Recently logic has shifted emphasis from static systems developed for purely theoretical reasons to dynamic systems designed for application to real world situations. The emphasis on the applied aspects of logic and reasoning means that logic has become a pragmatic tool, to be judged against the backdrop of a particular application. This shift in emphasis is, however, not new. A similar shift towards “interactive logic” occurred in the high Middle Ages. We provide a number of different examples of “interactive logic” (...) in the Middle Ages, all species of the disputation game obligatio. These games display a recognition of the importance of interaction in logical contexts and the way that interactive logic differs from single-agent inference. (shrink)

Formal dialogue systems model rule-based interaction between agents and as such have multiple applications in multi-agent systems and AI more generally. Their conceptual roots are in formal theories of natural argumentation, of which Hamblin’s formal systems of argumentation in Hamblin (Fallacies. Methuen, London, 1970, Theoria 37:130–135, 1971) are some of the earliest examples. Hamblin cites the medieval theory of obligationes as inspiration for his development of formal argumentation. In an obligatio, two agents, the Opponent and the Respondent, engage in an (...) alternating-move dialogue, where the Respondent’s actions are governed by certain rules, and the goal of the dialogue is establishing the consistency of a proposition. We implement obligationes in the formal dialogue system framework of Prakken (Knowl Eng Rev 21(2):163–188, 2006) using Dynamic Epistemic Logic (van Ditmarsch et al. in Dynamic epistemic logic, Synthese Library Series. Springer, Berlin, 2007). The result is a new type of inter-agent dialogue, for consistency-checking, and analyzing obligationes in this way also sheds light on interpretational and historical questions concerning their use and purpose in medieval academia. (shrink)

This dissertation is an analysis of the development of dialectic and argumentation theory in post-classical Islamic intellectual history. The central concerns of the thesis are; treatises on the theoretical understanding of the concept of dialectic and argumentation theory, and how, in practice, the concept of dialectic, as expressed in the Greek classical tradition, was received and used by five communities in the Islamic intellectual camp. It shows how dialectic as an argumentative discourse diffused into five communities (theologicians, poets, grammarians, philosophers (...) and jurists) and how these local dialectics that the individual communities developed fused into a single system to form a general argumentation theory (adab al-bahth) applicable to all fields. I evaluate a treatise by Shams al-Din Samarqandi (d.702/1302), the founder of this general theory, and the treatises that were written after him as a result of his work. I concentrate specifically on work by Adud al-Din al-Iji (d.756/1355), Sayyid Sharif al-Jurjani (d.816/1413), Taşköprüzâde (d.968/1561), Saçaklızâde (d.1150/1737) and Gelenbevî (d.1205/1791) and analyze how each writer (from Samarqandi to Gelenbevî) altered the shape of argumentative discourse and how later intellectuals in the post-classical Islamic world responded to that discourse bequeathed by their predecessors. What is striking about the period that this dissertation investigates (from 1300-1800) is the persistence of what could be called the linguistic turn in argumentation theory. After a centuries-long run, the jadal-based dialectic of the classical period was displaced by a new argumentation theory, which was dominantly linguistic in character. This linguistic turn in argumentation dates from the final quarter of the fourteenth century in Iji's impressively prescient work on 'ilm al-wad'. This idea, which finally surfaced in the post-classical period, that argumentation is about definition and that, therefore, defining is the business of language—even perhaps, that language is the only available medium for understanding and being understood—affected the way that argumentation theory was processed throughout most of the period in question. The argumentative discourse that started with Ibn al-Rawandi in the third/ninth century left a permanent imprint on Islamic intellectual history, which was then full of concepts, terminology and objectives from this discourse up until the late nineteenth century. From this perspective, Islamic intellectual history can be read as the tension between two languages: the "language of dialectic" (jadal) and the "language of demonstration" (burhan), each of which refer not only to a significant feature of that history, but also to a feature that could dramatically alter the interpretation of that history. (shrink)

Why did Frege offer only proper names as examples of presupposition triggers? Some scholars claim that Frege simply did not care about the full range of presuppositional phenomena. This paper argues, in contrast, that he had good reasons for employing an extremely narrow notion of ‘Voraussetzung’. On Frege’s view, many devices that are now construed as presupposition triggers either express several thoughts at once or merely ‘illuminate’ a thought in a particular way. Fregean presuppositions, in contrast, are essentially tied to (...) names. (shrink)

La lógica de la Edad Media se presenta a los lógicos contemporáneos, filósofos medievalistas, historiadores y filósofos de la lógica, como un campo tan fascinante como de difícil acceso. Parece demasiado intrincado para casi cualquier investigador de estas áreas encontrar la punta del ovillo que lo conduzca a transitar una presentación ordenada e inteligible de la lógica medieval. Este libro pretende solucionar este problema. Para ello, presenta de manera ordenada y autocontenida los desarrollos lógicos de la parte técnicamente más evolucionada (...) de la lógica de la Edad Media: el siglo XIV. A diferencia de otras presentaciones no evade los hechos históricos y culturales que conforman el panorama de la época ni las cuestiones filosóficas detrás de los desarrollos lógicos, a fin de entender cabalmente las cuestiones técnicas y no desnaturalizar la propuesta medieval. Los primeros tres capítulos se abocan a cuestiones introductorias, históricas y a la genealogía de los tópicos más importantes. El cuarto capítulo está dedicado a la presentación sintáctica del lenguaje de la lógica medieval. El quinto y el sexto a la metateoría de esta lógica. El séptimo explora y presenta la semántica. Los dos últimos nos brindan una reconstrucción racional, en términos del lenguaje simbólico contemporáneo, de la lógica de finales del siglo XIV. (shrink)

1. Something strange commenced to happen in the field of logic from the beginning of the seventeenth century. Oral disputation, rather than falling into oblivion as a relic of medieval darkness wit...

We reconsider the pragmatic interpretation of intuitionistic logic [21] regarded as a logic of assertions and their justi cations and its relations with classical logic. We recall an extension of this approach to a logic dealing with assertions and obligations, related by a notion of causal implication [14, 45]. We focus on the extension to co-intuitionistic logic, seen as a logic of hypotheses [8, 9, 13] and on polarized bi-intuitionistic logic as a logic of assertions and conjectures: looking at the (...) S4 modal translation, we give a de nition of a system AHL of bi-intuitionistic logic that correctly represents the duality between intuitionistic and co-intuitionistic logic, correcting a mistake in previous work [7, 10]. A computational interpretation of cointuitionism as a distributed calculus of coroutines is then used to give an operational interpretation of subtraction.Work on linear co-intuitionism is then recalled, a linear calculus of co-intuitionistic coroutines is de ned and a probabilistic interpretation of linear co-intuitionism is given as in [9]. Also we remark that by extending the language of intuitionistic logic we can express the notion of expectation, an assertion that in all situations the truth of p is possible and that in a logic of expectations the law of double negation holds. Similarly, extending co-intuitionistic logic, we can express the notion of conjecture that p, de ned as a hypothesis that in some situation the truth of p is epistemically necessary. (shrink)

In 1980 L. M. de Rijk edited some texts connected with medieval disputation ( Die mittelaterlichen Traktate De modo opponendi et respondendi ), towards which he showed a strikingly contemptuous attitude. The reason for his contempt was that the treatises did not fit the obligationes and sophismata tradition. In this article I focus on the original version, the Thesaurus Philosophorum , to highlight the distinction of this family of treatises with respect to the “modern“ tradition. First, I study the features (...) of the disputation that can be recognised through the collection of fallacious arguments contained in the Thesaurus . Second, I briefly examine the contents of the treatise and their arrangement, showing that they are closely related to the kind of disputation in question. I hope to support the idea that neither the technique of disputation nor the contents and their arrangement deserve a straightforward rejection. (shrink)

An obligation, in the sense in which it was of interest to medieval logicians from about the early thirteenth century to the end of the scholastic period, is, according to Paul of Venice, a relation limiting one to take some statement affirmatively or negatively. This relation is based on the actions of two individuals: one obligates the other by first putting forward a sentence which the respondent agrees to affirm or deny for a limited time. The sentence the respondent agrees (...) to affirm is called the positum; that which he agrees to deny, the depositum; and his act of agreeing, the admissio. After this relation is established between the opponent and respondent, the opponent proceeds by putting forward a series of sentences to which the respondent replies by granting, denying, or doubting — all in accordance with certain rules the two individuals have previously accepted as governing their exchange. If the respondent at any time grants what is inconsistent with the sentence he agreed to uphold, or responds in a way that violates the accepted rules, the exchange comes to an end. The respondent has failed in his obligation. (shrink)

El objetivo de este artículo es poner atención a una concepción desacreditada de la dialéctica, que pretendió recrear la consideración de Aristóteles. El artículo enfatiza el trasfondo filosófico del arte de obtener lo mejor de un oponente en disputa de Schopenhauer, e identifica especialmente tanto las viejas reglas griegas de discusión como los problemas positivos y originales de esta consideración moderna.

Only recently have scholars again taken serious interest in works on disputation in the history of logic. Several recent studies have been done on the medieval and late medieval ars obligatoria, which I would venture to say, is the best known area in the history of disputation theory. Other areas in the history of disputation theory have not been sufficiently researched, including Book VIII of the Aristotelian Topics. But no period so rich in works on disputation has been more neglected (...) by modern scholarship than the period from the mid-16th century to the mid-18th century. This dissertation is a critical historical study of logic books and dissertations published between the mid-16th century to the late 18th century on methods and techniques of disputation; it thus aims to partially fill this gap in our knowledge of the history of logic. The study focuses for the most part on a substantial body of little-known logic literature by German second scholastic logicians, such as Keckermann, Johannes Dannhawerus, Jacobus Thomasius, and Andreas Kesler, to name a few. Some discussion of Leibnizian fragments on the ars disputandi is also presented. Topics treated in the dissertation include the aims and structure of post-medieval disputation, particular rules and strategies, and such topics as the logical force of various disputation moves and rules governing onus probandi. (shrink)

The article deals with the Lutheran–Catholic religious colloquy at Regensburg of 1601. It points out that the event was of importance not only for political and religious reasons but also in terms...

Este artículo se propone reconstruir histórica y metodológicamente la disputatio scholastica y acercarse a la manera como era ejercitado este tipo de juego dialéctico en los colegios jesuitas de la América Hispánica. Examinando fuentes manuscritas e impresas, se enumeran y discuten las reglas que los participantes de los certámenes filosóficos de la escolástica barroca obedecían. La estructura lógica y dialéctica de la disputatio es examinada a la luz del método de discusión abstraído y sistematizado por Aristóteles en los Tópicos. Se (...) destaca el lugar privilegiado de la capacidad de distinguir sentidos como instrumento de la dialéctica en la disputatio scholastica. (shrink)

This collection of papers, celebrating the contributions of Swedish logician Dag Prawitz to Proof Theory, has been assembled from those presented at the Natural Deduction conference organized in Rio de Janeiro to honour his seminal research. Dag Prawitz’s work forms the basis of intuitionistic type theory and his inversion principle constitutes the foundation of most modern accounts of proof-theoretic semantics in Logic, Linguistics and Theoretical Computer Science. The range of contributions includes material on the extension of natural deduction with higher-order (...) rules, as opposed to higher-order connectives, and a paper discussing the application of natural deduction rules to dealing with equality in predicate calculus. The volume continues with a key chapter summarizing work on the extension of the Curry-Howard isomorphism, via methods of category theory that have been successfully applied to linear logic, as well as many other contributions from highly regarded authorities. With an illustrious group of contributors addressing a wealth of topics and applications, this volume is a valuable addition to the libraries of academics in the multiple disciplines whose development has been given added scope by the methodologies supplied by natural deduction. The volume is representative of the rich and varied directions that Prawitz work has inspired in the area of natural deduction. (shrink)

This paper contributes to the calculization of evocation and erotetic implication as defined by Inferential Erotetic Logic (IEL). There is a straightforward approach to calculizing (propositional) erotetic implication which cannot be applied to evocation. First-order evocation is proven to be uncalculizable, i.e. there is no proof system, say FOE, such that for all X, Q: X evokes Q iff there is an FOE-proof for the evocation of Q by X. These results suggest a critique of the represented approaches to calculizing (...) IEL. This critique is expanded into a programmatic reconsideration of the IEL-definitions of evocation and erotetic implication. From a different point of view these definitions should be seen as desiderata that may or may not play the role of a point of orientation when setting up "rules of asking". (shrink)

As Redes Dialéticas visam a representação dos elementos de uma disputa: as asserções do Proponente e do Oponente, e as ações de ataque e de defesa. Proponho uma representação diagramática – o Diagrama Dialético – e uma representação algébrica – o Grafo Dialético – das Redes Dialéticas. Este trabalho está limitado aos aspectos estático-estruturais das Redes Dialéticas.