This text is an outgrowth of notes prepared by J. Y. Girard for a course at the University of Paris VII. It deals with the mathematical background of the application to computer science of aspects of logic (namely the correspondence between proposition & types). Combined with the conceptual perspectives of Girard's ideas, this sheds light on both the traditional logic material & its prospective applications to computer science. The book covers a very active & exciting research area, & it will (...) be essential reading for all those working in logic & computer science. (shrink)
ABSTRACTDo truth tables—the ordinary sort that we use in teaching and explaining basic propositional logic—require an assumption of consistency for their construction? In this essay we show that truth tables can be built in a consistency-independent paraconsistent setting, without any appeal to classical logic. This is evidence for a more general claim—that when we write down the orthodox semantic clauses for a logic, whatever logic we presuppose in the background will be the logic that appears in the foreground. Rather than (...) any one logic being privileged, then, on this count partisans across the logical spectrum are in relatively similar dialectical positions. (shrink)
We present four classical theories of counterpossibles that combine modalities and counterfactuals. Two theories are anti-vacuist and forbid vacuously true counterfactuals, two are quasi-vacuist and allow counterfactuals to be vacuously true when their antecedent is not only impossible, but also inconceivable. The theories vary on how they restrict the interaction of modalities and counterfactuals. We provide a logical cartography with precise acceptable boundaries, illustrating to what extent nonvacuism about counterpossibles can be reconciled with classical logic.
It has been an open question whether or not we can define a belief revision operation that is distinct from simple belief expansion using paraconsistent logic. In this paper, we investigate the possibility of meeting the challenge of defining a belief revision operation using the resources made available by the study of dynamic epistemic logic in the presence of paraconsistent logic. We will show that it is possible to define dynamic operations of belief revision in a paraconsistent setting.
This paper presents a new modal logic for ceteris paribus preferences understood in the sense of "all other things being equal". This reading goes back to the seminal work of Von Wright in the early 1960's and has returned in computer science in the 1990' s and in more abstract "dependency logics" today. We show how it differs from ceteris paribus as "all other things being normal", which is used in contexts with preference defeaters. We provide a semantic analysis and (...) several completeness theorems. We show how our system links up with Von Wright's work, and how it applies to game-theoretic solution concepts, to agenda setting in investigation, and to preference change. We finally consider its relation with infinitary modal logics. (shrink)
In this paper we explore the relationship between norms of belief revision that may be adopted by members of a community and the resulting dynamic properties of the distribution of beliefs across that community. We show that at a qualitative level many aspects of social belief change can be obtained from a very simple model, which we call ‘threshold influence’. In particular, we focus on the question of what makes the beliefs of a community stable under various dynamical situations. We (...) also consider refinements and alternatives to the ‘threshold’ model, the most significant of which is to consider changes to plausibility judgements rather than mere beliefs. We show first that some such change is mandated by difficult problems with belief-based dynamics related to the need to decide on an order in which different beliefs are considered. Secondly, we show that the resulting plausibility-based account results in a deterministic dynamical system that is non-deterministic at the level of beliefs. (shrink)
In _Battling to the End _René Girard engages Carl von Clausewitz, the Prussian military theoretician who wrote _On War_. Clausewitz, who has been critiqued by military strategists, political scientists, and philosophers, famously postulated that "War is the continuation of politics by other means." He also seemed to believe that governments could constrain war. Clausewitz, a firsthand witness to the Napoleonic Wars, understood the nature of modern warfare. Far from controlling violence, politics follows in war's wake: the means of war have (...) become its ends. René Girard shows us a Clausewitz who is a fascinated witness of history's acceleration. Haunted by the French-German conflict, Clausewitz clarifies more than anyone else the development that would ravage Europe. _Battling to the End _pushes aside the taboo that prevents us from seeing that the apocalypse has begun. Human violence is escaping our control; today it threatens the entire planet. (shrink)
L’objection la plus ancienne et la plus redoutable à la démocratie fait valoir que le gouvernement par le peuple dessert le gouvernement pour le peuple. Les citoyens manquant pour la plupart de sagesse ou de compétence, le bien commun serait mieux assuré en confiant le pouvoir à un individu éclairé ou à une élite experte. Une réponse commune à cette objection concède la prémisse mais affirme la priorité au gouvernement par le peuple sur le gouvernement pour le peuple : le (...) droit égal à la participation devrait l’emporter sur la promotion de la compétence, même si celle-ci est requise par le bon gouvernement. La démocratie se trouve alors réduite à un ensemble de procédures équitables, traitant les citoyens en égaux ; elle ne se définit plus par la poursuite du bien commun. Il est toutefois une autre réponse à l’objection, qui évite cette dérive vers un procéduralisme étroit. Elle consiste à nier la prémisse et à affirmer la sagesse politique du peuple. Il n’est pas vrai que le gouvernement pour le peuple serait mieux assuré en confiant le pouvoir à un petit nombre de sages ou d’experts, fussent-ils les meilleurs parmi les citoyens. Cette thèse remarquable peut paraître improbable. Sa défense peut pourtant s’appuyer sur l’un des arguments les plus intrigants élaborés par la philosophie politique aristotélicienne, qui inspire et éclaire les controverses philosophiques contemporaines sur la valeur du régime démocratique : l’argument de la sagesse de la multitude. (shrink)
Standard reasoning about Kripke semantics for modal logic is almost always based on a background framework of classical logic. Can proofs for familiar definability theorems be carried out using a nonclassical substructural logic as the metatheory? This article presents a semantics for positive substructural modal logic and studies the connection between frame conditions and formulas, via definability theorems. The novelty is that all the proofs are carried out with a noncontractive logic in the background. This sheds light on which modal (...) principles are invariant under changes of metalogic, and provides evidence for the general viability of nonclassical mathematics. (shrink)
This article maintains that an important class of scientific generalizations should be reinterpreted: they have typically been understood as ceteris paribus laws, but are, in fact, generics. Four arguments are presented to support this thesis. One argument is that the interpretation in terms of ceteris paribus laws is a historical accident. The other three arguments draw on similarities between these generalizations and archetypal generics: they come with similar inferential commitments, they share a syntactic form, and the existing theories to make (...) sense of them are alike. Once these generalizations are properly understood as generics, the recent cognitive approach to generics can be extended to the study of the relevant sciences. The last section indicates ways in which this extension is fruitful for the two strands of research that we combine: the philosophy of science literature on generalizations and the semantics literature on generics. (shrink)
The idea of relevant logic—that irrelevant inferences are invalid—is appealing. But the standard semantics for relevant logics involve baroque metaphysics: a three-place accessibility relation, a star operator, and ‘bad’ worlds. In this article we propose that these oddities express a mismatch between non-classical object theory and classical metatheory. A uniformly relevant semantics for relevant logic is a better fit.
We present a single sequent calculus common to classical, intuitionistic and linear logics. The main novelty is that classical, intuitionistic and linear logics appear as fragments, i.e. as particular classes of formulas and sequents. For instance, a proof of an intuitionistic formula A may use classical or linear lemmas without any restriction: but after cut-elimination the proof of A is wholly intuitionistic, what is superficially achieved by the subformula property and more deeply by a very careful treatment of structural rules. (...) This approach is radically different from the one that consists in “changing the rule of the game” when we want to change logic, e.g. pass from one style of sequent to another: here, there is only one logic, which—depending on its use—may appear classical, intuitionistic or linear. (shrink)
These lectures on logic, more specifically proof theory, are basically intended for postgraduate students and researchers in logic. The question at stake is the nature of mathematical knowledge and the difference between a question and an answer, i.e., the implicit and the explicit. The problem is delicate mathematically and philosophically as well: the relation between a question and its answer is a sort of equality where one side is ``more equal than the other'': one thus discovers essentialist blind spots. Starting (...) with Godel's paradox --so to speak, the incompleteness of answers with respect to questions--the book proceeds with paradigms inherited from Gentzen's cut-elimination. Various settings are studied: sequent calculus, natural deduction, lambda calculi, category-theoretic composition, up to geometry of interaction, all devoted to explicitation, which eventually amounts to inverting an operator in a von Neumann algebra. Mathematical language is usually described as referring to a preexisting reality. Logical operations can be given an alternative procedural meaning: typically, the operators involved in GoI are invertible, not because they are constructed according to the book, but because logical rules are those ensuring invertibility. Similarly, the durability of truth should not be taken for granted: one should distinguish between imperfect and perfect modes. The procedural explanation of the infinite thus identifies it with the unfinished, i.e., the perennial. But is perenniality perennial? This questioning yields a possible logical explanation for algorithmic complexity. This highly original course on logic by one of the world's leading proof theorists challenges mathematicians, computer scientists, physicists, and philosophers to rethink their views and concepts on the nature of mathematical knowledge in an exceptionally profound way. (shrink)
The semantics for counterfactuals due to David Lewis has been challenged by appealing to miracles. Miracles may skew a given similarity order in favour of those possible worlds which exhibit them. Lewis responded with a system of priorities that mitigates the significance of miracles when constructing similarity relations. We propose a prioritised ceteris paribus analysis of counterfactuals inspired by Lewis’ system of priorities. By analysing the couterfactuals with a ceteris paribus clause one forces out, in a natural manner, those possible (...) worlds which do not satisfy the requirements of the clause, thus excluding miracles. If no world can satisfy the ceteris paribus clause in its entirety, then prioritisation is triggered to select worlds that maximise agreement on those things which are favoured most. (shrink)
Maintes philosophies contemporaines de la démocratie s’accordent pour donner à la délibération publique une place centrale dans la prise de décisions politiques légitimes. Cet accord masque toutefois un désaccord récurrent sur la source de sa valeur : elle est liée, selon les théories, à son effet sur les participants, à sa valeur expressive, à son équité ou encore à la qualité des décisions qu’elle produit. Ces visions concurrentes de la délibération démocratique ont des implications différentes et parfois contradictoires pour les (...) pratiques et les institutions politiques. Cet article analyse ces justifications afin d’en éprouver la solidité et de clarifier leurs relations. Il défend une justification originale de la délibération démocratique, en montrant qu’elle traite équitablement les citoyens en tant qu’auditeurs, donc en tant que juges. S’il n’est pas sûr qu’elle favorise en général la prise de bonnes décisions, elle rend moins inégales les conditions sous lesquelles les citoyens peuvent porter un jugement politique. Many contemporary philosophies of democracy agree that public deliberation plays an essential role in the making of legitimate political decisions. However, this consensus masks significant disagreement concerning the exact source of its value, as it is alternatively located in its impact on participants, in its expressive value, in its fairness, or in the quality of the decisions it produces. These rival justifications of democratic deliberation have different, and sometimes contradictory, consequences for political practices and institutions. This article analyses these justifications to decide between them and to clarify how they relate to each other. It develops an original justification of democratic deliberation by showing that it treats citizens fairly as listeners if not speakers. While it is not certain that democratic deliberation makes it in general more likely to reach a good decision, it makes the conditions for political judgement less unequal. (shrink)
Previously we reported a three-factor structure for hallucinations accompanying sleep paralysis . These earlier analyses were, however, based on retrospective accounts. In a prospective study, 383 individuals reported individual episodes online providing further evidence for the three-factor structure as well as clearer conceptually meaningful relations among factors than retrospective studies. In addition, reports of individual episodes permitted a more fine-grained analysis of the internal structure of factors to assess predictions based on the hypothesis that a sensed or felt presence is (...) a core experience affecting other SP hallucinations. Results were generally consistent with this hypothesis. In particular, associations among, and temporal stability of, sensory hallucinations were largely explained by their common association with FP. The findings are consistent with REM initiation of a threat activated vigilance system with pervasive effects on the SP experience and suggest a potential model for the thematic organization of nightmares and dreams more generally. (shrink)
Hervaeus Natalis distinguishes two types of items that can have esse obiective in the intellect: objects of acts of intellection (man, this cat, etc.) and properties unapprehended by these acts, or background properties (being a species, being a particular, etc.), that are beings of reason. Yet, his conception of the esse obiective of objects evolved. First, he had a neutral conception of esse obiective: items presenting themselves to the intellect are cognized, transparently, without being altered in the process. Later, he (...) developed an ontologically committing conception of the objective being of objects: items presenting themselves to the intellect take on rational being (esse rationis) as such. This evolution transpires because Hervaeus introduces intentional relations as what makes the cognized item be objectively in the intellect and includes them within the class of background properties (being of reason). Both these conceptions manage to account for our access to extra-mental things. -/- . (shrink)
L’idéal démocratique est accusé d’être irréaliste. Le gouvernement du peuple par le peuple et pour le peuple serait une chimère dans les sociétés contemporaines. Il faudrait lui préférer les visées plus modestes associées à l’élection : un droit de vote égal et la satisfaction du plus grand nombre. La démocratie ne se laisse pourtant pas réduire à la compétition électorale. Les acteurs et les institutions politiques qui s’en réclament invoquent non seulement un marché, où rivalisent des intérêts privés, mais un (...) forum, où s’affrontent des visions adverses de la justice. Ils attendent de la délibération collective qu’elle serve l’autonomie politique et le bien commun, mais savent aussi qu’elle peut les menacer, lorsque la liberté, l’égalité ou la publicité lui font défaut. Cette enquête philosophique interroge la pertinence de l’idéal démocratique pour des sociétés complexes, dotées d’institutions représentatives et soumises à la communication de masse. Elle montre à quelles conditions cet idéal peut aujourd’hui orienter la critique et l’action. Les citoyens peuvent encore aspirer à se gouverner eux-mêmes, donc à délibérer en égaux. -/- The democratic ideal is accused of being unrealistic. Government of the people by the people and for the people would be a chimera in contemporary societies. The more modest aims associated with election should be preferred: equal suffrage and the satisfaction of the greatest number. But democracy cannot be reduced to electoral competition. The political actors and institutions that claim it invoke not only a market, where private interests compete, but also a forum, where opposing visions of justice confront each other. They expect collective deliberation to serve political autonomy and the common good, but they also know that it can threaten them when it lacks freedom, equality or publicity. This philosophical inquiry questions the relevance of the democratic ideal for complex societies with representative institutions and subject to mass communication. It shows under what conditions a deliberative understanding of this ideal can today orient criticism and action. Citizens can still aspire to govern themselves, hence to deliberate as equals. (shrink)
The aim of this article is to develop a new classification of stakeholders based on the concept of corporate and social engagement. Engagement is analyzed as an organizational learning process between the managers of an organization and its stakeholders. It is a necessary condition to improve the organization’s impact on its economic, social, and natural environment. Applied to the membership of a French mutual bank in order to identify the members’ varying levels of engagement, this new mapping technique may help (...) managers to adapt their practices to the degree of engagement of each identified group of members, and to modify their financial products and communications to foster engagement among as many of these groups as possible. (shrink)
This paper is a step toward showing what is achievable using non-classical metatheory—particularly, a substructural paraconsistent framework. What standard results, or analogues thereof, from the classical metatheory of first order logic can be obtained? We reconstruct some of the originals proofs for Completeness, Löwenheim-Skolem and Compactness theorems in the context of a substructural logic with the naive comprehension schema. The main result is that paraconsistent metatheory can ‘re-capture’ versions of standard theorems, given suitable restrictions and background assumptions; but the shift (...) to non-classical logic may recast the meanings of these apparently ‘absolute’ theorems. (shrink)
Investigation of “out-of-body experiences” has implications for understanding both normal bodily-self integration and its vulnerabilities. Beyond reported associations between OBEs and specific brain regions, however, there have been few investigations of neurochemical systems relevant to OBEs. Ketamine, a drug used recreationally to achieve dissociative experiences, provides a real-world paradigm for investigating neurochemical effects. We investigate the strength of the association of OBEs and ketamine use relative to other common drugs of abuse. Self-report data from an online survey indicate that both (...) lifetime frequency of ketamine use and OBEs during ketamine intoxication were more strongly related to the frequency of OBEs and related phenomena than other drugs. Moreover, the apparent effects of other drugs could largely be explained by associated ketamine use. The present results, consistent with the role of NMDA receptors in OBEs, should encourage future studies of the role of neurochemical systems in OBEs. (shrink)
In the late 20th century theorists within the radical feminist tradition such as Haraway highlighted the impossibility of separating knowledge from knowers, grounding firmly the idea that embodied bias can and does make its way into argument. Along a similar vein, Moulton exposed a gendered theme within critical thinking that casts the feminine as toxic ‘unreason’ and the ideal knower as distinctly masculine; framing critical thinking as a method of masculine knowers fighting off feminine ‘unreason’. Theorists such as Burrow have (...) picked up upon this tradition, exploring the ways in which this theme of overly masculine, or ‘adversarial’, argumentation is both unnecessary and serves as an ineffective base for obtaining truth. Rooney further highlighted how this unnecessarily gendered context results in argumentative double binds for women, undermining their authority and stifling much-needed diversity within philosophy as a discipline.These are damning charges that warrant a response within critical thinking frameworks. We suggest that the broader critical thinking literature, primarily that found within contexts of critical pedagogy and dispositional schools, can and should be harnessed within the critical thinking literature to bridge the gap between classical and feminist thinkers. We highlight several methods by which philosophy can retain the functionality of critical thinking while mitigating the obstacles presented by feminist critics and highlight how the adoption of such methods not only improves critical thinking, but is also beneficial to philosophy, philosophers and feminists alike. (shrink)
We present a generalization of Segerberg's onion semantics for belief revision, in which the linearity of the spheres need not occur. The resulting logic is called broccoli logic. We provide a minimal relational logic, with a bi-modal neighborhood semantics. We then show that broccoli logic is a well-known conditional logic, the Burgess-Veltman minimal conditional logic.
Cet article détaille un processus participatif mis en place sur le bassin versant de la Drôme pour préparer, avec les citoyens, la révision du Schéma d’Aménagement et de Gestion des Eaux. Spécifiquement, des citoyens ont été associés précocement pour choisir et organiser leur propre processus participatif. Cette co-ingénierie les a sensibilisés à l’importance de ces décisions, a initié des apprentissages sociaux et posé les conditions d’une régulation efficiente. Elle a clarifié les liens entre la participation et la gouvernance institutionnelle. Mais (...) l’exercice apparaît abstrait aux participants. Il requiert des règles de participation claires et une initiation aux enjeux et au vocabulaire de la participation. En conclusion, nous suggérons des adaptations de la co-ingénierie de la participation en fonction des attentes et moyens disponibles. This paper investigates a participatory process set up in the Drôme river basin to get citizens to support the updating of the water management scheme. Some citizens were engaged at an early stage in selecting and structuring their own participatory process. Such co-engineering raised their awareness about the importance of these decisions, fostered social learning and triggered conditions for an efficient regulation. It clarified the links between participation and institutional governance. But co-engineering was abstract for participants. Co-engineering requires clear participation rules and sufficient awareness of the issues and vocabulary of participation. To conclude we propose adjustments to the co-engineering of participation according to the expectations and resources available. (shrink)
Le 15 décembre 2005, René Girard, lors de son entrée à l'Académie française, prononça l'éloge de son prédécesseur, le révérend père Carré. Michel Serres répondit à ce discours par un tableau de la vie et de l'oeuvre du récipiendaire dont, dit-il, la théorie compte parmi les plus fécondes du XXe siècle.
In this lively series of conversations with writer Michel Treguer, René Girard revisits the major concepts of mimetic theory and explores science, democracy, and the nature of God and freedom. Girard affirms that “our unprecedented present is incomprehensible without Christianity.” Globalization has unified the world, yet civil war and terrorism persist despite free trade and economic growth. Because of mimetic desire and the rivalry it generates, asserts Girard, “whether we’re talking about marriage, friendship, professional relationships, issues with neighbors or matters (...) of national unity, human relations are always under threat.” Literary masters including Marivaux, Dostoevsky, and Joyce understood this, as did archaic religion, which warded off violence with blood sacrifice. Christianity brought a new understanding of sacrifice, giving rise not only to modern rationality and science but also to a fragile system that is, in Girard’s words, “always teetering between a new golden age and a destructive apocalypse.” Treguer, a skeptic of mimetic theory, wonders: “Is what he’s telling me true...or is it just a nice story, a way of looking at things?” In response, Girard makes a compelling case for his theory. (shrink)
This paper is about teaching elementary logic to blind or visually impaired students. The targeted audience are teachers who all of sudden have a blind or visually impaired student in their introduction to logic class, find limited help from disability centers in their institution, and have no idea what to do. We provide simple techniques that allow direct communication between a teacher and a visually impaired student. We show how the use of what is known as Polish notation simplifies communication, (...) and pedagogically is a great notation for a Braille reader. (shrink)
The expression conditional fallacy identifies a family of arguments deemed to entail odd and false consequences for notions defined in terms of counterfactuals. The antirealist notion of truth is typically defined in terms of what a rational enquirer or a community of rational enquirers would believe if they were suitably informed. This notion is deemed to entail, via the conditional fallacy, odd and false propositions, for example that there necessarily exists a rational enquirer. If these consequences do indeed follow from (...) the antirealist notion of truth, alethic antirealism should probably be rejected. In this paper we analyse the conditional fallacy from a semantic (i.e. model-theoretic) point of view. This allows us to identify with precision the philosophical commitments that ground the validity of this type of argument. We show that the conditional fallacy arguments against alethic antirealism are valid only if controversial metaphysical assumptions are accepted. We suggest that the antirealist is not committed to the conditional fallacy because she is not committed to some of these assumptions. (shrink)