This paper considers a formalisation of classical logic using general introduction rules and general elimination rules. It proposes a definition of ‘maximal formula’, ‘segment’ and ‘maximal segment’ suitable to the system, and gives reduction procedures for them. It is then shown that deductions in the system convert into normal form, i.e. deductions that contain neither maximal formulas nor maximal segments, and that deductions in normal form satisfy the subformula property. Tarski’s Rule is treated as a general introduction rule for implication. (...) The general introduction rule for negation has a similar form. Maximal formulas with implication or negation as main operator require reduction procedures of a more intricate kind not present in normalisation for intuitionist logic. (shrink)

This paper studies a formalisation of intuitionistic logic by Negri and von Plato which has general introduction and elimination rules. The philosophical importance of the system is expounded. Definitions of ‘maximal formula’, ‘segment’ and ‘maximal segment’ suitable to the system are formulated and corresponding reduction procedures for maximal formulas and permutative reduction procedures for maximal segments given. Alternatives to the main method used are also considered. It is shown that deductions in the system convert into normal form and that deductions (...) in normal form have the subformula property. (shrink)

I distinguish two notions of agreement in belief: believing the same content versus having beliefs that necessarily coincide/diverge in normative status. The second notion of agreement,, is clearly significant for the communication of beliefs amongst thinkers. Thus there would seem to be some prima facie advantage to choosing the conception of content operative in in such a way that the normative status of beliefs supervenes on their content, and this seems to be the prevailing assumption of many semanticists. I shall (...) argue that de se beliefs and assertions provide a motivation to depart from this assumption, and so do beliefs and assertions concerning what is epistemically possible. I conclude by offering two models of assertoric communication that are compatible with the abandonment of the assumption, and suggesting schematically that each model applies to different cases. (shrink)

Horizontalism is the thesis that what a speaker asserts in literally and sincerely uttering an indicative sentence is some horizontal proposition of her utterance; diagonalism is the thesis that what a speaker asserts in literally and sincerely uttering an indicative sentence is some diagonal proposition of her utterance. Recent work on assertion has reached no clear consensus favoring either horizontalism or diagonalism. I explore a novel strategy for adjudicating between the two views by considering the advantages and disadvantages which would (...) accrue to a linguistic community as a result of adopting different committal practices—that is, practices of associating utterances with the propositions to which speakers undertake assertoric commitments in uttering them—ultimately concluding that a horizontalist practice has important advantages over its competitors. (shrink)

ABSTRACT. The received picture of linguistic communication understands communication as the transmission of information from speaker's head to hearer's head. This picture is in conflict with the attractive Lewisian view of belief as self-location, which is motivated by de se attitudes – first-personal attitudes about oneself – as well as attitudes about subjective matters such as personal taste. In this paper, I provide a solution to the conflict that reconciles these views. I argue for an account of mental attitudes and (...) communication on which mental content and speech act content is understood as sets of multicentered worlds – roughly, possible worlds ‘centered’ on a sequence of individuals at a time. I develop a Stalnakerian model of communication based on multicentered worlds content, and I provide a suitable semantics for personal pronouns and predicates of personal taste. The resulting picture is one on which the point of conversation is the coordination of individual perspectives. (shrink)

General-elimination harmony articulates Gentzen’s idea that the elimination-rules are justified if they infer from an assertion no more than can already be inferred from the grounds for making it. Dummett described the rules as not only harmonious but stable if the E-rules allow one to infer no more and no less than the I-rules justify. Pfenning and Davies call the rules locally complete if the E-rules are strong enough to allow one to infer the original judgement. A method is given (...) of generating harmonious general-elimination rules from a collection of I-rules. We show that the general-elimination rules satisfy Pfenning and Davies’ test for local completeness, but question whether that is enough to show that they are stable. Alternative conditions for stability are considered, including equivalence between the introduction- and elimination-meanings of a connective, and recovery of the grounds for assertion, finally generalizing the notion of local completeness to capture Dummett’s notion of stability satisfactorily. We show that the general-elimination rules meet the last of these conditions, and so are indeed not only harmonious but also stable. (shrink)

This paper discusses an "expressive constraint" on accounts of thought and language which requires that when a speaker expresses a belief by sincerely uttering a sentence, the utterance and the belief have the same content. It will be argued that this constraint should be viewed as expressing a conceptual connection between thought and language rather than a mere empirical generalization about the two. However, the most obvious accounts of the relation between thought and language compatible with the constraint (giving an (...) independent account of one of either linguistic meaning or thought content and understanding the other in terms of it) both face serious difficulties. Because of this, the following will suggest an alternative picture of the relation between thought and language that remains compatible with the constraint. (shrink)

We present an inferentialist account of the epistemic modal operator might. Our starting point is the bilateralist programme. A bilateralist explains the operator not in terms of the speech act of rejection ; we explain the operator might in terms of weak assertion, a speech act whose existence we argue for on the basis of linguistic evidence. We show that our account of might provides a solution to certain well-known puzzles about the semantics of modal vocabulary whilst retaining classical logic. (...) This demonstrates that an inferentialist approach to meaning can be successfully extended beyond the core logical constants. (shrink)

This paper defends the thesis that counterfactuals are strict conditionals. Its purpose is to show that there is a coherent view according to which counterfactuals are strict conditionals whose antecedent is stated elliptically. Section 1 introduces the view. Section 2 outlines a response to the main argument against the thesis that counterfactuals are strict conditionals. Section 3 compares the view with a proposal due to Aqvist, which may be regarded as its direct predecessor. Sections 4 and 5 explain how the (...) view di ers from the theories of counterfactuals advocated by Stalnaker and Lewis, and from some contextualist strict conditional accounts of counterfactuals that have emerged recently. Finally, section 6 addresses the thorny issue of disjunctive antecedents. (shrink)

This collection maintains a dialogue between the analytic and continental traditions, while aspiring to situate itself beyond the analytic-continental divide. It divides into four parts, Methodologies, Truth and Meaning, Metaphysics and Ontology, and Values, Personhood and Agency, though there is considerable overlap among the categories. History and temporality are recurrent themes, but there is a lot of metaphysics generally, with some philosophy of language, philosophy of social science, ethics, political philosophy and epistemology. Less prominent is a pragmatic, deflationary attitude, and (...) at a number of points I argue for the virtues of such an approach. (shrink)

The interplay of introduction and elimination rules for propositional connectives is often seen as suggesting a distinguished role for intuitionistic logic. We prove three formal results concerning intuitionistic propositional logic that bear on that perspective, and discuss their significance. First, for a range of connectives including both negation and the falsum, there are no classically or intuitionistically correct introduction rules. Second, irrespective of the choice of negation or the falsum as a primitive connective, classical and intuitionistic consequence satisfy exactly the (...) same structural, introduction, and elimination (briefly, elementary) rules. Third, for falsum as primitive only, intuitionistic consequence is the least consequence relation that satisfies all classically correct elementary rules. (shrink)

The central claim is that the semantic knowledge exercised by people when they speak is practical knowledge. The relevant idea of practical knowledge is explicated, applied to the case of speaking, and connected with an idea of agents’ knowledge. Some defence of the claim is provided.

This paper defends the claim that, in order to have a concept of time, subjects must have memories of particular events they once witnessed. Some patients with severe amnesia arguably still have a concept of time. Two possible explanations of their grasp of this concept are discussed. They take as their respective starting points abilities preserved in the patients in question: (1) the ability to retain factual information over time despite being unable to recall the past event or situation that (...) information stems from, and (2) the ability to remember at least some past events or situations themselves (typically because retrograde amnesia is not complete). It is argued that a satisfactory explanation of what it is for subjects to have a concept of time must make reference to their having episodic memories such as those mentioned under (2). It is also shown how the question as to whether subjects have such memories, and thus whether they possess a concept of time, enters into our explanation of their actions. (shrink)

In this paper I propose to inquire into the theory of self-awareness propounded by the two Buddhist epistemologists, Dignaga and Dharmakirti. I first give an outline of the Buddhist notion of consciousness, then deal with the notion of objectual appearance, and finally dwell on the theory itself together with certain arguments in its favor. It is shown that the Buddhists subscribed themselves to the following self-awareness thesis: that our waking consciousness is always pre-reflectively and nonconceptually aware of itself. Adopting an (...) approach of interpretive and comparative analysis, I also clarify significant differences between the theory and the correspondent Cartesian views in order to reveal the theory's contemporary relevancy. (shrink)

Anti-exceptionalism about logic is the Quinean view that logical theories have no special epistemological status, in particular, they are not self-evident or justified a priori. Instead, logical theories are continuous with scientific theories, and knowledge about logic is as hard-earned as knowledge of physics, economics, and chemistry. Once we reject apriorism about logic, however, we need an alternative account of how logical theories are justified and revised. A number of authors have recently argued that logical theories are justified by abductive (...) argument (e.g. Gillian Russell, Graham Priest, Timothy Williamson). This paper explores one crucial question about the abductive strategy: what counts as evidence for a logical theory? I develop three accounts of evidential confirmation that an anti-exceptionalist can accept: (1) intuitions about validity, (2) the Quine-Williamson account, and (3) indispensability arguments. I argue, against the received view, that none of the evidential sources support classical logic. (shrink)

It is common for contemporary ontologists to claim that they are not concerned with what exists simpliciter, but rather with what exists ’fundamentally’, or what ’really’ exists. I argue that positions of this sort cannot satisfy reasonable constraints concerning the acquisition of language. I assess and dismiss possible responses to this complaint before commenting on the prospects for a metaphysics without bespoke existence claims.

To what extent can constructive mathematics based on intuitionistc logic recover the mathematics needed for spacetime physics? Certain aspects of this important question are examined, both technical and philosophical. On the technical side, order, connectivity, and extremization properties of the continuum are reviewed, and attention is called to certain striking results concerning causal structure in General Relativity Theory, in particular the singularity theorems of Hawking and Penrose. As they stand, these results appear to elude constructivization. On the philosophical side, it (...) is argued that any mentalist-based radical constructivism suffers from a kind of neo-Kantian apriorism. It would be at best a lucky accident if objective spacetime structure mirrored mentalist mathematics. the latter would seem implicitly committed to a Leibnizian relationist view of spacetime, but is it doubtful if implementation of such a view would overcome the objection. As a result, an anti-realist view of physics seems forced on the radical constructivist. (shrink)

John McDowell has often emphasized the fact that the use of langauge is a rational enterprise. In this paper, I explore the sense in which this is so, arguing that our use of language depends upon our consciously knowing what our words mean. I call this a 'cognitive conception of semantic competence'. The paper also contains a close analysis of the phenomenon of implicature and some suggestions about how it should and should not be understood.

A reply to two responses to an earlier paper, "A Liar Paradox".

CRS says that the meanings of expressions of a language or other symbol system or the contents of mental states are determined and explained by the way symbols are used in thinking. According to CRS one.

In this paper it is argued that functional role semantics can be saved from criticisms, such as those raised by Putnam and Fodor and Lepore, by indicating which beliefs and inferences are more constitutive in determining mental content. The Scylla is not to use vague expressions; the Charybdis is not to endorse the analytic/synthetic distinction. The core idea is to use reflective equilibrium as a strategy to pinpoint which are the beliefs and the inferences that constitute the content of a (...) mental state. The beliefs and the inferences that are constitutive are those that are in reflective equilibrium in the process of attributing mental states to others. (shrink)

There have been several different and even opposed conceptions of the problem of logical constants, i.e. of the requirements that a good theory of logical constants ought to satisfy. This paper is in the first place a survey of these conceptions and a critique of the theories they have given rise to. A second aim of the paper is to sketch some ideas about what a good theory would look like. A third aim is to draw from these ideas and (...) from the preceding survey the conclusion that most conceptions of the problem of logical constants involve requirements of a philosophically demanding nature which are probably not satisfiable by any minimally adequate theory. (shrink)

The Taming of the True continues the project Neil Tennant began in Anti-realism and Logic of investigating and defending anti-realism. Tennant’s earlier book anticipated a second volume, in which issues related to empirical discourse would be addressed in greater detail. The Taming of the True provides this sequel. It also attempts a ground-clearing project, by addressing challenges to some of the presuppositions and implications of Tennant’s anti-realist position. Finally, it takes an opportunity to revisit some of the issues examined in (...) the earlier book, in light of the evolving debate over realism and anti-realism. (shrink)

This paper argues for the thesis that, roughly put, it is impossible to talk about absolutely everything. To put the thesis more precisely, there is a particular sense in which, as a matter of semantics, quantifiers always range over domains that are in principle extensible, and so cannot count as really being ‘absolutely everything’. The paper presents an argument for this thesis, and considers some important objections to the argument and to the formulation of the thesis. The paper also offers (...) an assessment of just how implausible the thesis really is. It argues that the intuitions against the thesis come down to a few special cases, which can be given special treatment. Finally, the paper considers some metaphysical ideas that might surround the thesis. Particularly, it might be maintained that an important variety of realism is incompatible with the thesis. The paper argues that this is not the case. (shrink)

In Anti-Individualism and Knowledge Jessica Brown criticises views of content that combine Fregean Sense and anti-individualism. Brown assumes that all Fregean theories are motivated by a picture of the rational thinker as someone who will always have transparent access to the simple inferential consequences of his thoughts. This picture, Brown argues, is incompatible with anti-individualism about content. While traditional Fregean theories have indeed had such motivation, Brown’s mistake is in attributing this motivation to the modern Fregean anti-individualist. My goal in (...) this paper is to bring to light a different, and seldom discussed, motivation for Fregean views of content which is immune to Browns objections. (shrink)

Various possibilities, that one is dreaming, that one is being deceived by a deceitful demon, that one is a brain in the vat being stimulated to think one has a body and is in a regular world, have been invoked to show that all one's experience-based beliefs might be false. Descartes in Meditation I advises that in order not to lapse into his careless everyday view of things he, or at least his meditator, should pretend that all his experience-based beliefs, (...) indeed all his …. (shrink)

Fregeans follow Frege in accepting informativeness and substitution failure as reliable criteria for the existence of senses as objects of thought. In this paper I show that if we accept this, we must also accept the existence of an infinite hierarchy of senses as objects of thought. This is a bad result since it turns Fregeanism into a doctrine according to which object-related thoughts either have an infinite number of objects as contents or none at all. This shows, against the (...) Fregean, that senses cannot themselves be constituents of thought. Los fregeanos aceptan, siguiendo a Frege, que los criterios de informatividad y falla de sustitución son guías confiables de la existencia de sentidos como objetos del pensamiento. En este artículo muestro que si aceptamos esta tesis también debemos aceptar la existencia de una jerarquía infinita de sentidos como objetos del pensamiento. Esta es una mala consecuencia pues convierte al fregeanismo en una doctrina según la cual los pensamientos dirigidos a objetos o bien tienen un número infinito de objetos como contenido o ninguno. Esto muestra, contra los fregeanos, que los sentidos no pueden ellos mismos ser objeto del pensamiento. (shrink)

It has been argued in the literature that the deflationists’ thesis about the dispensability of truth as an explanatory notion forces them to adopt a conservative theory of truth. I suggest that the deflationists’ claim that the notion of truth is akin to a logical notion should be taken more seriously. This claim casts some doubts on the adequacy of the conservativity requirement, while it also calls for further investigation to assess its philosophical plausibility.

The paper has two parts: 1. A brief exposition of proof-theoretic semantics, not necessarily in connection to natural language. 2. A review, with a contrastive flavour, of some of the applications of PTS to NL with an indication of advantages of PTS as a theory of meaning for NL.

The paper suggests a revision of the notion of harmony, a major necessary condition in proof-theoretic semantics for a natural-deduction proof-system to qualify as meaning conferring, when moving to a bilateral proof-system. The latter considers both forces of assertion and denial as primitive, and is applied here to positive logics, lacking negation altogether. It is suggested that in addition to the balance between introduction and elimination rules traditionally imposed by harmony, a balance should be imposed also on: negative introduction and (...) elimination rules, and positive and negative introduction rules. The paper suggests a proof-theoretical definition of duality, using which double harmony is defined. The paper proves that in a doubly-harmonious system, the coordination rule, typical to bilateral systems, is admissible. (shrink)

The paper provides a proof-theory for a negative presentation of classical logic based on a single primitive of exclusion, generalizing the known presentation via the binary ‘nand. The completeness is established via deductive equivalence to Gentzens NK/LK systems.

In the proof-theoretic semantics approach to meaning, harmony , requiring a balance between introduction-rules (I-rules) and elimination rules (E-rules) within a meaning conferring natural-deduction proof-system, is a central notion. In this paper, we consider two notions of harmony that were proposed in the literature: 1. GE-harmony , requiring a certain form of the E-rules, given the form of the I-rules. 2. Local intrinsic harmony : imposes the existence of certain transformations of derivations, known as reduction and expansion . We propose (...) a construction of the E-rules (in GE-form) from given I-rules, and prove that the constructed rules satisfy also local intrinsic harmony. The construction is based on a classification of I-rules, and constitute an implementation to Gentzen’s (and Pawitz’) remark, that E-rules can be “read off” I-rules. (shrink)

The combination of quantifiers with a semantics for epistemic operators in a modal framework is one of the major contributions of Hintikka in intensional logic. Hintikka’s starting point is his diagnosis of the failure of existential generalization and the substitution of identicals in terms of referential multiplicity. In this paper, I introduce Hintikka as a free logician. Indeed, Hintikka’s first-order epistemic logic is grounded on a logic free of ontological presuppositions with respect to singular terms. It is also a logic (...) free of presuppositions of uniqueness of reference. After having focused on the use of quantifiers and singular terms in Hintikka’s epistemic logic, I discuss some consequences from a semantico-logical perspective, but also from a philosophical one. By arguing against the so-called contingent a priori truths defended by Kripke, I conclude with a proposal in favour of Hintikka’s non-rigid interpretation of proper names. (shrink)

In "'Yes" and "No'" (2000), Ian Rumfitt proposed bilateralism--a use-based account of the logical words, according to which the sense of a sentence is determined by the conditions under which it is asserted and denied. One of Rumfitt's key claims is that bilateralism can provide a justification of classical logic. This paper raises a techical problem for Rumfitt's proposal, one that seems to undermine the bilateralist programme.

Starting from a proof-theoretic perspective, where meaning is determined by the inference rules governing logical operators, in this paper we primarily aim at developing a proof-theoretic alternative to the model-theoretic meaning-invariant logical pluralism discussed in Beall and Restall. We will also outline how this framework can be easily extended to include a form of meaning-variant logical pluralism. In this respect, the framework developed in this paper—which we label two-level proof-theoretic pluralism—is much broader in scope than the one discussed in Beall (...) and Restall’s book. (shrink)

Social choice and welfare economics are subjects at the frontier of many disciplines. Even if economics played the major role in their development, sociology, psychology and, principally, political science, mathematics and philosophy have been central for the manifold inventiveness of the employed methods and for the diversity of the studied topics. This phenomenon can be compared with game theory, a subject which has, of course, many connections with social choice and welfare. This fact is reflected by the disciplinary origins of (...) the contributors to the subject and, as an anecdote, by the disciplinary origins of the board of editors of this journal. Philosophers are expected to contribute mainly to the study of social justice and related ethical questions. But there is a tradition among logicians for studying voting theory. A famous example is C. L. Dodgson (Lewis Carroll), even though the complete works of Dodgson on voting occupy only a few pages. A major recent example is Michael Dummett. Michael Dummett is famous among social choice theorists for his joint paper with Robin Farquharson published in Econometrica in 1961. Later he wrote two important books on voting (Dummett (1984, 1997); for an overview see Salles (2006)). But it must be outlined that Michael Dummett is also, and above all, one of the greatest contemporary philosophers whose work on the German logician Frege, on intuitionism, realism, anti-realism, justificationism has been central for the development of analytical philosophy in the second part of the last century and in this century (an example is the Symposium in a recent issue of Mind (see Peacocke (2005) and Dummett (2005)). Sir Michael Dummett is Wykeham Professor of Logic emeritus at Oxford University. His interview was conducted at New College, Oxford in September 2004. (shrink)

Je suis trés reconnaissant à Michel Seymour d'avoir soumis mon livre à un examen détaillé, pénétrant, et charitable et d'avoir, par ses objections, mis le doigt sur un certain nombre de présupposés des thèses défendues dans ce livre, qu'il a souvent articulés bien mieux que je n'ai été capable de le faire. Le principal de ces présupposés est mon rejet implicite de la thése quinienne de l'indétermination de la traduction, qui m'engage, selon Seymour, à défendre une conception conservatrice de la (...) logique et à insister sur une détermination de son domaine qui lui paraît injustifiée. Seymour soutient au contraire qu'il faut admettre cette thése, qui «commande une tout autre perspective» que la mienne. Je voudrais à la fois résister à la prémisse et à la conclusion de cette inférence. (shrink)

The main thesis of this paper is that we sometimes are disposed to accept false and even jointly inconsistent claims by virtue of our semantic competence, and that this comes to light in the sorites and liar paradoxes. Among the subsidiary theses are that this is an important source of indeterminacy in truth conditions, that we must revise basic assumptions about semantic competence, and that classical logic and bivalence can be upheld in the face of the sorites paradox.

In this paper I investigate the claim that truth is a relational property. What does this claim really mean? What is its import?—Is it a basic feature of the concept of truth; or a distinctive feature of the correspondence theory of truth; or even both? After introducing some general ideas about truth, I begin by highlighting an ambiguity in current uses of the term ‘relational property’ in the truth debate, and show that we need to distinguish two separate ideas: that (...) truth is a relational property, and that truth is an extrinsic property. I go on to examine what both of these ideas are in more detail, and consider what would need to hold for truth to be in either of these categories. I then discern where all the main competitors in the truth debate stand on these issues. In doing so we learn more about these views and what they entail, and build a general picture of what stances different theories of truth take on whether truth is extrinsic or relational. Moreover, in doing this we will be able to answer one of the questions with which we began: whether truth’s being extrinsic or relational is something that, if accepted, lends support to the correspondence theory of truth. We will see that this is not so, and discern some interesting variations between various theories of truth on the issues of whether truth is extrinsic or relational. Following this we will be in a better position to judge whether the notions of extrinsicality or relationality are basic features of the concept of truth. In the final part of the paper I argue that, even if we are not in a position to conclude that they are basic features, they are features that any prospective theory of truth needs to take seriously. (shrink)

This paper identifies the difficulties in confronting novel history from both a rigorous scientific and artistic literary perspectives and suggests a practical reconciliation—in the form of a discussion and metaphorical opening space—between the two apparent poles of historical understanding and their accompanying genres, types, and tropes.

Our utterances are typically if not always "situated," in the sense that they are true or false relative to unarticulated parameters of the extra-linguistic context. The problem is to explain how these parameters are determined, given that nothing in the uttered sentences indicates them. It is tempting to claim that they must be determined at the level of thought or intention. However, as many philosophers have observed, thoughts themselves are no less situated than utterances. Unarticulated parameters need not be mentally (...) represented. In this paper, I try to make precise the notion of representation at stake here. In one sense of 'representation', something is represented if it is inferentially relevant. In another, less demanding sense, something is represented if it is relevant to the construction of a context-sensitive, ad hoc concept. Ad hoc concepts act as "proxies" for cognitively more demanding representations. They "imitate" the latter's epistemic and pragmatic roles while being inferentially less sophisticated. Thus, there are two senses in which a thought can be said to be situated: (1) its truth-value is relative to a non-represented contextual parameter, (2) its truth-value is not itself relative, but it involves a context-sensitive, ad hoc concept. (shrink)

What accounts for how we know that certain rules of reasoning, such as reasoning by Modus Ponens, are valid? If our knowledge of validity must be based on some reasoning, then we seem to be committed to the legitimacy of rule-circular arguments for validity. This paper raises a new difficulty for the rule-circular account of our knowledge of validity. The source of the problem is that, contrary to traditional wisdom, a universal generalization cannot be inferred just on the basis of (...) reasoning about an arbitrary object. I argue in favor of a more sophisticated constraint on reasoning by universal generalization, one which undermines a rule-circular account of our knowledge of validity. (shrink)

Intra-theoretical logical pluralism is a form of meaning-invariant pluralism about logic, articulated recently by Hjortland :355–373, 2013). This version of pluralism relies on it being possible to define several distinct notions of provability relative to the same logical calculus. The present paper picks up and explores this theme: How can a single logical calculus express several different consequence relations? The main hypothesis articulated here is that the divide between the internal and external consequence relations in Gentzen systems generates a form (...) of intra-theoretical logical pluralism. (shrink)

A logical constant is weakly disharmonious if its elimination rules are weaker than its introduction rules. Substructural weak disharmony is the weak disharmony generated by structural restrictions on the eliminations. I argue that substructural weak disharmony is not a defect of the constants which exhibit it. To the extent that it is problematic, it calls into question the structural properties of the derivability relation. This prompts us to rethink the issue of controlling the structural properties of a logic by means (...) of harmony. I argue that such a control is possible and desirable. Moreover, it is best achieved by global tests of harmony. (shrink)

Proof-theoretic semantics is an alternative to model-theoretic semantics. It aims at explaining the meaning of the logical constants in terms of the inference rules that govern their behaviour in proofs. We argue that this must be construed as the task of explaining these meanings relative to a logic, i.e., to a consequence relation. Alas, there is no agreed set of properties that a relation must have in order to qualify as a consequence relation. Moreover, the association of a consequence relation (...) to a logical calculus is not as straightforward as it may seem. We show that these facts are problematic for the proof-theoretic project but the problems can be solved. Our thesis is that the consequence relation relevant for proof-theoretic semantics is the one given by the sequent-to-sequent derivability relation in Gentzen systems. (shrink)

In the recent literature on proof-theoretic semantics, there is mention of a generality condition on defining rules. According to this condition, the schematic formulation of the defining rules must be maximally general, in the sense that no restrictions should be placed on the contexts of these rules. In particular, context variables must always be present in the schematic rules and they should range over arbitrary collections of formulae. I argue against imposing such a condition, by showing that it has undesirable (...) results and that it is ill-supported by the arguments brought in its favour. (shrink)