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Context is essential in virtually all human activities. Yet some logical notions seem to be context-free. For example, the nature of the universal quantifier, the very meaning of “all”, seems to be independent of the context. At the same time, there are many quantifier expressions, and some are context-independent, while others are not. Similarly, purely logical consequence seems to be context-independent. Yet often we encounter strong inferences, good enough for practical purposes, but not valid. The two types of examples suggest a general problem: how to characterise the context-free logical concepts in their natural environment, that is, in the field of their context-dependent associates. A general Thesis on Quantifiers is formulated: among all quantifiers, the context-free ones are just those definable by the universal quantifier. The issue of inferences is treated following the approach introduced by Richard L. Epstein: valid ones are an extreme case, the result of the disappearance of context-dependence. This idea can be applied to an analysis of a form of abduction, called “reductive inference” in Polish literature on logic. A tentative Thesis on Inferences identifies the validity of a strong inference that is context-independent.

Like most issues within the philosophical realm there are controversies surrounding the nature and subject matter of philosophical logic and philosophy of logic. While some philosophers on the one hand see philosophical logic as using logic as a tool to deal with philosophical problems and take philosophy of logic as a self-check method whereby the tools of logic itself are critically analysed, others on the other hand see no distinction between both. For instance, Susan Haack supports the latter position that there is no clear distinction between both fields while A.C. Grayling and Dale Jacquette are adherents of the former position. This paper attempts an expository analysis of the characteristics of both philosophical logic and philosophy of logic. It argues that though there are basic distinctions in their features, there are points of intersection which makes them co-relevant in the development of logic, philosophy and other related fields. [ABSTRACT FROM AUTHOR]

This article proposes the use of temporal logic for an analysis of instrumentality inspired by the work of G.H. von Wright. The first part of the article contains the philosophical foundations. We discuss von Wright's general theory of agency and his account of instrumentality. Moreover, we propose several refinements to this framework via rigorous definitions of the core notions involved. In the second part, we develop a logical system called Temporal Logic of Action and Expectations (TLAE ). The logic is inspired by a fragment of propositional dynamic logic based on indeterministic time. The system is proven to be weakly complete relative to its given semantics. We then employ TLAE to formalise and analyse the instrumentality relations defined in the first part of the paper. Last, we point out philosophical implications and possible extensions of our work. [ABSTRACT FROM AUTHOR]

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The so-called Principle of Plenitude was ascribed to Leibniz by A.O. Lovejoy in The Great Chain of Being: A Study of the History of an Idea [9]. Its temporal version states that what holds always, holds necessarily (or that no genuine possibility can remain unfulfilled). This temporal formulation is the subject of the current paper. Lovejoy's idea was criticised by Hintikka. The latter supported his criticisms by referring to specific Leibnizian notions of absolute and hypothetical necessities interpreted in a possible-worlds semantics. In the paper, Hintikka's interpretative suggestions are developed and enriched with a temporal component that is present in the characteristics of the real world given by Leibniz. We use in our approach the Leibnizian idea that change is primary to time and the idea that there are possible laws that characterize worlds other than the real one. We formulate a modal propositional logic with three primitive operators for change, temporal constancy, and possible lawlikeness. We give its axiomatics and show that our logic is complete with respect to the given semantics of possible worlds. Finally, we show that the counterparts of the considered versions of the Principle of Plenitude are falsified in this semantics and the same applies to the counterpart of Leibnizian necessarianism. [ABSTRACT FROM AUTHOR]

This paper proves a precisification of Hume's Law—the thesis that one cannot get an ought from an is—as an instance of a more general theorem which establishes several other philosophically interesting, though less controversial, barriers to logical consequence. [ABSTRACT FROM AUTHOR]

We are discussing important problems prior to philosophy of logic that Non-classical logic has raised. The main one is the proliferation and, respectively, the question of monism and pluralism in logic. Another challenge to philosophy, related to the imposition of non-classical logic, is the appearance and application of the term “philosophical logic”. For me, two questions related in fundamental ways. Because I believe that one of the answers to the question, “What, actually, is “philosophical logic’?” is that part of its task is to philosophically discuss precisely the problems that the emergence and validation of non-classical logic pose for philosophy. And this is a concrete example of how to understand the tasks of the still unclear concept of "philosophical logic". So I will first focus on this notion. As for the reasons for the term – “scientific and theoretical”, and “social and practical”, I will mainly focus on the first, but in the end I will also touch on the second. [ABSTRACT FROM AUTHOR]

The paper in the first place aims to clarify the concept of self-referring sentence through a revision of the standard account; in the second place it deals with the meaningfulness of the self-referring sentence 'What I am hereby asserting is true'; in the third place it discusses the advantages and limits of the Rylean namelyrider approach to the problem of self-referring sentences. [ABSTRACT FROM AUTHOR]

The article aims to set and consider the problem of demarcation between both, formal and philosophical logic. It grows like a series of different stories where the point of philosophical logic is mentioned. The failure to demarcate its field is in the basis of many of the difficulties that arise when Russell tries to form his own conception for logical analysis and for observing the logical data. An attempt is proposed to locate and elucidate some transcendental components that could be visible when we are focused on Russell's analytical practice. Although some thoughts are polemical, in my opinion, they have the power to form an impulse for outlining the aria of philosophical logic. [ABSTRACT FROM AUTHOR]

The article discusses some of the main problems of Russell's philosophical logic and the ambiguous solutions he undertook in its field, related primarily to the problem of form. The article puts a more detailed emphasis on Russell's frequently changing views on the nature of propositions, as related to the method of logical analysis applied in Principles of Mathematics (1903), in an unpublished manuscript on Theory of Knowledge (1913), and in Introduction to Mathematical Philosophy (1918). The main questions this article attempts to answer are the following. Why did Russell repeatedly return to issues he had already discussed, rejecting his previous assertions and, if not replacing them with new ones, at least thinking them in a new way? Why did he not give a definite answer to the question as to what propositions are and how they should be analyzed, and does this have some connection with the missing answer to the question of logical forms? [ABSTRACT FROM AUTHOR]

I shall argue in this article that, if we need to admit of negative facts in our ontology as falsemakers of false propositions (as I try to demonstrate in a 2014 article by a falsemaker argument), then it is plausible to accept that there are also negative properties conceived of as modes. After having briefly recalled the falsemaker argument, I shall explore five different alternative interpretations of negative facts and I shall demonstrate that each alternative - except for the one involving negative properties - is affected by some problems. Later on, I shall deal with a number of objections against negative properties and I shall demonstrate that they can be overcome without much difficulty. Eventually, I shall tackle Nick Zangwill's argument against the thesis that negative properties are as real as positive ones. Among other things, I shall argue that Zangwill's argument is at least limited in its scope, since it only works with negative and positive determinates within some common determinable. [ABSTRACT FROM AUTHOR]

Contemporary logic is confined to a few paradigmatic attitudes such as belief, knowledge, desire and intention. My purpose is to present a general model-theoretical semantics of propositional attitudes of any cognitive or volitive mode. In my view, one can recursively define the set of all psychological modes of attitudes. As Descartes anticipated, the two primitive modes are those of belief and desire. Complex modes are obtained by adding to primitive modes special cognitive and volitive ways or special propositional content or preparatory conditions. According to standard logic of attitudes (Hintikka), human agents are either perfectly rational or totally irrational. I will proceed to a finer analysis of propositional attitudes that accounts for our imperfect but minimal rationality. For that purpose I will use a non standard predicative logic according to which propositions with the same truth conditions can have different cognitive values and I will explicate subjective in addition to objective possibilities. Next I will enumerate valid laws of my general logic of propositional attitudes. At the end I will state principles according to which minimally rational agents dynamically revise attitudes of any mode.

We investigate incomplete symbols, i.e. definite descriptions with scope-operators. Russell famously introduced definite descriptions by contextual definitions; in this article definite descriptions are introduced by rules in a specific calculus that is very well suited for proof-theoretic investigations. That is to say, the phrase 'incomplete symbols' is formally interpreted as to the existence of an elimination procedure. The last section offers semantical tools for interpreting the phrase 'no meaning in isolation' in a formal way. [ABSTRACT FROM AUTHOR]

This study presents the contents of 'the science of philosophical logic' and 'the science of linguistic logic' which are found in Eisagoge text in the Ikhwân al-Safâ's Rasâilu Ikhwân al- Safâ. This study also assesses these contents in terms of the history of logic. 'Philosophical logic' is a term, also used in the modern era and also it is possible to talk about the "presentday" a discipline of linguistic logic. It seems to me that these were seen in the tractates of Ikhwan al-Safâ (10th century) for the first time although their usage was somehow different than their contemporary usage. [ABSTRACT FROM AUTHOR]

A problem is raised for the introduction rules proposed in Benjamin Schnieder’s (2011) ‘A logic for “because”’, arising in connection with (a) inferences that the rules should not, but do, validate and (b) inferences that the rules should, but do not, validate. [ABSTRACT FROM AUTHOR]

The main purposes in the essay are to introduce applied logic as a re search area, to situate it in a broader context, to make the case that it is a significant and worthwhile enterprise, and to detail some of its research areas. [ABSTRACT FROM AUTHOR]

This article gives an interpretation and justification of extensional and intensional conjunction in the relevant logic R. The interpretive frameworks are Anderson and Belnap's natural deduction system and the theory of situated inference from Mares, Relevant Logic. [ABSTRACT FROM PUBLISHER]

Following Neale, I call the notion that there can be no such thing as a structured referring expression ‘structure skepticism’. The specific aim of this paper is to defuse some putative counterexamples to structure skepticism. The general aim is to bolster the case in favor of the thesis that lack of structure—in a sense to be made precise—is essential to reference. [ABSTRACT FROM AUTHOR]

Heidegger believes that logic concerns the meaning of a sentence and the content of judgment. The development of mathematical logic makes logic lose its significance and depart from the ontological discussion. Philosophical logic is not a new discipline but has just realized the characterization of the traditional logic, and also a deviant logic different from mathematical logic. Through studying the relationship between logic and philosophy, we obtain a deeper understanding toward the nature of logic and the relationship between different logical systems. The formal differentiation of different logical systems helps us better clarify the philosophical concept and explain it more accurately. In studying philosophical logic and the philosophy of logic,we must keep it in mind that logic needs philosophical justification and philosophy is the basis of the study of logic. Philosophical logic is the application of logic in philosophy and the philosophical idea has been inculcated deeply in this process of application. [ABSTRACT FROM AUTHOR]

This paper reports the introduction of electronic handsets, like those used on the television show ‘Who Wants To Be A Millionaire?’ into the teaching of philosophical logic. Logic lectures can provide quite a formidable challenge for many students, occasionally to the point of making them ill. Our rationale for introducing handsets was threefold: (i) to get the students thinking and talking about the subject in a public environment; (ii) to make them feel secure enough to answer questions in the lectures because the system enabled them to do this anonymously; and (iii) to build their confidence about their learning by their being able to see how they were progressing in relation to the rest of the students in the class. We have achieved all of these and more. Our experience has revealed that the use of handsets encourages a more dynamic form of student interaction in an environment – the lecture – that can, in the wrong hands, be utterly enervating, but they also provide an opportunity for the lecturer to respond to students' difficulties at the time when they really matter. In this paper, we discuss our case of rapid adoption, our grounds for judging it a success, and what that success seems to have depended on. [ABSTRACT FROM AUTHOR]

My discussion addresses the differences between analytic and continental philosophy concerning the use of logic and exact reasoning in philosophical practice. These differences are mainly examined in the light of the controversial dominance of Hegel's concept of logic (and theory of concept) in twentieth-century continental philosophy. The inquiry is developed in two parts. In the first (Sections 1-2), I indicate some aspects of the analytic-continental divide, pointing to the role that the topic 'logic and philosophy' plays in it. In the second part (Sections 3-6), I give a short account of the views of logic which are typical of the three main trends of continental philosophy (see Table 1). I also suggest how, with the aid of some typical analytical devices, some continental 'anti-logical' attitudes may be corrected, on their own terms. [ABSTRACT FROM AUTHOR]

There is the idea that rational belief for a single individual can be constructed via a process of unilateral argument. To preempt antipathy between the AI communities that can claim the idea that rational belief can be so constructed, we trace the idea to the beginning of this century, to Keynes' dispute with Russell over logic and probability. We review how Keynesian ideas were revived in AI's work on non-monotonic reasoning and parallel developments in philosophical logic. [ABSTRACT FROM AUTHOR]