Imagination has recently attracted considerable attention from epistemologists and is recognized as a source of belief and even knowledge. One remarkable feature of imagination is that it is often and typically agentive: agents decide to imagine. In cases in which imagination results in a belief, the agentiveness of imagination may be taken to give rise to indirect doxastic control and epistemic responsibility. This observation calls for a proper understanding of agentive imagination. In particular, it calls for the development of a (...) semantics of imagination ascriptions. In the present paper an earlier suggestion by Ilkka Niiniluoto for a logic of imagination is considered. This proposal does not capture the agentive nature of imagination, and an alternative semantics is suggested. The new semantics combines the modal logic of agency with the neighbourhood semantics from alethic modal logic. (shrink)

It is widely accepted that there is a clear sense in which the first-order paraconsistent constructive logic with strong negation of Almukdad and Nelson, QN4, is more constructive than intuitionistic first-order logic, QInt. While QInt and QN4 both possess the disjunction property and the existence property as characteristics of constructiveness (or constructivity), QInt lacks certain features of constructiveness enjoyed by QN4, namely the constructible falsity property and the dual of the existence property. This paper deals with the constructiveness of the (...) contra-classical, connexive, paraconsistent, and contradictory non-trivial first-order logic QC, which is a connexive variant of QN4. It is shown that there is a sense in which QC is even more constructive than QN4. The argument focuses on a problem that is mirror-inverted to Raymond Smullyan’s drinker paradox, namely the invalidity of what will be called the drinker truism and its dual in QN4 (and QInt), and on a version of the Brouwer-Heyting-Kolmogorov interpretation of the logical operations that treats proofs and disproofs on a par. The validity of the drinker truism and its dual together with the greater constructiveness of QC in comparison to QN4 may serve as further motivation for the study of connexive logics and suggests that constructive logic is connexive and contradictory (the latter understood as being negation inconsistent). (shrink)

Over the past ten years, the community researching connexive logics is rapidly growing and a number of papers have been published. However, when it comes to the terminology used in connexive logic, it seems to be not without problems. In this introduction, we aim at making a contribution towards both unifying and reducing the terminology. We hope that this can help making it easier to survey and access the field from outside the community of connexive logicians. Along the way, we (...) will make clear the context to which the papers in this special issue on Frontiers of Connexive Logic belong and contribute. (shrink)

In a recent article, Mario Günther presented a conditional that is claimed to be connexive. The aim of this short discussion note is to show that Günther’s claim is not without problems.

El presente artículo examina los discursos histórico-geográficos sobre América transmitidos en China por misioneros jesuitas entre los siglos XVI y XVIII. Este busca demostrar el modo en que misioneros y sus colaboradores chinos crearon, cuidadosa y estratégicamente, sus informaciones sobre el continente con el fin de apoyar su agenda política y misional. El texto comienza con una descripción general de las estrategias de la misión en China y su relación con la producción geográfica sino-jesuita, para luego ejemplificar a través de (...) un análisis de los contenidos sobre la geografía, etnografía y el “descubrimiento” del continente, la conexión de estas informaciones con los planes de la misión. El artículo concluye que las representaciones sobre la geografía, gentes e historia de América reflejan tres intereses interrelacionados: atraer la atención de los literatos chinos; resaltar el alto desarrollo de la civilización europea; y comunicar mensajes religiosos. (shrink)

The knowability paradox is an instance of a remarkable reasoning pattern (actually, a pair of such patterns), in the course of which an occurrence of the possibility operator, the diamond, disappears. In the present paper, it is pointed out how the unwanted disappearance of the diamond may be escaped. The emphasis is not laid on a discussion of the contentious premise of the knowability paradox, namely that all truths are possibly known, but on how from this assumption the conclusion is (...) derived that all truths are, in fact, known. Nevertheless, the solution offered is in the spirit of the constructivist attitude usually maintained by defenders of the anti-realist premise. In order to avoid the paradoxical reasoning, a paraconsistent constructive relevant modal epistemic logic with strong negation is defined semantically. The system is axiomatized and shown to be complete. (shrink)

The topic of identity of proofs was put on the agenda of general (or structural) proof theory at an early stage. The relevant question is: When are the differences between two distinct proofs (understood as linguistic entities, proof figures) of one and the same formula so inessential that it is justified to identify the two proofs? The paper addresses another question: When are the differences between two distinct formulas so inessential that these formulas admit of identical proofs? The question appears (...) to be especially natural if the idea of working with more than one kind of derivations is taken seriously. If a distinction is drawn between proofs and disproofs (or refutations) as primitive entities, it is quite conceivable that a proof of one formula amounts to a disproof of another formula, and vice versa. A notion of inherited identity of derivations is introduced for derivations in a cut-free sequent system for Almukdad and Nelson’s constructive paraconsistent logic N4 with strong negation. The notion is obtained by identifying sequent rules the application of which has no effect on the identity of derivations. Then the notion of inherited identity is used to define a bilateralist notion of synonymy between formulas, which is a relation drawing more fine-grained distinctions between formulas than strong equivalence. (shrink)

In this paper, first some propositional conditional logics based on Belnap and Dunn’s useful four-valued logic of first-degree entailment are introduced semantically, which are then turned into systems of weakly and unrestrictedly connexive conditional logic. The general frame semantics for these logics makes use of a set of allowable (or admissible) extension/antiextension pairs. Next, sound and complete tableau calculi for these logics are presented. Moreover, an expansion of the basic conditional connexive logics by a constructive implication is considered, which gives (...) an opportunity to discuss recent related work, motivated by the combination of indicative and counterfactual conditionals. Tableau calculi for the basic constructive connexive conditional logics are defined and shown to be sound and complete with respect to their semantics. This semantics has to ensure a persistence property with respect to the preorder that is used to interpret the constructive implication. (shrink)

Curry’s paradox is well known. The original version employed a conditional connective, and is not forthcoming if the conditional does not satisfy contraction. A newer version uses a validity predicate, instead of a conditional, and is not forthcoming if validity does not satisfy structural contraction. But there is a variation of the paradox which uses “external validity”. And since external validity contracts, one might expect the appropriate version of the Curry paradox to be inescapable. In this paper we show that (...) this is not the case. We consider two ways of formalising the notion of external validity, and show that in both of these the paradox is not forthcoming without the appropriate forms of contraction. (shrink)

Proof Theory of Modal Logic is devoted to a thorough study of proof systems for modal logics, that is, logics of necessity, possibility, knowledge, belief, time, computations etc. It contains many new technical results and presentations of novel proof procedures. The volume is of immense importance for the interdisciplinary fields of logic, knowledge representation, and automated deduction.

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)

This conflict can be interpreted in both religious and nonreligious ways. However, some intellectuals have identified a common thread parallel to the theological axis. The research study determines the role of existential philosophy in the contemporary religious beliefs. They have interpreted this contradiction as the conflict between our current selves and aspirations. Recognizing our animality and the role that such creatures play in the world is a requirement of our rational side. You may guarantee a well-attended eulogy by eating well, (...) exercising, not being a burden, helping out where you can, raising the next generation, and leaving the area essentially as you found it when it's time to leave. We must deal with this since it is who we are and what we are at our core. However, to be human means to be unhappy with this chilly, conventional assessment. As human beings, we possess the capacity to make decisions that influence our potential. Our destiny is not predetermined and that we can use our willpower to slightly warm the universe's unbreakable laws so that we can bend and shape them into the things we want. In the end, the cosmos prevails, yet we try to become rather than just exist during our brief existence. In the ongoing struggle against finitude, we strive for transcendence. The general framework has secular and strong religious proponents, and this view has been widely referred to as existentialist. (shrink)

References to God. Some Remarks by Wittgenstein on Religion in the Years 1949 – 51. After a brief overview of Wittgenstein's stock of remarks on the subject of religion from 1949 – 1951, this article will focus on two particular points: (1) supposedly nonsensical conceptions of God, for instance in the context of proofs of God, (2) definitions of the term ”God” by hinting at something. Connections between (1) and (2) both systematically and exegetically within the framework of Wittgenstein's remarks (...) are made. Ich danke Anja Weiberg für sehr hilfreiche Kommentare. (shrink)

Ein Buch nicht der Re-Mythisierung, sondern der Mythoskritik, allerdings einer Kritik, die den Mythos ernst nimmt. Daher: »Mein Thema lautet: die Funktion der Genealogie im Mythos. So formuliert, setzt es eine rationale Vorstellung vom Funktionieren des Mythos voraus – es fordert zu einer systematischen Erörtertung auf. Wir brauchen nicht zu befürchten, daß eine systematische Erörterung das Mystische des Mythos verfehlt, weil sie archaische Verhältnisse dem Zwang der Rationalität unterwirft. Eher wird sie die Verbindung deutlich machen, die zwischen Mythos, Rationalität und (...) Zwang besteht.«. (shrink)

Bei Gilles Deleuze findet man einen der seltenen Ansätze zu einem genuin philosophischen Verständnis der Linie. Er versucht eine Emanzipation der Linie nicht nur aus der Geometrie, sondern auch aus der Dominanz des Raumes. Die wichtigsten Motive, die ihn dabei leiten, hat er in dem Konzept der Fluchtlinie gebündelt. Dessen potentiell metaphorischer Status wird ebenso befragt wie seine Aussagekraft für das deleuzianische Verständnis von Philosophie überhaupt. The work of Gilles Deleuze is one of the rare cases in which a genuinely (...) philosophical understanding of the line is attempted. He not only tries to dissociate the line from geometry, but also to free it from the dominance of space. The most important motives behind his thinking about the line converge in the concept of the ›ligne de fuite‹. The text examines the potentially metaphorical status of this notion, as well as its significance for Deleuze’s view of philosophy in general. (shrink)

Dieser Buchtitel ist Teil des Digitalisierungsprojekts Springer Book Archives mit Publikationen, die seit den Anfängen des Verlags von 1842 erschienen sind. Der Verlag stellt mit diesem Archiv Quellen für die historische wie auch die disziplingeschichtliche Forschung zur Verfügung, die jeweils im historischen Kontext betrachtet werden müssen. Dieser Titel erschien in der Zeit vor 1945 und wird daher in seiner zeittypischen politisch-ideologischen Ausrichtung vom Verlag nicht beworben.