Logica Universalis - Join the Logica Universalis Webinar 2024!
The Logica Universalis Webinar is a World Seminar Series connected to the journal Logica Universalis (this opens in a new tab), the book series Studies in Universal Logic (this opens in a new tab) and the Universal Logic Project (this opens in a new tab). It is an open platform for all scholars interested in the many aspects of logic. The project started in 2021. Click here (this opens in a new tab) to access the webinar series of past editions.
The LUW 2024 series starts with an "extraordinary" session: LUA celebration of the sixth World Logic Day. The celebration will be held from Cusco (Peru) during SALOME 1 (this opens in a new tab): the first South American LOgic MEeting, Jan 14, 2024.
The sessions take place on Wednesdays at 4pm CET. They are held via Zoom through the platform Cassyni and are free to attend. Please register and subscribe in advance.
Registration is now open! (this opens in a new tab)
Please note that you will be required to register before subscribing to the webinar series. You will be automatically directed to the registration page or click here (this opens in a new tab).
Video recordings of the seminars are uploaded on the Cassyni platform (this opens in a new tab).
Each session of the webinar is chaired by a member of the editorial board of the journal Logica Universalis (LU), the book series Studies in Universal Logic (SUL) or an organizer of an event of the Universal Logic Project (ULP). Sessions will start with a short presentation of a logical organization related to the region of the speaker or the topic of the talk. The talk (30 min) will focus on a recently published paper in LU, on a book in SUL, on an event or on the ULP. Talks are followed by a discussion (15 min).
Webinar Schedule
Speakers and Abstracts
February 14, 2024 – Til Eyinck (this opens in a new tab) (University of Cologne, Germany) –
Should We Embrace Impossible Worlds Due to the Flaws of Normal Modal Logic? (this opens in a new tab)
Chair: Ahti-Veikko Pietarinen (this opens in a new tab), Editorial Board LU
Associate Organization: Women in Focus. Rethinking Philosophy and History of Mathematics and Physics (this opens in a new tab) presented by Jasmin Özel (this opens in a new tab)
Some philosophers advance the claim that the phenomena of logical omniscience and of the indiscernibility of metaphysical statements, which arise in (certain) interpretations of normal modal logic, provide strong reasons in favour of impossible world approaches. These two specific lines of argument will be presented and discussed in this paper. Contrary to the recent much-held view that the characteristics of these two phenomena provide us with strong reasons to adopt impossible world approaches, the view defended here is that no such ‘knock-down arguments’ do emanate on those grounds. This is not to rule out that there cannot be any other good reasons for assuming impossible world semantics. However, the discussion of a further argument for impossible worlds will suggest that different attempts to argue for them likely present intertwined problems.
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February 28, 2024 – Lin Chen (this opens in a new tab) and Xuefeng Wen (this opens in a new tab) (Sun Yat-sen University, China) –
On the transitivity of Logical Consequence without Assuming Monotonicity (this opens in a new tab)
Chair: Caroline Pires Ting (this opens in a new tab), International Relations of LUA (this opens in a new tab)
Associate Organization: Institute of Logic and Cognition (this opens in a new tab) presented by its director Hu Liu (this opens in a new tab)
We generalize Ripley’s results on the transitivity of consequence relation, without assuming a logic to be monotonic. Following Gabbay, we assume nonmonotonic consequence relation to be inclusive and cautious monotonic, and figure out the implications between different forms of transitivity of logical consequence. Weaker frameworks without inclusiveness or cautious monotonicity are also discussed. The paper may provide basis for the study of both non-transitive logics and nonmonotonic ones.
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March 13, 2024 – Andrew Schumann (this opens in a new tab) (University of Information Technology and Management in Rzeszow, Poland) –
Stoic Sign-Inference and Their Lore of Fate (this opens in a new tab)
Chair: Srećko Kovač (this opens in a new tab), Editorial Board LU
Associate Organization: Department of Cognitive Science and Mathematical Modelling (this opens in a new tab), University of Information Technology and Management, presented by Jerzy Król (this opens in a new tab)
The Stoics are traditionally regarded as the founders of propositional logic. However, this is not entirely correct. They developed a theory of inference from signs (omens). And their theory became a continuation of the logical technique of Babylonian divination (in particular, of Babylonian medical forecasting). The Stoic theory was not so much propositional logic as it was a technique of propositional logic for databases consisting of IF-THEN expert rules. In the Babylonian divination, each event has a positive or negative value and all events are connected to each other. The Stoics also developed this idea and proposed a special modal logic in which logical determinism is considered an axiom. The paper reconstructs the sign-inference of the Stoics, as well as their modal logic. In particular, two Stoic squares of oppositions are proposed (for signs and for modal operators), which differ markedly from Aristotle's square.
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March 27, 2024 – José M. Sagüillo (this opens in a new tab) (University of Santiago de Compostela, Spain) –
The philosophy of logic of John Corcoran (this opens in a new tab)
Chair: Francesco Paoli (this opens in a new tab), Editorial Board SUL
Book presentation: Universal Logic, Ethics, and Truth (this opens in a new tab)Essays in Honor of John Corcoran (1937-2021) (this opens in a new tab), presented by the editors Timothy Madigan (this opens in a new tab) and Jean-Yves Beziau (this opens in a new tab)
This talk surveys the philosophy of logic of John Corcoran by focusing on some of its characteristic themes: his understanding of logic as formal epistemology articulating the ontic-epistemic distinction of classical metaphysics, the Socratic belief-knowledge distinction, and the Aristotelian truth-knowledge distinction; his conception of mathematical logic as instrumental when considering mathematical logics as models of underlying reasoning found in the practice of proof; his tireless search for a careful and successful communication in a community of thinkers eliminating ambiguity of key terms and embracing ethical values; his discussion of argumentations and logic as a philosophical realization of the previous dichotomies, allowing precise definitions of key concepts, such as, argument, argumentation, proof, deduction, fallacy, and paradox; finally, his recovering and articulation of the XIX century information-theoretic conception of validity, exploring its heuristic power in the study of omega arguments and suggesting the existence of different paradigms of logical consequence equally entrenched in the theory and practice of logic.
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April 10, 2024 – Henri Prade (this opens in a new tab) (Toulouse Institute of Computer Science Research, France), Didier Dubois (this opens in a new tab) (Université Toulouse III - Paul Sabatier, France), Agnès Rico (Claude Bernard University Lyon 1, France) –
Modern vs. classical structures of opposition: A discussion (this opens in a new tab)
Chair: Sayantan Roy, Assistant Editor LU
Associate Organization: ADRIA-IRIT, CNRS (this opens in a new tab) presented by Didier Dubois (this opens in a new tab)
The aim of this work is to revisit the proposal made by Dag Westerståhl a decade ago when he provided a modern reading of the traditional square of opposition and of related structures. We propose a formalization of this modern view and contrast it with the classical one.We discuss what may be a modern hexagon of opposition and a modern cube, and show their interest in particular for relating quantitative expressions.
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April 24, 2024 – Ori Milstein (this opens in a new tab) –
Why the hexagon of opposition is really a triangle: logical structures as geometric shapes
Chair: Arnon Avron, Editorial Board LU
Associate Event: World Congress on the Square of Opposition (this opens in a new tab) presented by Pablo Villalobos Morera and Lorenzo Boccafogli
This paper suggests a new approach (with old roots) to the study of the connection between logic and geometry. Traditionally, most logic diagrams associate only vertices of shapes with propositions. The new approach, which can be dubbed ’full logical geometry’, aims to associate every element of a shape (edges, faces, etc.) with a proposition. The roots of this approach can be found in the works of Carroll, Jacoby, and more recently, Dubois and Prade. However, its potential has not been duly appreciated, probably because of the complexity of the diagrams in these works. The following study demonstrates how the Hexagon of Opposition can be represented as a triangle and Classical Logic as a tetrahedron (rather than a rhombic dodecahedron). It then applies the approach to modal logic, extending the tetrahedron for the logic KT into a dipyramid and a cube for KD, and finally an octahedron for K. Some possible directions for further research are also indicated.
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May 15, 2024 – Takaharu Oda (this opens in a new tab) (Southern University of Science and Technology, China) –
The Buddhist Sengzhao’s Roots in Daoism: Ex Contradictione Nihil
Chair: Caroline Pires Ting (this opens in a new tab), International Relations LUA
Associate Organization: Asian Pragmatism Network presented by Jason Van Boom
Sengzhao (c.374–414) was a Chinese Neo-Daoist who converted to Mah¯ay¯ana Buddhism, and few people doubt his influence on Chinese Buddhist philosophy. In this article, provided his Neo-Daoism (xuanxue) and Madhyamaka Buddhism, I will present how Sengzhao featured a symbolic meaning of ‘void’ (´s¯unya) as rooted originally in Daoism. The Daoist contradictions, in particular between ‘being’ (you) and ‘nothing [non-being]’ (wu), are essential to the development of his doctrine of ‘no ultimate void’ (不真空論, Buzhenkonglun). To understand what Sengzhao meant by ‘void’, which is in denial about the ultimate reality, I broach a notion of nihil (‘nothing’ but also ‘no value’) that bears on his discursive practice. In this light, I formulate a Daoist argument for contradictions and ECN (ex contradictione nihil – nothing follows from contradictions) from Laozi’s Daodejing. Furthermore, I elaborate on Sengzhao’s defence of ECN in his Buzhenkonglun. Reconstructing his negative approach to contradictions within the scope of the four-valued expressions (catus.kot.i) in the Madhyamaka tradition from N¯ag¯arjuna, I consider a likely objection that a fifth value such as the ineffable may be inferred as void. Instead of subsuming the ineffable value under his discourse, I finally endorse Sengzhao’s purpose of linguistic and conventional approximation of the ultimate reality as silence. As such, I conclude the significance of void in Sengzhao’s denials via contradictions (ECN), i.e. an early philosophical peak of Chinese Buddhism from Daoism.
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