Excerpt from Die Prinzipien der Mechanik in Neuem Zusammenhange Dargestellt Wahl eines Berufs entschliefsen mufste, wahlte er den des Ingenieurs. Es scheint, dafs die auch in spateren Jahren als ein charakteristischer Grundzug seines Wesens hervor tretende Bescheidenheit ihn an seiner Begabung fur theore tische Wissenschaft zweifeln liefs, und dafs er sich bei der Beschaftigung mit seinen geliebten mechanischen Arbeiten des Erfolges sicherer fuhlte, weil er deren Tragweite schon damals ausreichend verstand. Vielleicht hat ihn auch die in seiner Vaterstadt herrschende, mehr (...) dem Praktischen zugeneigte Sinnesweise beeinflufst. Ubrigens beobachtet man nicht selten diese Art zaghafter Bescheidenheit gerade bei jungen Leuten von hervorragenden Anlagen. Sie haben wohl eine deutliche Vorstellung von den Schwierigkeiten, die vor der Erreichung des ihnen vorschwebenden hohen Zieles zu uberwinden sind, und mussen ihre Krafte erst praktisch erprobt haben, ehe sie das zu ihrem schweren Werke notige Selbstvertrauen ge winnen. Aber auch in ihrer spateren Entwickelung pflegen reich veranlagte Naturen um so unzufriedener mit ihren eigenen Werken zu sein je hoher ihre Fahigkeiten und ihre Ideale reichen. Die Begabtesten erreichen offenbar nur des halb das Hochste, weil sie am empfindlichsten gegen jede Un vollkommenheit sind, und am unermudlichsten an deren Beseitigung arbeiten. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works. (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)

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)

Personennamen und Religion im alten Israel untersucht mit besonderer Berücksichtigung der Namen auf El und Baʿal. By Stig Norin. Coniectanea Biblica. Old Testament series, vol. 60. Winona Lake, Ind.: Eisenbrauns, 2013. Pp. xiv +336, illus. $49.50.

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)

Many logical systems are such that the addition of Prior's binary connective tonk to them leads to triviality, see [1, 8]. Since tonk is given by some introduction and elimination rules in natural deduction or sequent rules in Gentzen's sequent calculus, the unwanted effects of adding tonk show that some kind of restriction has to be imposed on the acceptable operational inferences rules, in particular if these rules are regarded as definitions of the operations concerned. In this paper, a number (...) of simple observations is made showing that the unwanted phenomenon exemplified by tonk in some logics also occurs in contexts in which tonk is acceptable. In fact, in any non-trivial context, the acceptance of arbitrary introduction rules for logical operations permits operations leading to triviality. Connectives that in all non-trivial contexts lead to triviality will be called non-trivially trivializing connectives. (shrink)

A fundamental notion in a large part of mathematics is the notion of equicardinality. The language with Hartig quantifier is, roughly speaking, a first-order language in which the notion of equicardinality is expressible. Thus this language, denoted by LI, is in some sense very natural and has in consequence special interest. Properties of LI are studied in many papers. In [BF, Chapter VI] there is a short survey of some known results about LI. We feel that a more extensive exposition (...) of these results is needed. The aim of this paper is to give an overview of the present knowledge about the language LI and list a selection of open problems concerning it. After the Introduction $(\S1)$ , in $\S\S2$ and 3 we give the fundamental results about LI. In $\S4$ the known model-theoretic properties are discussed. The next section is devoted to properties of mathematical theories in LI. In $\S6$ the spectra of sentences of LI are discussed, and $\S7$ is devoted to properties of LI which depend on set-theoretic assumptions. The paper finishes with a list of open problem and an extensive bibliography. The bibliography contains not only papers we refer to but also all papers known to us containing results about the language with Hartig quantifier. Contents. $\S1$ . Introduction. $\S2$ . Preliminaries. $\S3$ . Basic results. $\S4$ . Model-theoretic properties of $LI. \S5$ . Decidability of theories with $I. \S6$ . Spectra of LI- sentences. $\S7$ . Independence results. $\S8$ . What is not yet known about LI. Bibliography. (shrink)

First published in 1938. The aim of this book is to expound Kant’s _Critique of Judgement _by interpreting all the details in the light of what Kant himself declares to be his fundamental problem. _A Commentary on Kant’s Critique of Judgement _provides an excellent introduction to Kant’s third critique, and will be of interest to students of philosophy.

In this paper we discuss Gabbay's idea of basing nonmonotonic deduction on semantic consequence in intuitionistic logic extended by a consistency operator and Turner's suggestion of replacing the intuitionistic base system by Kleene's three-valued logic. It is shown that a certain counterintuitive feature of these approaches can be avoided by using Nelson's constructive logic N instead of intuitionistic logic or Kleene's system. Moreover, in N a more general notion of consistency can be defined and nonmonotonic deduction can thus be based (...) on a logical system satisfying the Deduction Theorem. (shrink)

Text: Reproduktion nach Scan der Ausgabe von 1934, Verlag von J. C. B. Mohr (Paul Siebeck) in Tübingen. - Von dem kleinen Buch, das ich hier der Öffentlichkeit übergebe, bitte ich den Leser, nichts anderes zu erwarten, als das, was sein Titel ausdrücklich sagt. Es handelt sich in ihm nicht etwa um die Grundlinien eines Systems der Philosophie, sondern ausschließlich um dessen Probleme, und wenn diese sich auch nicht darlegen lassen, ohne die Richtung anzudeuten, in der das System bei der (...) Ausführung sich zu bewegen hätte, so sollen doch in dieser Schrift hauptsächlich Fragen gestellt, nicht Antworten gegeben werden. Oft brechen die Darlegungen dort ab, wo mancher Leser glauben kann, daß die größten Schwierigkeiten noch ungelöst sind. Ja mehr: nur die Grundprobleme der Philosophie werden erörtert, und das Eingehen auf Sonderfragen ist fast überall vermieden. Einzelheiten sind dann allein herangezogen worden, wenn es zur Verdeutlichung der Hauptbegriffe wünschenswert erschien. [Auszug aus dem Vorwort des Buches]. (shrink)

In this paper it is suggested to generalize our understanding of general (structural) proof theory and to consider it as a general theory of two kinds of derivations, namely proofs and dual proofs. The proposal is substantiated by (i) considerations on assertion, denial, and bi-lateralism, (ii) remarks on compositionality in proof-theoretic semantics, and (iii) comments on falsification and co-implication. The main formal result of the paper is a normal form theorem for the natural deduction proof system N2Int of the bi-intuitionistic (...) logic 2Int. The proof makes use of the faithful embedding of 2Int into intuitionistic logic with respect to validity and shows that conversions of dual proofs can be sidestepped. (shrink)

A theory of substructural negations as impossibility and as unnecessity based on bi-intuitionistic logic, also known as Heyting-Brouwer logic, has been developed by Takuro Onishi. He notes two problems for that theory and offers the identification of the two negations as a solution to both problems. The first problem is the lack of a structural rule corresponding with double negation elimination for negation as impossibility, DNE, and the second problem is a lack of correspondence between certain sequents and a characterizing (...) frame property. While the identification of negation as impossibility and negation as unnecessity does solve Onishi’s problems, in general it nevertheless seems desirable to keep the two notions separate. The present paper addresses the first problem by introducing a reformulation of Onishi’s display sequent calculus in a language of sequents that incorporates Boolean negation. Instead of identifying negation as impossibility and negation as unnecessity, a notion of weak frame correspondence is defined. It is observed that DNE weakly corresponds with a certain frame property, and two structural sequent rules are presented that together also weakly correspond with that frame property and allow one to derive DNE. Moreover, the reformulated display calculus has an independent motivation by considerations on proof-theoretic semantics. (shrink)

En el artículo se hace la presentación de las ideas que san Agustín destaca sobre la Virgen María en sus sermones de Navidad. Se hace en primer lugar una presentación de dichos sermones, para posteriormente abordar el tema de los dos nacimientos de Cristo, que es usado para explicar las dos naturalezas en Cristo (divina y humana). Se destacan asimismo los sermones navideños en los que san Agustín señala el paralelismo entre la Virgen María y la Iglesia, ya ambas son (...) vírgenes y madres. Como un tema central de los sermones de Navidad de san Agustín, el artículo destaca la virginidad perpetua de María. Finalmente se ofrecen unas conclusiones en las que se pone de manifiesto que los sermones de Navidad de san Agustín que tratan sobre la Virgen María son parte de su “teología predicada”. Así como sus grandes tratados desarrollan la Mariología, sus sermones son la popularización de dicho pensamiento mariano. (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)

We consider a labelled tableau presentation of constant domain first-order S5 and prove a strong cut-elimination theorem.