φ is true'. Thus, many logically true sentences would be a posteriori. To prevent this fatal consequence, we propose to alter the invariance criterion: not only the (...) term's extension, but also its semantic clause must satisfy certain invariance conditions. The paper ends with the observation that the new criterion makes explicit the dependency of the classification of terms into logical and non-logical ones at the different levels of the Tarskian hierarchy of languages. (shrink)

In the first section, I consider what several logicians say informally about the notion of logical consequence. There is significant variation among these accounts, they are sometimes poorly explained, and some of them are clearly at odds with the usual technical definition. In the second section, I first argue that a certain kind of informal account—one that includes elements of necessity, generality, and apriority—is approximately correct. Next I refine this account and consider several important questions about it, including the appropriate (...) characterization of necessity, the criterion for selecting logical constants, and the exact role of apriority. I argue, among other things, that there is no need to recognize a special logical sense of necessity and that the selection of terms to serve as logical constants is ultimately a pragmatic matter. In the third section, I consider whether the informal account I have presented and defended is adequately represented by the usual technical definition. I show that it is, and provably so, for certain limited ways of selecting logical constants. In the general case, however, there seems to be no way to be sure that the technical and informal accounts coincide. (shrink)

A theory of true observation is developed as a generalization of the method of inter-observer agreement that scientists use to determine the objectivity and reliability of observations. A true observation is defined as a statement included in a set of statements in which there is statistical dependence and perfect agreement between the statements made by a universe of experimentally independent persons. Meaningfulness--the existence of an objective referent--for each form of statement included in the set is inferred from statistical dependence, correct (...) meaning within the universe of observers from the absence of disagreement. In this theory truth is inferred from a spatio-temporal pattern of statements as behavior rather than from the traditional correspondence between observation and object or logical relationships among statements. (shrink)

This paper offers a response to William’s Hanson’s criticism of Sher’s formal-structural conception of logical consequence and logical constants.

In the first section, I consider what several logicians say informally about the notion of logical consequence. There is significant variation among these accounts, they are sometimes poorly explained, and some of them are clearly at odds with the usual technical definition. In the second section, I first argue that a certain kind of informal account—one that includes elements of necessity, generality, and apriority—is approximately correct. Next I refine this account and consider several important questions about it, including the appropriate (...) characterization of necessity, the criterion for selecting logical constants, and the exact role of apriority. I argue, among other things, that there is no need to recognize a special logical sense of necessity and that the selection of terms to serve as logical constants is ultimately a pragmatic matter. In the third section, I consider whether the informal account I have presented and defended is adequately represented by the usual technical definition. I show that it is, and provably so, for certain limited ways of selecting logical constants. In the general case, however, there seems to be no way to be sure that the technical and informal accounts coincide. (shrink)

NOTE TO THE READER - December, 2021 ●●●●● -/- After a long period of time devoted to research in other areas, the author returned to the subject of this paper in a book-length study, CRITIQUE OF IMPURE REASON: Horizons of Possibility and Meaning. In this book (Chapter 11, “The Metalogic of Meaning”), the position developed in the 1982 paper, "Referential Consistency as a Criterion of Meaning", has been substantively revised and several important corrections made. It is recommended that readers (...) read the revised and corrected version that appears in the book, CRITIQUE OF IMPURE REASON. ●●●●● -/- The book is available in a printed edition, ISBN 978-0-578-88646-6, from online booksellers such as Barnes & Noble, Amazon, and through independent bookstores. The book is also available as a freely downloadable _corrected second edition_ eBook, DOI: 10.5281/zenodo.5458352, through PhilSci, PhilPapers, HAL, and other online archives. ●●●●● -/- In addition to the above-mentioned book, readers may find "A Primer on Bartlett's CRITIQUE OF IMPURE REASON" to be useful as a guide to the nearly 900-page CRITIQUE. The primer is available as a free download through PhilPapers. ●●●●● -/- "Referential Consistency as a Criterion of Meaning" describes a logically compelling criterion of meaning — that is, a necessary condition of meaning, one which is non-arbitrary and compelling. One cannot _not_ accept the proposed criterion without self-referential inconsistency. This “metalogical” variety of self-referential inconsistency is new, opening a third category beyond semantical and pragmatical forms of self-referential inconsistency. ●●●●● -/- It is argued that such a criterion of meaning can serve as an instrument of internal criticism for any theoretical framework that permits reference to a class of objects. The paper combines the concern of the logical empiricists to formulate a rigorous meaning criterion, with the analytical interest in identifying and eliminating self-defeating statements through an analysis of the referential structure of theories. ●●●●● -/- The paper is followed by a list of other publications by the author that further develop and extend the ideas presented here. (shrink)

The book discusses the central notion of logic, the concept of logical consequence, and its model-theoretic definition as truth-preservation in all models. Whether the model-theoretic definition captures the modal and epistemological features of our pre-theoretic notion depends on what models model. The book argues that, given a non-formal understanding of models, the universal quantifier used in the definition of consequence must be restricted: if literally all models had to be considered, no argument would ever be logically valid. A central challenge (...) of the philosophy of logic is therefore to supplement the model-theoretic definition by a criterion for admissible models. The problem of logical constants, so prominent in the current literature on logical consequence, constitutes but a special case of this much more general demarcation problem. The book explores the various dimensions of the problem of admissible interpretations and proposes that the standard views are unjustified or even unjustifiable. As a consequence, it develops a new vision of logic and suggests in particular that our notion of logical consequence is deeply imbued with metaphysics. (shrink)

In a recent discussion article in this journal, Gila Sher responds to some of my criticisms of her work on what she calls the formal-structural account of logical consequence. In the present paper I reply and attempt to advance the discussion in a constructive way. Unfortunately, Sher seems to have not fully understood my 1997. Several of the defenses she mounts in her 2001 are aimed at views I do not hold and did not advance in my 1997. Most prominent (...) among these are her claims that I reject the formal-structural account, because it licenses “unnatural” logical constants, and that I consider the “truth-functional criterion” for connectives “a paradigm of a successful criterion of logicality”. Both of these claims are simply false, as even a moderately careful reading of my 1997 will show. Other charges she makes have some basis in fact but are inaccurate. For example, she says that I claim that FS is “neutral with regard to the apriority of logic,” and that this neutrality “renders it inconsistent”. What I actually say is that Sher’s acceptance of the neutrality in question is “inconsistent with part of the legacy of Tarski, a legacy that she finds very congenial”, not that FS itself is inconsistent. More interestingly, she misunderstands my claim about the apriority of logic, and clarification of this misunderstanding suggests two distinct ways in which logic might be held to be free of empirical influence. It is also noteworthy that Sher’s statements about the apriority of logic constitute both a change in the position she took in her 1991 and, although she seems not to realize it, an admission that she does not take issue with one of my major criticisms. (shrink)

In a recent discussion article in this journal, Gila Sher responds to some of my criticisms of her work on what she calls the formal-structural account of logical consequence. In the present paper I reply and attempt to advance the discussion in a constructive way. Unfortunately, Sher seems to have not fully understood my 1997. Several of the defenses she mounts in her 2001 are aimed at views I do not hold and did not advance in my 1997. Most prominent (...) among these are her claims that I reject the formal-structural account, because it licenses “unnatural” logical constants, and that I consider the “truth-functional criterion” for connectives “a paradigm of a successful criterion of logicality”. Both of these claims are simply false, as even a moderately careful reading of my 1997 will show. Other charges she makes have some basis in fact but are inaccurate. For example, she says that I claim that FS is “neutral with regard to the apriority of logic,” and that this neutrality “renders it inconsistent”. What I actually say is that Sher’s acceptance of the neutrality in question is “inconsistent with part of the legacy of Tarski, a legacy that she finds very congenial”, not that FS itself is inconsistent. More interestingly, she misunderstands my claim about the apriority of logic, and clarification of this misunderstanding suggests two distinct ways in which logic might be held to be free of empirical influence. It is also noteworthy that Sher’s statements about the apriority of logic constitute both a change in the position she took in her 1991 and, although she seems not to realize it, an admission that she does not take issue with one of my major criticisms. (shrink)

De Finetti gave a natural definition of “coherent probability assessment” β:E→[0,1] of a set E={X1,…,Xm} of “events” occurring in an arbitrary set of “possible worlds”. In the particular case of yes–no events, , Kolmogorov axioms can be derived from his criterion. While De Finetti’s approach to probability was logic-free, we construct a theory Θ in infinite-valued Łukasiewicz propositional logic, and show: a possible world of is a valuation satisfying Θ, β is coherent iff it is a convex combination of (...) valuations satisfying Θ, iff β agrees on E with a state of the Lindenbaum MV-algebra of Θ, iff for some Borel probability measure μ on . Thus Łukasiewicz semantics, MV-algebraic states, and Borel probability measures provide a universal representation of coherent assessments of events occurring in any conceivable set of possible worlds. (shrink)

: Any precise version of H-D needs to handle various problems, most notably, the problem of selective confirmation: Precise formulations of H-D should not have the consequence that where S confirms T, for any T', S confirms T&T'. It is the perceived failure of H-D to solve such problems that has lead John Earman to recently conclude that H-D is "very nearly a dead horse". This suggests the following state of play: H-D is an intuitively plausible idea that breaks down (...) in the attempt to give it a precise formulation. Indeed I think that fairly captures the view among specialists in the field of confirmation theory. Here I argue that the truth about H-D is largely the reverse: H-D can be given a precise formulation that avoids the longstanding technical problems, however, it relies on a fundamentally unsound philosophical intuition. The bulk of this paper involves reviewing the problems affecting previous attempts at giving precise formulations of H-D and displaying some recent versions that can handle these problems. It then briefly explains why the basic intuition behind H-D is itself unsound, namely, because H-D involves a tacit assumption of inductive scepticism. Finally, the historical relation between H-D and the positivists' quest for a criterion of empirical significance will be reconsidered with the surprising result that having glossed H-D as fundamentally unsound it is concluded that a sound version of the criterion of empirical significance is now available. The demarcation criterion, the positivists' philosopher's stone that serves to separate claims with empirical significance from claims lacking empirical significance having finally been found, it is argued that we should regard empirical significance as just one among a variety of virtues and not follow the positivists in taking it to be a sin qua non for all meaningful statements. (shrink)