This paper discusses the development of the Logic and Religion project and the various events organized within this framework, particularly the 3rd and 4th editions, with this volume including papers presented at both.

Sengzhao (c.374–414) was a Chinese Neo-Daoist who converted to Mahāyāna 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’ (śūnya) 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 (catuṣkoṭi) in the Madhyamaka tradition from Nāgārjuna, 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 to 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. (shrink)

This study investigates the intricate process of visualizing the concept of paradise through the lens of Artificial Intelligence (AI), employing neural networks to craft intricate visual depictions of utopian realms. The project scrutinizes the prevalent themes associated with paradisiacal imagery, dissecting the intricate weave of religious doctrines, mythologies, and the intrinsic nature of paradise – be it a tangible realm or a metaphysical state. This inquiry critically assesses the role of AI-generated art, derived from complex algebraic formulations, in mirroring conventional (...) iconography and exposing inherent biases. Such revelations underscore the cultural resonance of diverse traditions and the potential presence of subconscious prejudices. Employing AI algorithms capable of transforming textual prompts into vivid illustrations, this research unveils insights into the nexus of AI and cultural portrayals of utopia, thereby provoking profound philosophical deliberations. Central to these contemplations is the extent of human dominion over conceptualized ideals and the prospect of AI-crafted art inadvertently molding our paradisiacal perceptions, with implications ranging from reinforcement of stereotypes to shaping intrinsic cognitive schemas. (shrink)

How to reach Paradise using only a few idealized and limited representational fragments gathered over a lifetime? After having specified the logical questions raised by the (re)presentation of a paradisiacal world, we show that such a world, in order to have the characteristics usually attributed to Paradise (such as unity or plenitude), must satisfy specific representational properties with respect to the Good. In order to clarify the impact of these properties on the access to Paradise, we introduce the Grounded Representation (...) Theory which allows the construction of represented universes. Building on this framework, we then propose directions for a logical analysis of the power of experiences that, from limited fragments of presence, enable one to initiate the ascent towards Paradis. (shrink)

In his precritical period Kant developed a demonstration of the existence of God that he believed to be the only possible one. Whether this argument is valid is a much-disputed question. To give an answer to this question I will reconstruct Kant’s argument with the means of modern logic and semantics and show which are—in my view—it’s weak points. To achieve this, I will use a combination of the formalism of predicate-, propositional and modal logic without, thought, introducing such a (...) combined logic. (shrink)

In this paper I present a formalization of the theory of ideal concepts applied to the concept of God. It is done within a version of the Simplest Quantified Modal Logic (SQML) and attempts to solve three meta-problems related to the concept of God: the unicity of extension problem, the homogeneity/heterogeneity problem and the problem of conceptual unity.

In this article, I illustrate the universalism of logic using the example of Stephen Langton’s ($$\dagger $$ † 1228) exegesis presented in his theological question 103. This text refers to the biblical story of Isaac blessing his son Jacob, who pretended to be his brother, Esau. I present the universalism of logic understood as its broad applicability and effectiveness. I argue that logic is very useful even in analyzing biblical exegesis. Langton’s exegesis benefits from logical knowledge on different levels. One (...) of them is the application of a semiotic theory to formulate a solution to the problem of the validity of Isaac’s blessing. Above all, Langton distinguishes between a discrete and a vague (or simple) use of the pronoun “you.” Notably, Langton’s analysis of various speech acts in terms of his semiotic (or pragmatic) theory is also a basis to formulate the conditions of felicity of the act of blessing (understood in the theological context), which shows that logic can be not only broadly applicable, but also effective. Finally, question 103 proves that logic is universal also in a different way, namely: it can provide solutions which are acceptable for representatives of different traditions. (shrink)

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.

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. (shrink)

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. (shrink)

There are two general conceptions on the relationship between probability and logic. In the first, these systems are viewed as complementary—having offsetting strengths and weaknesses—and there exists a fusion of the two that creates a reasoning system that improves upon each. In the second, probability is viewed as an instance of logic, given some sufficiently broad formulation of it, and it is this that should inform the development of more general reasoning systems. These two conceptions are in conflict with each (...) other, where the root issue of contention is the proper abstraction of the concept of logical consequence. In this work, we put forth a proposal on this abstraction based on an extension of the subset relation through the use of projections, which in turn, allows for the formalization of valid inferences to more general settings. Our proposal results in a formalism that encompasses probability and classical logic, and importantly, does so with minimal machinery. This formalism makes assertions about the relationship between these two systems that are explicit, and suggests a path forward in the development of alternatives to them. (shrink)

Cut-elimination theorems constitute one of the most important classes of theorems of proof theory. Since Gentzen’s proof of the cut-elimination theorem for the system LK, several other proofs have been proposed. Even though the techniques of these proofs can be modified to sequent systems other than $$\textbf{LK}$$, they are essentially of a very particular nature; each of them describes an algorithm to transform a given proof to a cut-free proof. However, due to its reliance on heavy syntactic arguments and case (...) distinctions, such an algorithm makes the fundamental structure of the argument rather opaque. We, therefore, consider rules abstractly, within the framework of logical structures familiar from universal logic in the sense of Béziau (Universal logic, Prague, 1994) and aim to clarify the essence of the so-called “elimination theorems”. To do this, we first give a non-algorithmic proof of the cut-elimination theorem for the propositional fragment of $$\textbf{LK}$$. From this proof, we abstract the essential features of the argument and define something called normal sequent structures relative to a particular rule. We then prove a version of the rule-elimination theorem for these. Abstracting even more, we define abstract sequent structures and show that for these structures, the corresponding version of the rule-elimination theorem has a converse as well. (shrink)

We describe how finite colimits can be described using the internal lanuage, also known as the Mitchell-Benabou language, of a topos, provided the topos admits countably infinite colimits. This description is based on the set theoretic definitions of colimits and coequalisers, however the translation is not direct due to the differences between set theory and the internal language, these differences are described as internal versus external. Solutions to the hurdles which thus arise are given.

We discuss the history of the revival of the theory of opposition, with its emerging paradigms of research, and the related events that are organized in this perspective, including the latest one in Leuven in 2022.

The aim of this paper is to analyse categorical propositions and their oppositional relations in Avicenna’s frame. For Avicenna’s expression and conception of categorical propositions is different from those of the authors who preceded him, due to the various conditions he adds to these categorical propositions. These additions make the oppositional relations richer and give rise to many more figures than a simple square. Our analysis exhibits some of these figures by relating all kinds of quantified propositions in various ways. (...) We thus find many squares of oppositions, several octagons, two hexagons and many complex figures which are different from each other and have specific and original structures, due to the propositions they contain. The hexagons are of Blanché’s kind, but one of them is asymmetric. Some octagons are of Buridan’s kind, but one of them is very unusual and seems to be a reversal of Buridan’s octagon. These octagons can also be replaced by cubes, which are three dimensional figures having the same number of vertices. (shrink)

In this paper is constructed an analogue of the square of opposition for propositions about relations between two non-empty sets. Unlike the classical square of opposition, the proposed scheme uses all logically possible syllogistic constants, formulated in V.I. Markin’s universal language for traditional positive syllogistic theories. This scheme can be called “Logical lantern”. The basic constants of this language are representing the five basic relations between two non-empty sets: equity, strict inclusion, reversed strict inclusion, intersection and exclusion (considered are only (...) the relations between sets, but not the relations of the sets to the universe). The other relations between sets are combinations (disjunctions) of the basic ones. There are 32 constants and 32 respective propositions, and the proposed diagram expresses and/or allows to deduce the logical relations among those propositions. The constructed scheme, making it possible to visually see the logical relations among propositions about relations between two non-empty sets, allows us to suggest considering logical relations not discussed previously: many-place Aristotelian-like logical relations among propositions: exhaustive _n_-place contrariety and exhaustive _n_-place subcontrariety (_n_ is a natural number, \(n>2\) ). (shrink)

In logical geometry, Aristotelian diagrams are studied in a precise and systematic way. Although there has recently been a good amount of progress in logical geometry, it is still unknown which underlying mathematical framework is best suited for formalizing the study of these diagrams. Hence, in this paper, the main aim is to formulate such a framework, using the powerful language of category theory. We build multiple categories, which all have Aristotelian diagrams as their objects, while having different kinds of (...) morphisms between these diagrams. The categories developed here are assessed according to their ability to generalize previous work from logical geometry as well as their interesting category-theoretical properties. According to these evaluations, the most promising category has as its morphisms those functions on fragments that increase in informativity on both the opposition and implication relations. Focusing on this category can significantly increase the effectiveness of further research in logical geometry. (shrink)

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.

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. (shrink)

In this publication we continue the study of fuzzy Peterson’s syllogisms. While in the previous publication we focused on verifying the validity of these syllogisms using the construction of formal proofs and semantic verification, in this publication we focus on verifying the validity of syllogisms using Peterson’s rules based on grades.

The objects called cubes of opposition have been presented in the literature in discordant ways. The aim of the paper is to offer a survey of such various kinds of cubes and evaluate their relation with an object, here called “Aristotelian cube”, which consists of two Aristotelian squares and four squares which are semiaristotelian, i.e. are such that their vertices are linked by some so-called Aristotelian relation. Two paradigm cases of Aristotelian squares are provided by propositions written in the language (...) of the logic of consequential implication, whose distinctive feature is the validity of two formulas, A $$\rightarrow $$ → B $$\supset \lnot $$ ⊃ ¬ (A $$\rightarrow $$ → $$\lnot $$ ¬ B) and A $$\rightarrow $$ → B $$\supset \lnot $$ ⊃ ¬ ($$\lnot $$ ¬ A $$\rightarrow $$ → B), expressing two different forms of contrariety. Part of section 1 is devoted to define the notions of rotation and of r-Aristotelian square, i.e. a square resulting from some rotation of an Aristotelian square. In section 2 this notion is extended to the one of a r-Aristotelian cube, i.e. of a cube resulting from some rotation of some square of an Aristotelian cube. This notion is used in the sequel to analyze various cubes of oppositions which can be found in the literature: (1) the one used by W. Lenzen to reconstruct Caramuel’s Octagon; (2) the one used by D. Luzeaux to represent the implicative relation among S5-modalities; (3) the one introduced by D. Dubois to represent the relations between quantified propositions containing positive predicates and their negations; (4) the one called Moretti cube. None of such cubes is strictly speaking Aristotelian but each of them may be proved to be r-Aristotelian. Section 5 discusses the assertion that Dubois cube was anticipated in a paper published by Reichenbach in 1952. Actually Dubois’ construction was anticipated by the so-called Johnson–Keynes cube, while the Reichenbach cube, unlike Dubois cube, is an instance of an Aristotelian cube in the sense defined in this paper. The dominance of such notion is confirmed by J.F. Nilsson’s cube, representing relations between propositions with nested quantifiers, and also by a cube introduced by S. Read to treat quantifiers with existential import. A cube similar to Read’s cube, introduced by Chatti and Schang, is shown to be r-Aristotelian. In section 6 the author remarks that the logic of the formulas occurring in the cubes of Chatti–Schang and Read have the drawback of not satsfying the law of Identity. He then proposes a definition of non-standard quantifiers which satisfies Identity, are independent of existential assumptions and such that their interrelations are represented by an Aristotelian cube. (shrink)

The present paper wants to develop a formal semantics about a special class of formulas: quantifying statements, which are a kind of predicative statements where both subject- and predicate terms are quantifier expressions like ‘everything’, ‘something’, and ‘nothing’. After showing how talking about nothingness makes sense despite philosophical objections, I contend that there are two sorts of meaning in phrases including ‘thing’, viz. as an individual (e.g. ‘some thing’) or as a property (e.g. ‘something’). Then I display two kinds of (...) logical forms for quantifying statements, depending on how these ‘thing’s are ordered into a whole predication. Finally, an algebraic semantics is proposed for the finite set of quantifying statements to order these into a (fragmentary) dodecagon of logical relations. The corresponding Sub-Model Semantics (hereafter: $$\mathbb {SMS}$$ ) aims to update the usual theory of opposition whilst leading to a research program for other kinds of statement like categorical and even modal propositions. (shrink)

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. (shrink)

This paper investigates some classical oppositional categories, like synthetic versus analytic, posterior versus prior, imagination versus grammar, metaphor versus hermeneutics, metaphysics versus observation, innovation versus routine, and image versus sound, and the role they play in epistemology and philosophy of science. The epistemological framework of _objective cognitive constructivism_ is of special interest in these investigations. Oppositional relations are formally represented using algebraic lattice structures like the cube and the hexagon of opposition, with applications in the contexts of modern color theory, (...) Kantian philosophy, Jungian psychology, and linguistics. (shrink)