Logical reflection in early modern philosophy (EMP) is marked by the instability of the period, although it is more lasting (the Port-Royal Logic was nevertheless used as a handbook in philosophy courses until the end of the nineteenth century). It started in the sixteenth century and ended in the nineteenth century, a period of 300 years during which there were deep transformations in the conceptions of authority and scientific method. For the history of twentieth-century philosophy, it was the period of (...) “classical logic,” which lasted from the Renaissance to the linguistic turn conducted by Gottlob Frege. The period was used to be thought of as centuries of little or no original contribution to logic, in which conceptions of logic were tainted by rhetoric, epistemology, and psychologism in the worst sense (Kneale and Kneale 1962; Michael 1997). From the last decades of the twentieth century, however, scholars began to regard this period more accurately with respect to reflection and changes in logic and semantics. It has recently become a promising field for historical and conceptual research; today we can say that the legacy of early modern logical reformism has a philosophical, logical, and semantic value in itself. (shrink)

Logic, an old discipline with a long history, is a product of the nature of thinking that is based on mental thought, which is distinguished from other creatures by human nature. Logical thought and various forms of rational inference, seen in all the geographical regions of the world before attaining a systematic structure, have directed to human life and its scientific products. A systematic structure is taken back to Parmenides, lived in ancient Greek thought. The logic developed from various directions (...) was given a proper shape by Aristotle nearly two thousand years ago and has been in continuous development and transformation in the direction of human mind and its needs. Today, in addition to Aristotelian logic, which is two most valuable structures, many valued logics have emerged.. Quite different logic conception emerges from classical logic, however, which is considered as a beginning for philosophical thought and is one of the important factors in reaching the goal of the philosophical effort. But the presence of classical logic continues in the areas of religious, classical philosophy and social sciences. In this frame, the value of classical logic from past histories requires the position that it deserves. Especially, in the area of logic as well as the problems faced in logic education, more effective planning is required especially in the higher education level. This article will briefly discuss the structure of logic and its various interpretations. It will also point out the importance of logic and will draw attention to the problems in the Theology Faculties. A few suggestions that we want to discuss in this framework will also be put forward. (shrink)

En este artículo recuperamos la lógica diagramática lineal de Leibniz para la silogística y descubrimos sus propiedades lógicas y computacionales a través de una aproximación formal en términos metalógicos, lo cual es algo que, hasta donde sabemos, aún falta por hacerse. Así, en esta contribución buscamos, respectivamente, dos metas, una histórica y una lógica: i) prestar más atención a los aspectos algorítmicos del sistema diagramático lineal de Leibniz para la silogística, de los cuales creemos que han sido desdeñados por un (...) prejuicio general en contra del razonamiento diagramático; y ii) probar propiedades metalógicas del sistema para argumentar que es un sistema lógico bona fide. (shrink)

ABSTRACTHere, I pursue consequences, for the interpretation of Sellars’ critique of the ‘Myth of the Given’, of separating the modal significance that Kant attributed to empirical intuition from th...

Fetzer famously claims that program verification is not even a theoretical possibility, and offers a certain argument for this far-reaching claim. Unfortunately for Fetzer, and like-minded thinkers, this position-argument pair, while based on a seminal insight that program verification, despite its Platonic proof-theoretic airs, is plagued by the inevitable unreliability of messy, real-world causation, is demonstrably self-refuting. As I soon show, Fetzer is like the person who claims: ‘My sole claim is that every claim expressed by an English sentence and (...) starting with the phrase “My sole claim” is false’. Or, more accurately, such thinkers are like the person who claims that modus tollens is invalid, and supports this claim by giving an argument that itself employs this rule of inference. (shrink)

In the 1930s, C. I. Lewis, who was responsible for the revival of modal logic in the era of modern symbolic logic, characterized ‘intensional’ approaches to logic as typical of post-Leibnizian ‘continental philosophy’, in contrast to the ‘extensionalist’ approaches dominant in the British tradition. Indeed Lewis’s own work in this area had been inspired by the logic of his teacher, the American ‘Absolute Idealist’, Josiah Royce. Hegel’s ‘Subjective Logic’ in Book III of hisScience of Logic, can, I suggest, be considered (...) as an intensional modal logic, and this paper explores parallels between it and a later variety of modal logic—tenselogic, as developed by Arthur Prior in the 1950s and 60s. Like Lewis, Prior too had been influenced in this area by a teacher with strong Hegelian leanings—John N. Findlay. Treated as anintensional(with an ‘s’) logic, Hegel’s subjective logic can be used as a framework for addressing issues ofintentionality(with a ‘t’)—the mind’s capacity to be intentionally directed to objects. In this way, I suggest that the structures of his subjective logic can clarify what is at issue in the ‘Psychology’ section of theEncyclopaediaPhilosophy of Subjective Spirit. (shrink)

To explore the extent of embeddability of Leibnizian infinitesimal calculus in first-order logic (FOL) and modern frameworks, we propose to set aside ontological issues and focus on pro- cedural questions. This would enable an account of Leibnizian procedures in a framework limited to FOL with a small number of additional ingredients such as the relation of infinite proximity. If, as we argue here, first order logic is indeed suitable for developing modern proxies for the inferential moves found in Leibnizian infinitesimal (...) calculus, then modern infinitesimal frameworks are more appropriate to interpreting Leibnizian infinitesimal calculus than modern Weierstrassian ones. (shrink)

Classical higher-order logic, when utilized as a meta-logic in which various other logics can be shallowly embedded, is well suited for realising a universal logic reasoning approach. Universal logic reasoning in turn, as envisioned already by Leibniz, may support the rigorous formalisation and deep logical analysis of rational arguments within machines. A respective universal logic reasoning framework is described and a range of exemplary applications are discussed. In the future, universal logic reasoning in combination with appropriate, controlled forms of rational (...) argumentation may serve as a communication layer between humans and intelligent machines. (shrink)

There are various ways of achieving an enlarged understanding of a concept of interest. One way is by giving its proper definition. Another is by giving something else a proper definition and then using it to model or formally represent the original concept. Between the two we find varying shades of grey. We might open up a concept by a direct lexical definition of the predicate that expresses it, or by a theory whose theorems define it implicitly. At the other (...) end of the spectrum, the modelling-this-as-that option also admits of like variation, ranging from models rooted in formal representability theorems to models conceived of as having only heuristic value. There exist on both sides of this divide further differences still. In one of them, both the definiendum and definiens of a definition are words or phrases of some common natural language. In others, the item of interest is a natural language expression and its representation is furnished by the artificial linguistic system that models it. The modern history of these approaches is both very large and growing. Much of this evolution has given too short a shrift to the history of the demotion of ‘intuitive’ concepts in favour of the artificially contrived ones intended to model them. A working assumption of this article is that in the absence of a good understanding of what motivated the modelling-turn in the foundations of mathematics and the intuitive theory of truth, the whole notion of formal representability will have been inadequately understood. In the interests of space, I will concentrate on seminal issues in set theory as dealt with by Russell and Frege, and in the theory of truth in natural languages as dealt with by Tarski. The nub of the present focus is the representational role of model theory in the logics of formalized languages. (shrink)