This volume contains articles covering a broad spectrum of proof theory, with an emphasis on its mathematical aspects. The articles should not only be interesting to specialists of proof theory, but should also be accessible to a diverse audience, including logicians, mathematicians, computer scientists and philosophers. Many of the central topics of proof theory have been included in a self-contained expository of articles, covered in great detail and depth. The chapters are arranged so that the two introductory (...) articles come first; these are then followed by articles from core classical areas of proof theory; the handbook concludes with articles that deal with topics closely related to computer science. (shrink)

Neil Tennant presents an original logical system with unusual philosophical, proof-theoretic, metalogical, computational, and revision-theoretic virtues. Core Logic is the first system that ensures both relevance and adequacy for the formalization of all mathematical and scientific reasoning.

Responsible Research and Innovation (RRI) is described as a new way of doing science that brings science closer to society. Based on a qualitatively oriented case study, this article supports previous research indicating that researchers face a variety of ethical problems and dilemmas when implementing RRI for the first time. These include difficulties with anticipating and controlling future impacts, an asymmetry of power between project partners and an elusive understanding of the RRI concept. The researchers’ challenges were rooted in conventional (...) research ethics and could be boiled down to one core dilemma: If RRI had been applied from the very beginning of the project period, the chance of realising proof of concept within the scheduled time may decrease. The researchers’ solution to this dilemma was to prioritize proof of concept and postpone RRI activities to later stages of the project. If RRI is expected to live up to its ambition of representing a new way of doing science, more effort is needed at the political level to facilitate change. (shrink)

Neil Tennant’s core logic is a type of bilateralist natural deduction system based on proofs and refutations. We present a proof system for propositional core logic, explain its connections to bilateralism, and explore the possibility of using it as a type theory, in the same kind of way intuitionistic logic is often used as a type theory. Our proof system is not Tennant’s own, but it is very closely related, and determines the same consequence relation. The (...) difference, however, matters for our purposes, and we discuss this. We then turn to the question of strong normalization, showing that although Tennant’s proof system for core logic is not strongly normalizing, our modified system is. (shrink)

Propositional logic -- Predicate logic -- Proof strategies and diagrams -- Mathematical induction -- Set theory -- Functions -- Relations -- Core concepts in abstract algebra -- Core concepts in real analysis.

In the first chapter, we discuss Dummett’s idea that the notion of truth arises from the one of the correctness of an assertion. We argue that, in a first-order language, the need of defining truth in terms of the notion of satisfaction, which is yielded by the presence of quantifiers, is structurally analogous to the need of a notion of truth as distinct from the one of correctness of an assertion. In the light of the analogy between predicates in Frege (...) and open formulas in Tarksi, we concentrate on the semantic status of predicates. We register a dual attitude of Dummett towards Frege’s ascription of reference to predicates. On the one it is needed to endow quantifiers with their appropriate meaning. On the other hand, the introduction of concepts, as semantic correlate of predicates, smuggles a realist flavor in the overall semantic picture. In concluding the excursus (and with it the chapter), we stress Dummett’s will of developing a semantic picture free from this realist trait. In the second chapter, we present the idea of a proof-theoretic semantics. As for Frege true sentences denotes the truth-value True, so here closed' (i.e. categorical) valid argumentations denotes proofs. If a language contains implication-like operators, in order to characterize the condition of validity of a closed argumentation one has to introduce a notion of validity applying to ‘open’ (i.e. hypothetical) argumentations. We argue that this problem is analogous to the one posed by quantifiers in Frege-Tarksi’s style semantics. That is, implication forces one to introduce notion of validity for argumentations, which is more substantial than the correctness of the assertion of their conclusions. As we saw, the corresponding claim in the truth-based approach—that quantifiers require one to introduce a notion of truth, which is more substantial than the one of an assertion being correct—was the source of realism. Hence, Dummett proposes to reduce the semantic contribution of open argumentations to the one of their ‘closed instances’. In the truth-based perspective, this would correspond to the denial of the need of introducing concepts as the semantic correlates of predicates. We argue that Dummett’s fear, that an irreducible notion of function (represented by the need of ascribing validity to open argumentations) would lead to realism, turns out to be ill-founded. In the third chapter, we discuss the role played by the notion of truth in the anti-realist account. The notion of truth is what the anti-realist needs to cope with the so-called paradox of deduction. The analysis of the paradox yields to distinguishing between the truth of a sentence and the truth of a sentence being recognized. In terms of these conceptual couple, we reconsider the relationship between truth and assertion in an anti-realist perspective. Grounds are provided for a thesis (which was already advanced in chapter two), according to which the notion of the assertion of a sentence being correct is primarily connected only with the canonical means of establishing a sentence. The possibility of establishing a sentence by indirect means is conceptually dependent on the practice of establishing logical relationship of dependence among sentences. That is, the notion of a closed valid non-canonical argumentation is of any theoretical relevance only in presence of a notion of validity applying to open argumentations. In the fourth chapter, we discuss the possibility of characterizing in the proof-theoretic-semantics a notion of refutation. We develop an original characterization of refutations starting from an informal inductive specification of the condition of refutations of logically complex sentences. A sub-structural logic, called dual-intuitionistic logic, stands to this notion in the same relationship in which intuitionistic logic stands to the notion of proof so far consdered. All notions developed in chapter 2 have their corresponding (dual) ones in the framework developed. In particular, the distinctions canonical/non-canonical and closed/open argumentations. In the refutation based perspective, elimination rules have priority over introductions and the (only) assumption over the (many) conclusions. In the conclusions, we indicate the ingredients that an anti-realist approach to meaning should incorporate, in order to avoid the difficulties we registered. The core of an alternative view is a different conception of the relationship between categorical and hypothetical notions, in which the validity of open argumentations is not reduced to that of their instances, but rather it is directly defined. As a limit case, one would get a notion of validity applying to closed argumentations. (shrink)

In Prior Analytics 1.15 Aristotle undertakes to establish certain modal syllogisms of the form XQM. Although these syllogisms are central to his modal system, the proofs he offers for them are problematic. The precise structure of these proofs is disputed, and it is often thought that they are invalid. We propose an interpretation which resolves the main difficulties with them: the proofs are valid given a small number of intrinsically plausible assumptions, although they are in tension with some claims found (...) elsewhere in Aristotle’s modal syllogistic. The proofs make use of a rule of propositional modal logic which we call the possibility rule. We investigate how this rule interacts and coheres with the core elements of the modal syllogistic. (shrink)

In lieu of an abstract, here is a brief excerpt of the content:Proof and Persuasion in Black Athena:: The Case of K. O. MüllerJosine H. BlokNon tali auxilio.Virgil, Aeneid II, 521When in 1824 the German classical scholar Karl Otfried Müller (1797–1840) set down to write a review of Champollion’s first Letter to M. Dacier (1822), he was profoundly interested. 1 For several years he had been working on Egypt, and as he told his parents in 1820, “I have come (...) to love Egyptian antiquity so much, that, if I were not constricted by the schedule of my classes, I would have set myself to the decipherment of the hieroglyphs, which I would not deem impossible by the clues I have found.” 2 During the same years (1820–25) that he wrote his early books on ancient Greece, he [End Page 705] reviewed sixteen studies on Egypt alone. 3 In his review of the Letter, then, he wanted to draw “the attention of [the] readers to this, certainly not unfounded, discovery,” 4 though he feared the author was inclined to jump to conclusions. But in August 1824 he reviewed Champollion’s more complete publication of his findings of the same year and, recalling his previous anxiety, commented:Now, however, the reading of the present work has totally convinced me, that the usage of hieroglyphs to indicate sounds is as ancient as this writing system itself. [... This discovery should also mean that...] the history of Egyptian religion and state will be reconstructed and expanded. 5From that moment he sided unequivocally with Champollion, politely but clearly reminding German colleagues who still stumbled on with decipherments of their own, that this would not do. 6With these facts in mind, Martin Bernal’s rendering in his Black Athena, volume I, is bound to surprise: “[U]nlike Humboldt, Niebuhr and Bunsen [Müller] disregarded the sensational scholarly developments between 1815 and 1830. There is no indication that he paid any attention to Champollion’s decipherment” (316). The contradiction between Bernal’s statements and the sources on Müller’s life and work turns out not to be an incidental error but part of a larger pattern. To understand this pattern and its objectives, let me first summarize Bernal’s argument and my own.In his challenging book Bernal argues that the ancient Greek world was founded on the colonization of Greece by Phoenicians and Egyptians in the second millennium bc. 7 The material which is to prove his thesis is offered in volume II, though volume I includes a summary. In this first volume Bernal observes that from late antiquity until the eighteenth century, awareness of the Afroasiatic roots of ancient civilization had been retained as the heritage of ancient Greece itself. Hence Bernal labels this perception underlying Western classical scholarship of the early modern period the “Ancient Model.” By or soon after the 1820s, however, it was replaced by the “Aryan Model,” which took Greek civilization to be partly autochthonous and partly [End Page 706] shaped by invasions coming from the North. To reveal that the fall of the Ancient Model was not the result of internal developments in classical scholarship but of externalist influences, notably the belief in progress, the defense of Christianity, Romanticism, and most importantly racism, is the core theme of volume I. Bernal sustains his argument by contending that historical source criticism was not really or entirely an internal development but created to serve the external ends, and by presenting Müller as the embodiment of Romanticist racism, who was responsible for overthrowing the Ancient Model and inaugurating its Aryan successor. Hence, by thus designating Müller as the axis around which the overall turn of classical scholarship revolved, he wants to prove that the fall of the Ancient Model was unjustified in terms of scholarship but only occurred due to dishonorable ideologies.Through a limited number of representative issues I want to argue that Bernal’s rendering of Müller and the context of his work is untenable in the light of the source material and that Bernal’s explanation of the fall of the Ancient Model is untenable as well. My aim is not just to clear Müller’s name... (shrink)

This fundamental and straightforward text addresses a weakness observed among present-day students, namely a lack of familiarity with formal proof. Beginning with the idea of mathematical proof and the need for it, associated technical and logical skills are developed with care and then brought to bear on the core material of analysis in such a lucid presentation that the development reads naturally and in a straightforward progression. Retaining the core text, the second edition has additional worked (...) examples which users have indicated a need for, in addition to more emphasis on how analysis can be used to tell the accuracy of the approximations to the quantities of interest which arise in analytical limits. (shrink)

Validity, the central concept of the so-called ‘proof-theoretic semantics’ is described as correctly applying to the arguments that denote proofs. In terms of validity, I propose an anti-realist characterization of the notions of truth and correct assertion, at the core of which is the idea that valid arguments may fail to be recognized as such. The proposed account is compared with Dummett’s and Prawitz’s views on the matter.

The core idea of the ontological proof is to show that the concept of existence is somehow contained in the concept of God, and that therefore God’s existence can be logically derived—without any further assumptions about the external world—from the very idea, or definition, of God. Now, G.W. Leibniz has argued repeatedly that the traditional versions of the ontological proof are not fully conclusive, because they rest on the tacit assumption that the concept of God is possible, (...) i.e. free from contradiction. A complete proof will rather have to consist of two parts. First, a proof of premiseGod is possible. Second, a demonstration of the “remarkable proposition”If God is possible, then God exists. The present contribution investigates an interesting paper in which Leibniz tries to prove proposition. It will be argued that the underlying idea of God as a necessary being has to be interpreted with the help of a distinguished predicate letter ‘E’ as follows:\\). Proposition which Leibniz considered as “the best fruit of the entire logic” can then be formalized as follows:\) \rightarrow \, E)\). At first sight, Leibniz’s proof appears to be formally correct; but a closer examination reveals an ambiguity in his use of the modal notions. According to, the possibility of the necessary being has to be understood in the sense of something which possibly exists. However, in other places of his proof, Leibniz interprets the assumption that the necessary being is impossible in the diverging sense of something which involves a contradiction. Furthermore, Leibniz believes that an »impossible thing«, y, is such that contradictory propositions like \\) and \\) might both be true of y. It will be argued that the latter assumption is incompatible with Leibniz’s general views about logic and that the crucial proof is better reinterpreted as dealing with the necessity, possibility, and impossibility of concepts rather than of objects. In this case, the counterpart of turns out to be a theorem of Leibniz’s second order logic of concepts; but in order to obtain a full demonstration of the existence of God, the counterpart of, i.e. the self-consistency of the concept of a necessary being, remains to be proven. (shrink)

The core language can be extended by defining additional logical constants. E.g., we can add ‘→’ (implication), ‘∨’ (disjunction), and ‘∀x’ (universal quantifiers). The choice of logical primitives is not as optional in DPL as it is in standard predicate logic.

The motivation for Core Logic is explained. Its system of proof is set out. It is then shown that, although the system has no Cut rule, its relation of deducibility obeys Cut with epistemic gain.

Scholars who consider that the Transcendental Analytic contains the core of what Kant calls ‘transcendental idealism’ are mistaken. Indeed, Kant’s transcendental idealism of space, time and spatiotemporal objects is sufficiently proved in the Transcendental Aesthetic and does not depend on complementary claims made later on in the Critique. This does not mean, however, that we are allowed to subscribe to the so-called separability-thesis, which states that we can endorse Kant's views in the Transcendental Logic without endorsing the results of (...) the expositions and arguments laid out in the Aesthetic. Nor does it mean that the Aesthetic contains the only proof for transcendental idealism. Indeed, as Kant himself explicitly recognizes, the antinomies provide the premise for an indirect or mediate proof of his position with respect to the nature of space and time. First, I analyze Kant’s argument for the claim that the production of transcendental illusion is inherent to the function of human reasoning, and therefore inevitable. I then follow the presuppositions and the argumentation of the mediate proof of transcendental idealism and argue that it has a more general validity than could be assumed on the basis of Kant’s text, because it is in its essence independent from the particular determinations of the cosmological idea in the form of the four antinomies. Indeed, as I argue, the nature of reason itself and the content of the general cosmological idea suffice as elements for a mediate proof. Thus, I claim that transcendental idealism can be mediately established on the basis of the general antinomical relation between transcendental realism and material idealism, without any requirement to refer to the particular realisations of this antagonism as they are presented in the four antinomies. If the argument is correct, it shows that the mediate proof of transcendental idealism does not depend on a sympathetic account of the antinomies and is not automatically invalidated if the proofs of thesis and antithesis are considered unconvincing. (shrink)

I use the Corcoran–Smiley interpretation of Aristotle's syllogistic as my starting point for an examination of the syllogistic from the vantage point of modern proof theory. I aim to show that fresh logical insights are afforded by a proof-theoretically more systematic account of all four figures. First I regiment the syllogisms in the Gentzen–Prawitz system of natural deduction, using the universal and existential quantifiers of standard first-order logic, and the usual formalizations of Aristotle's sentence-forms. I explain how the (...) syllogistic is a fragment of my system of Core Logic. Then I introduce my main innovation: the use of binary quantifiers, governed by introduction and elimination rules. The syllogisms in all four figures are re-proved in the binary system, and are thereby revealed as all on a par with each other. I conclude with some comments and results about grammatical generativity, ecthesis, perfect validity, skeletal validity and Aristotle's chain principle. (shrink)

Berkeley in his Introduction to the Principles of Human knowledge uses geometrical examples to illustrate a way of generating “universal ideas,” which allegedly account for the existence of general terms. In doing proofs we might, for example, selectively attend to the triangular shape of a diagram. Presumably what we prove using just that property applies to all triangles.I contend, rather, that given Berkeley’s view of extension, no Euclidean triangles exist to attend to. Rather proof, as Berkeley would normally assume, (...) requires idealizing diagrams; treating them as if they obeyed Euclidean constraints. This convention solves the problem of representative generalization. View HTML Send article to KindleTo send this article to your Kindle, first ensure [email protected] is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about sending to your Kindle. Find out more about sending to your Kindle. Note you can select to send to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply. Find out more about the Kindle Personal Document Service.Berkeley and Proof in GeometryVolume 51, Issue 3RICHARD J. BROOK DOI: https://doi.org/10.1017/S0012217312000686Your Kindle email address Please provide your Kindle [email protected]@kindle.com Available formats PDF Please select a format to send. By using this service, you agree that you will only keep articles for personal use, and will not openly distribute them via Dropbox, Google Drive or other file sharing services. Please confirm that you accept the terms of use. Cancel Send ×Send article to Dropbox To send this article to your Dropbox account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about sending content to Dropbox. Berkeley and Proof in GeometryVolume 51, Issue 3RICHARD J. BROOK DOI: https://doi.org/10.1017/S0012217312000686Available formats PDF Please select a format to send. By using this service, you agree that you will only keep articles for personal use, and will not openly distribute them via Dropbox, Google Drive or other file sharing services. Please confirm that you accept the terms of use. Cancel Send ×Send article to Google Drive To send this article to your Google Drive account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about sending content to Google Drive. Berkeley and Proof in GeometryVolume 51, Issue 3RICHARD J. BROOK DOI: https://doi.org/10.1017/S0012217312000686Available formats PDF Please select a format to send. By using this service, you agree that you will only keep articles for personal use, and will not openly distribute them via Dropbox, Google Drive or other file sharing services. Please confirm that you accept the terms of use. Cancel Send ×Export citation Request permission. (shrink)

This volume is dedicated to Prof. Dag Prawitz and his outstanding contributions to philosophical and mathematical logic. Prawitz's eminent contributions to structural proof theory, or general proof theory, as he calls it, and inference-based meaning theories have been extremely influential in the development of modern proof theory and anti-realistic semantics. In particular, Prawitz is the main author on natural deduction in addition to Gerhard Gentzen, who defined natural deduction in his PhD thesis published in 1934. The book (...) opens with an introductory paper that surveys Prawitz's numerous contributions to proof theory and proof-theoretic semantics and puts his work into a somewhat broader perspective, both historically and systematically. Chapters include either in-depth studies of certain aspects of Dag Prawitz's work or address open research problems that are concerned with core issues in structural proof theory and range from philosophical essays to papers of a mathematical nature. Investigations into the necessity of thought and the theory of grounds and computational justifications as well as an examination of Prawitz's conception of the validity of inferences in the light of three “dogmas of proof-theoretic semantics” are included. More formal papers deal with the constructive behaviour of fragments of classical logic and fragments of the modal logic S4 among other topics. In addition, there are chapters about inversion principles, normalization of p roofs, and the notion of proof-theoretic harmony and other areas of a more mathematical persuasion. Dag Prawitz also writes a chapter in which he explains his current views on the epistemic dimension of proofs and addresses the question why some inferences succeed in conferring evidence on their conclusions when applied to premises for which one already possesses evidence. (shrink)

Bilateral proof systems, which provide rules for both affirming and denying sentences, have been prominent in the development of proof-theoretic semantics for classical logic in recent years. However, such systems provide a substantial amount of freedom in the formulation of the rules, and, as a result, a number of different sets of rules have been put forward as definitive of the meanings of the classical connectives. In this paper, I argue that a single general schema for bilateral (...) class='Hi'>proof rules has a reasonable claim to inferentially articulating the core meaning of all of the classical connectives. I propose this schema in the context of a bilateral sequent calculus in which each connective is given exactly two rules: a rule for affirmation and a rule for denial. Positive and negative rules for all of the classical connectives are given by a single rule schema, harmony between these positive and negative rules is established at the schematic level by a pair of elimination theorems, and the truth-conditions for all of the classical connectives are read off at once from the schema itself. (shrink)

Is it possible to characterize the notion of proof in terms of acts, without focusing on a specific domain of application and a specific linguistic formalization of it? This is the question that this paper addresses through a comparative analysis between two logicians who reflected on this issue: Kurt Gödel and Jean-Yves Girard. A comparative analysis of their respective theoretical frames, their respective results, the similarities and the differences between their methodological assumptions is proposed. More specifically, the aim of (...) the paper is to compare Gödel’s notion of absolute proof and Girard’s notion of Ludic from their common core: a conception of proof in terms of acts. (shrink)

This volume is dedicated to Prof. Dag Prawitz and his outstanding contributions to philosophical and mathematical logic. Prawitz's eminent contributions to structural proof theory, or general proof theory, as he calls it, and inference-based meaning theories have been extremely influential in the development of modern proof theory and anti-realistic semantics. In particular, Prawitz is the main author on natural deduction in addition to Gerhard Gentzen, who defined natural deduction in his PhD thesis published in 1934. The book (...) opens with an introductory paper that surveys Prawitz's numerous contributions to proof theory and proof-theoretic semantics and puts his work into a somewhat broader perspective, both historically and systematically. Chapters include either in-depth studies of certain aspects of Dag Prawitz's work or address open research problems that are concerned with core issues in structural proof theory and range from philosophical essays to papers of a mathematical nature. Investigations into the necessity of thought and the theory of grounds and computational justifications as well as an examination of Prawitz's conception of the validity of inferences in the light of three “dogmas of proof-theoretic semantics” are included. More formal papers deal with the constructive behaviour of fragments of classical logic and fragments of the modal logic S4 among other topics. In addition, there are chapters about inversion principles, normalization of proofs, and the notion of proof-theoretic harmony and other areas of a more mathematical persuasion. Dag Prawitz also writes a chapter in which he explains his current views on the epistemic dimension of proofs and addresses the question why some inferences succeed in conferring evidence on their conclusions when applied to premises for which one already possesses evidence. (shrink)

Does syllogistic logic have the resources to capture mathematical proof? This volume provides the first unified account of the history of attempts to answer this question, the reasoning behind the different positions taken, and their far-reaching implications. Aristotle had claimed that scientific knowledge, which includes mathematics, is provided by syllogisms of a special sort: 'scientific' ('demonstrative') syllogisms. In ancient Greece and in the Middle Ages, the claim that Euclid's theorems could be recast syllogistically was accepted without further scrutiny. Nevertheless, (...) as early as Galen, the importance of relational reasoning for mathematics had already been recognized. Further critical voices emerged in the Renaissance and the question of whether mathematical proofs could be recast syllogistically attracted more sustained attention over the following three centuries. Supported by more detailed analyses of Euclidean theorems, this led to attempts to extend logical theory to include relational reasoning, and to arguments purporting to reduce relational reasoning to a syllogistic form. Philosophical proposals to the effect that mathematical reasoning is heterogenous with respect to logical proofs were famously defended by Kant, and the implications of the debate about the adequacy of syllogistic logic for mathematics are at the very core of Kant's account of synthetic a priori judgments. While it is now widely accepted that syllogistic logic is not sufficient to account for the logic of mathematical proof, the history and the analysis of this debate, running from Aristotle to de Morgan and beyond, is a fascinating and crucial insight into the relationship between philosophy and mathematics. (shrink)

There is a familiar derivation of G¨ odel’s Theorem from the proof by diagonalization of the unsolvability of the Halting Problem. That proof, though, still involves a kind of self-referential trick, as we in effect construct a sentence that says ‘the algorithm searching for a proof of me doesn’t halt’. It is worth showing, then, that some core results in the theory of partial recursive functions directly entail G¨ odel’s First Incompleteness Theorem without any further self-referential (...) trick. (shrink)

In practice, mathematical proofs are most often the result of careful planning by the agents who produced them. As a consequence, each mathematical proof inherits a plan in virtue of the way it is produced, a plan which underlies its “architecture” or “unity”. This paper provides an account of plans and planning in the context of mathematical proofs. The approach adopted here consists in looking for these notions not in mathematical proofs themselves, but in the agents who produced them. (...) The starting point is to recognize that to each mathematical proof corresponds a proof activity which consists of a sequence of deductive inferences—i.e., a sequence of epistemic actions—and that any written mathematical proof is only a report of its corresponding proof activity. The main idea to be developed is that the plan of a mathematical proof is to be conceived and analyzed as the plan of the agent(s) who carried out the corresponding proof activity. The core of the paper is thus devoted to the development of an account of plans and planning in the context of proof activities. The account is based on the theory of planning agency developed by Michael Bratman in the philosophy of action. It is fleshed out by providing an analysis of the notions of intention—the elementary components of plans—and practical reasoning—the process by which plans are constructed—in the context of proof activities. These two notions are then used to offer a precise characterization of the desired notion of plan for proof activities. A fruitful connection can then be established between the resulting framework and the recent theme of modularity in mathematics introduced by Jeremy Avigad. This connection is exploited to yield the concept of modular presentations of mathematical proofs which has direct implications for how to write and present mathematical proofs so as to deliver various epistemic benefits. The account is finally compared to the technique of proof planning developed by Alan Bundy and colleagues in the field of automated theorem proving. The paper concludes with some remarks on how the framework can be used to provide an analysis of understanding and explanation in the context of mathematical proofs. (shrink)

Ralph Johnson argues that mathematical proofs lack a dialectical tier, and thereby do not qualify as arguments. This paper argues that, despite this disavowal, Johnson’s account provides a compelling model of mathematical proof. The illative core of mathematical arguments is held to strict standards of rigour. However, compliance with these standards is itself a matter of argument, and susceptible to challenge. Hence much actual mathematical practice takes place in the dialectical tier.

This open access book investigates the role played by identity of proofs in proof-theoretic semantics. It develops a conception of proof-theoretic semantics as primarily concerned with the relationship between proofs (understood as abstract entities) and derivations (the linguistic representations of proofs). It demonstrates that identity of proof is a key both to clarify some —still not wholly understood— notions at the core of proof-theoretic semantics, such as harmony; and to broaden the range of the phenomena (...) which can be analyzed using the tools of this semantic paradigm, so as to include for instance paradoxes. The volume covers topics such as the philosophical significance of different criteria of identity of proofs, and adequacy conditions for an intensional account of the notion of harmony. The author also examines the Prawitz-Tennant analysis of paradoxes by investigating on the one hand the prospects of turning it into a theory of meaning for paradoxical languages, and on the other hand two distinct kinds of phenomena, first observed by Crabbe and Ekman, showing that the Tennant-Prawitz criterion for paradoxicality overgenerates. This volume is of interest to scholars in formal and philosophical logic. (shrink)

Esta reflexão pretende mostrar o discurso racional cartesiano na segunda prova da existência de Deus. Para tanto, Descartes se depara com uma pergunta central: qual a causa da existência da res cogitans que é finita e possui a ideia de infinito? A resposta é encontrada na desproporcionalidade ontológica entre o finito e o infinito. Essa desproporcionalidade é elucidada mediante dois conceitos: o princípio de causalidade que determina que a causa deve ser igual ou superior a coisa causada e o princípio (...) de criação contínua em que a causa que criou o ser não é menor do que aquela que o conserva em sua existência. As objeções destacadas no texto contra os argumentos cartesianos foram escolhas deliberadas que servem para elucidar a importância da racionalidade como fundamento para a prova da existência de Deus. A relação entre o entendimento e a liberdade, apresentada no texto sucintamente, justifica a impossibilidade da res cogitans ser causa de si mesma. Palavras-chave: Infinito; finito; causalidade; criação contínuaThis essay aims to show the rational Cartesian discourse on the second proof of God’s existence. In order to do so, Descartes faces a core question: which is the cause for the existence of the res cogitans that is finite in front of the idea of the infinite? The answer is found in the ontological disproportionality between the finite and the infinite. This disproportionality is elucidated through a couple crucial concepts: the principle of causality, which determines that the cause must be equal or superior to the caused thing and the principle of continuous creation, in which the cause that created the being is not inferior than the one that preserves its existence. The objections highlighted in the text against the Cartesian arguments were deliberated choices, to elucidate the relevance of rationality as the foundation for the proof of God’s existence. The relation between the understanding and the liberty, showed on the text even if succinctly, justifies the impossibility of the res cogitans to be the cause of itself. Key words: Infinite; finite; causality; creation continuous. (shrink)

The evolution of the understanding of evidence-based proof and decision processes in the law, especially criminal law, and standards of proof in this area, has a long-standing and controversial history. Competing accounts cause the legal scholarship to engage in critical and thoughtful exchanges. Some of the divergent views reflect different methodological perspectives similarly recognized in other fields, such as applied psychology and economy, and the broader interdisciplinary research fields of judgment and decision-making, system analysis and decision science. One (...) such methodological perspective asserts that accounts of juridical proof should provide a description and explanation of how the legal system actually works as a whole. Other—more mathematical and analytical accounts—concentrate on how, ideally, legal decision-making under uncertainty ought to be made in order be considered sensible. This paper focuses on the relative plausibility account advocated by Professors Allen and Pardo as an example of the former perspective. Its logical structure and argumentative implications are analysed using elements of decision theory, which is the prime representative of the latter, more mathematical approach to legal proof. Using formal diagrammatic schemes to depict the structural relationships between the core elements of the two accounts, it is demonstrated in what sense they can be considered logically related and congruent. The demonstration shows that the principal disagreements among the proponents of the two examined theories derive from differences in the criteria used to judge the adequacy of competing accounts of legal decision-making, and the level of formalization of the bases of decisions in each candidate account. This structural analysis supports the view that adherence to one or the other of the examined perspectives does not imply a contradiction, but reflects the coverage of different aspects of the same overall decision architecture. Using decision-theoretic notions, our analyses also provide a way to explain RP decisions through an explicit criterion, thus providing a reply to the recurrent critique that RP theory lacks specific means to justify its decisional framework. (shrink)

This article is a methodological discussion of formal approaches to the question of identity of proofs from a philosophical standpoint. First, an introduction to the question of identity of proofs itself is given, followed by a brief reconstruction of the so-called normalisation thesis, proposed by Dag Prawitz in 1971, in which some of its core mathematical and conceptual traits are presented. After that, a comparison between the normalisation thesis and the more well-known Church-Turing thesis on computability is carried out (...) in three main parts: the first dedicated to highlighting some of the analogies between them; the second, their most remarkable differences; and the third, to the possible relations of dependence between the two. Based on these considerations, some concluding remarks concerning the potential of the normalisation thesis and similar approaches to the question of identity of proofs are made in the last section. (shrink)

We explore the consequences, for logical system-building, of taking seriously the aim of having irredundant rules of inference, and a preference for proofs of stronger results over proofs of weaker ones. This leads one to reconsider the structural rules of REFLEXIVITY, THINNING, and CUT. REFLEXIVITY survives in the minimally necessary form $\varphi:\varphi$. Proofs have to get started. CUT is subject to a CUT-elimination theorem, to the effect that one can always make do without applications of CUT. So CUT is redundant, (...) and should not be a rule of the system. CUT-elimination, however, in the context of the usual forms of logical rules, requires the presence, in the system, of THINNING. But THINNING, it turns out, is not really necessary. Provided only that one liberalizes the statement of certain logical rules in an appropriate way, one can make do without CUT or THINNING. From the methodological point of view of this study, the logical rules ought to be framed in this newly liberalized form. These liberalized logical rules determine the system of core logic. Given any intuitionistic Gentzen proof of $\Delta:\varphi$, one can determine from it a Core proof of some subsequent of $\Delta:\varphi$. Given any classical Gentzen proof of $\Delta:\varphi$, one can determine from it a classical Core proof of some subsequent of $\Delta:\varphi$. In both cases the Core proof is of a result at least as strong as that of the Gentzen proof; and the only structural rule used is $\varphi:\varphi$. (shrink)

We show that if there is no inner model with a Woodin cardinal and the Steel core model K exists, then every Jónsson cardinal is Ramsey in K, and every δ-Jónsson cardinal is δ-Erdös in K. In the absence of the Steel core model K we prove the same conclusion for any model L[E] such that either V = L[E] is the minimal model for a Woodin cardinal, or there is no inner model with a Woodin cardinal and (...) V is a generic extension of L[E]. The proof includes one lemma of independent interest: If V = L[A], where A $\subset$ κ and κ is regular, then L κ [A] is a Jónsson algebra. The proof of this result, Lemma 2.5, is very short and entirely elementary. (shrink)

We show that if there is no inner model with a Woodin cardinal and the Steel core model K exists, then every Jonsson cardinal is Ramsey in K, and every $\delta$-Jonsson cardinal is $\delta$-Erdos in K. In the absence of the Steel core model K we prove the same conclusion for any model L$[\mathscr{E}]$ such that either V = L$[\mathscr{E}]$ is the minimal model for a Woodin cardinal, or there is no inner model with a Woodin cardinal and (...) V is a generic extension of L$[\mathscr{E}]$. The proof includes one lemma of independent interest: If V = L$[\mathscr{A}]$, where A $\subset$ $\kappa$ and $\kappa$ is regular, then L$_\kappa$[A] is a Jonsson algebra. The proof of this result, Lemma 2.5, is very short and entirely elementary. (shrink)

Reviews in Common Knowledge generally seek to be more cool and edgy than their subjects, an impossibility in this case. Ording takes a mathematical statement and reaches it in ninety-nine different ways. This book is quite literally a page-turner: most of the arguments take the recto page, with comments on their verso. One keeps cycling back and forth between the mathematical inventiveness of the recto and the philosophical elegance of the verso. The ambition is huge—to construct a mathematical counterpart to (...) Queneau's masterpiece Exercises de Style—and, remarkably, this ambition is fulfilled.It is interesting that Queneau's variations are much closer to each other than Ording's are. Queneau often feels free to provide, as a variation, the very same text with a fundamentally grammatical transformation (switching the order of the descriptions, changing their tenses, and so forth). Most of the time, Ording feels obliged to come up with a significantly different argument. Indeed, his fixed core is less constraining: instead of following the same narrative arc in different forms, he merely has to reach the same endpoint. Ording's book is rather like ninety-nine different jokes leading to the same punch line. To be clear: it is perfectly possible to produce the precise same narrative arc, in mathematics, via different forms. Switching the order is a normal way in which such exercises in mathematical style are actually produced (mathematicians do have to decide whether to write “P, therefore Q” or to write “Q, since P”). Evidently, Ording felt that producing many such purely grammatical and formal transformations would feel tedious, which is fair enough but is not precisely a contrast between mathematics and literature. Queneau's variations are, indeed, tedious; delightfully tedious; delightful in their tediousness. Joyce as a tasting menu. Some readers of modernist literature can take delight in a certain tediousness, but Ording has no illusions concerning the audience for mathematics, and, to make his own variations appealing, he had to make them much more interesting than Queneau's. The result is brilliant and should be read by anyone interested in mathematics, literature, and their many parallels and variations. (shrink)

This paper considers one of the most significant and controversial attempts to account for the meaning of pejoratives as lexical items, namely Hom and May’s. After outlining the theory, we pinpoint sets of pejorative sentences that come out true on their account and for which the question as to whether they are compatible with the view advocated by them (so-called Moral and Semantic Innocence) remains open. Helping ourselves to the standard model-theoretical framework Hom and May (presumably) work in, we prove (...) they are compatible with the view. Given that the issues of both the moral import of pejoratives and the practical effects of their utterance are not settled by the proof, we then highlight unwelcome moral and pragmatic implications for some of the pejorative sentences under scrutiny, thereby showing that the view, broadly understood, is not as morally and semantically innocuous as it is meant to be. (shrink)

This study looks at the position of two of the Middle Ages’ towering intellectual figures, Avicenna and Aquinas, and their arguments concerning the age of the cosmos. The primary focus is the nature of possibility and whether possibility is such that God can create it or such that its “existence” has some degree of independence from God’s creative act. It is shown how one’s answer to this initial question in turn has enormous ramifications on a number of other, core (...) theological topics. These issues include one’s position concerning whether the cosmos necessarily existed infinitely into the past or may have been created at some finite point in the past; how one understands divine simplicity; what constitutes omnipotence; and even the place of rhetoric in theological and philosophical discussions. (shrink)

The ethics of research on human subjects is often construed as a fine balance between the interests of patients in need of novel health interventions, and those of study participants who should remain safe in the process. But there is a third group in the mix. Some people belong to neither category, yet research can affect or jeopardize them. Call such people “bystanders.” This article shows that thinking about bystander protection can question whether there is an upper limit on the (...) risks that studies may legitimately visit upon their participants. Thus, thinking about appropriate bystander protection can shed light on the appropriate protection of study participants. Core research ethics, which focuses on the latter, must consider the former as well. (shrink)

In a society where mobility, globalization and contact with people from other cultures have become its basic descriptors, the enhancement of plurilingualism and intercultural understanding seem to be of the utmost concern. From a Positive Psychology Perspective, agency is the human capacity to affect other people positively or negatively through their actions. This agentic vision can be related to mediation, a concept rooted in the socio-cultural learning theory where social interaction is considered a fundamental cornerstone in the development of cognition. (...) Social interactions in the language learning setting may be facilitated through musical activities due to its social bonding effect. This paper tries to offer insights on how a musical-mediated experience in language learning may develop students’ interpersonal and collaborative competences to become active members of a more inclusive society. Mediation, considered as a paradigm shift in the foreign language classroom and the different out-of-class language learning possibilities, could also provide an environment where learners maximize their emotional intelligence. Our paper focuses on this paradigm shift spearheaded by the CEFR Companion Volume and the considerable repercussions it is bound to have for foreign language didactics, as cooperative tasks become central to foreign language learning. We hypothesize that mediated language learning experiences imply a socioemotional change in learners, focusing on the others, on their needs and interests, by trying to help them understand texts, concepts or facilitating communication with their peers. An intervention with a musical-mediated language learning experience was designed and implemented in the classroom. A self assessment scale with mediation descriptors and the socioemotional expertise scale (SEE) were administered. Results show that students become more mindful of their strengths, of their capacity for collaborating and team working. This leads to more awareness of their mediation skills. Students’ mediation skills correlate significantly with their socio-emotional skills, more concretely with their expressivity. The implementation of a musical-mediated experience also promoted tolerance and enhanced learners’ intrinsic motivation for language learning at the same time as they acknowledged their diversity. (shrink)

Philosophical Investigations, Volume 44, Issue 4, Page 403-425, October 2021.

Ethics consultation has become an integral part of the fabric of U.S. health care delivery. This article summarizes the second edition of the Core Competencies for Health Care Ethics Consultation report of the American Society for Bioethics and Humanities. The core knowledge and skills competencies identified in the first edition of Core Competencies have been adopted by various ethics consultation services and education programs, providing evidence of their endorsement as health care ethics consultation (HCEC) standards. This revised (...) report was prompted by thinking in the field that has evolved since the original report. Patients, family members, and health care providers who encounter ethical questions or concerns that ethics consultants could help address deserve access to efficient, effective, and accountable HCEC services. All individuals providing such services should be held to the standards of competence and quality described in the revised report. (shrink)

A short core model induction proof of $\mathsf {AD}^{L(\mathbb {R})}$ from $\mathsf {TD} + \mathsf {DC}_{\mathbb {R}}$.

An interview with Charles McCarty by Piotr Urbańczyk concerning mathematical explanation.

Bilateralists hold that the meanings of the connectives are determined by rules of inference for their use in deductive reasoning with asserted and denied formulas. This paper presents two bilateral connectives comparable to Prior's tonk, for which, unlike for tonk, there are reduction steps for the removal of maximal formulas arising from introducing and eliminating formulas with those connectives as main operators. Adding either of them to bilateral classical logic results in an incoherent system. One way around this problem is (...) to count formulas as maximal that are the conclusion of reductio and major premise of an elimination rule and to require their removability from deductions. The main part of the paper consists in a proof of a normalisation theorem for bilateral logic. The closing sections address philosophical concerns whether the proof provides a satisfactory solution to the problem at hand and confronts bilateralists with the dilemma that a bilateral notion of stability sits uneasily with the core bilateral thesis. (shrink)