The is an old question over whether there is a substantial disagreement between advocates of different logics, as they simply attach different meanings to the crucial logical terminology. The purpose of this article is to revisit this old question in light a pluralism/relativism that regards the various logics as equally legitimate, in their own contexts. We thereby address the vexed notion of translation, as it occurs between mathematical theories. We articulate and defend a thesis that the notion of “same (...) meaning” is itself context-sensitive, depending on the purposes of a given conversation. (shrink)

In this paper I discuss a prevailing view by which logical terms determine forms of sentences and arguments and therefore the logical validity of arguments. This view is common to those who hold that there is a principled distinction between logical and nonlogical terms and those holding relativistic accounts. I adopt the Tarskian tradition by which logical validity is determined by form, but reject the centrality of logical terms. I propose an alternative (...) framework for logic where logical terms no longer play a distinctive role. This account employs a new notion of semantic. (shrink)

Alfred Tarski's (1936) semantic account of the logical properties (logical consequence, logical truth and logical consistency) makes essential appeal to a distinction between logical and non-logical terms. John Etchemendy (1990) has recently argued that Tarski's account is inadequate for quite a number of different reasons. Among them is a brief argument which purports to show that Tarski's reliance on the distinction between logical and non-logical terms is in principle mistaken. According (...) to Etchemendy, there are very simple (even first order) languages for which no such distinction can be made. This is a surprising result, and an important one, if true. Since Tarski's account does indeed depend on such a distinction, Etchemendy's argument, if correct, would rule out definitively the received view on logical truth (as well as logical consequence and logical consistency). But his argument is not correct, and it is the job of this paper to show that. (shrink)

The essay discusses a recurrent criticism of the isomorphism-invariance criterion for logical terms, according to which the criterion pertains only to the extension of logical terms, and neglects the meaning, or the way the extension is fixed. A term, so claim the critics, can be invariant under isomorphisms and yet involve a contingent or a posteriori component in its meaning, thus compromising the necessity or apriority of logical truth and logical consequence. This essay shows (...) that the arguments underlying the criticism are flawed since they rely on an invalid inference from the modal or epistemic status of statements in the metalanguage to that of statements in the object-language. The essay focuses on McCarthy’s version of the argument, but refers to Hanson and McGee’s versions as well. (shrink)

According to the classical invariance criterion, a term is logical if and only if its extension is isomorphism-invariant. However, a number of authors have devised examples that challenge the sufficiency of this condition: accepting these examples as logical constants would introduce objectionable contingent elements into logic. Recently, Gil Sagi has responded that these objections are based on a fallacious inference from the modal status of a sentence to the modal status of the proposition expressed by that sentence. The (...) present paper demonstrates that Sagi’s response, though successful, is futile. There is another objection, based on the same type of example, that is not susceptible to Sagi’s criticism: accepting the examples as logical terms would have the fatal consequence that any contingent metalanguage sentence is entailed by the truth of some logically true object-language sentence. I conclude with a sketch of an alternative to the classical invariance criterion. (shrink)

A volume integrating various parts of Fred Sommer's theory on logic and the philosophy of language and also extending it in a variety of ways, such as semantics and modal logic.

Many of the earliest books, particularly those dating back to the 1900s and before, are now extremely scarce and increasingly expensive. We are republishing these classic works in affordable, high quality, modern editions, using the original text and artwork.

First published in the most ambitious international philosophy project for a generation; the _Routledge Encyclopedia of Philosophy_. _Logic from A to Z_ is a unique glossary of terms used in formal logic and the philosophy of mathematics. Over 500 entries include key terms found in the study of: * Logic: Argument, Turing Machine, Variable * Set and model theory: Isomorphism, Function * Computability theory: Algorithm, Turing Machine * Plus a table of logical symbols. Extensively cross-referenced to help (...) comprehension and add detail, _Logic from A to Z_ provides an indispensable reference source for students of all branches of logic. (shrink)

We analyse the behaviour of definite descriptions and proper names terms in mathematical logic. We show that in formal arithmetic, wether some axioms are fixed or not, proper names cannot be considered rigid designators and have the same behaviour as definite descriptions. In set theory, sometimes two names for the same object are introduced. It seems that this can be explained by the notion of meaning. The meaning of such proper names can be considered as fuzzy sets of equivalent (...) co-designative definite descriptions and their references as sets of all equivalent co-designative definite descriptions. (shrink)

Many powerful logics exist today for reasoning about multi-agent systems, but in most of these it is hard to reason about an infinite or indeterminate number of agents. Also the naming schemes used in the logics often lack expressiveness to name agents in an intuitive way.To obtain a more expressive language for multi-agent reasoning and a better naming scheme for agents, we introduce a family of logics called term-modal logics. A main feature of our logics is the use of modal (...) operators indexed by the terms of the logics. Thus, one can quantify over variables occurring in modal operators. In term-modal logics agents can be represented by terms, and knowledge of agents is expressed with formulas within the scope of modal operators. (shrink)

Any logic is represented as a certain collection of well-orderings admitting or not some algebraic structure such as a generalized lattice. Then universal logic should refer to the class of all subclasses of all well-orderings. One can construct a mapping between Hilbert space and the class of all logics. Thus there exists a correspondence between universal logic and the world if the latter is considered a collection of wave functions, as which the points in Hilbert space can be interpreted. The (...) correspondence can be further extended to the foundation of mathematics by set theory and arithmetic, and thus to all mathematics. (shrink)

The present study starts from the question if there can be any logic of religion. The answer is affirmative for logic in a wide sense. The attempts from the logic of beliefs account for this. However, the study focuses on the specific of the logic of religious terms, a less approached domain by logicians and philosophers. In this line issues like those of the logic of analogy, of the distinctions between the specific, general and total content of terms, (...) between logical distributive and collective conjunctions, etc are brought into discussion. In the end, dogmatic concepts are analyzed, as the core of religious concepts. (shrink)

The paper shows that in the Art of Thinking (The Port Royal Logic) Arnauld and Nicole introduce a new way to state the truth-conditions for categorical propositions. The definition uses two new ideas: the notion of distributive or, as they call it, universal term, which they abstract from distributive supposition in medieval logic, and their own version of what is now called a conservative quantifier in general quantification theory. Contrary to the interpretation of Jean-Claude Parienté and others, the truth-conditions do (...) not require the introduction of a new concept of ‘indefinite’ term restriction because the notion of conservative quantifier is formulated in terms of the standard notion of term intersection. The discussion shows the following. Distributive supposition could not be used in an analysis of truth because it is explained in terms of entailment, and entailment in terms of truth. By abstracting from semantic identities that underlie distribution, the new concept of distributive term is definitionally prior to truth and can, therefore, be used in a non-circular way to state truth-conditions. Using only standard restriction, the Logic’s truth-conditions for the categorical propositions are stated solely in terms of (1) universal (distributive) term, (2) conservative quantifier, and (3) affirmative and negative proposition. It is explained why the Cartesian notion of extension as a set of ideas is in this context equivalent to medieval and modern notions of extension. (shrink)

This paper is an attempt to show that my work to establish numerically flexible quantifiers for the syllogism can be aptly combined with the term logic advanced by Sommers, Englebretsen, and others.

The more passages one examines in the translations from Arabic to Latin and from Arabic to English and other modern languages, the more mistakes one comes across in the translation of the Arabic expression ‘alā al-qaṣd al-awwal . The mistakes stem from the failure to distinguish between two senses of the expression, one an adverb, and the other a famous philosophic concept. Failing to distinguish between the two senses, the translators translated the phrase literally, often with unsatisfactory results. In this (...) paper, I shall indicate a Greek word which was rendered by the Arabic ‘alā al-qaṣd al-awwal. I shall refer to some English translations from the Arabic and show how wrong they are. I shall suggest that in Arabic philosophy itself al-Fārābī, rather than Avicenna, may have been the origin of the philosophic concepts of “first and second intentions.” I shall point out that although these concepts may have been introduced into Latin scholasticism by Raymond Lull, he could not have derived them from the Logic of al-Ghazālī, as has been alleged. (shrink)

abstract. A first-order dynamic epistemic logic is developed where the names of the agents are also terms in the sense of first-order logic. Consequently one can quantify over epistemic modalities. Us- ing constructs from dynamic logic one can express many interesting concepts. First-order update models are developed and added to the language as modalities.

A clausal logic allowing to handle term-graphs is defined. Term-graphs are a generalization of terms (in the usual sense) possibly containing shared subterms and cycles. The satisfiability problem for this logic is shown to be undecidable (not even semi-decidable), but some fragments are identified for which it is semi-decidable. A complete (w.r.t validity) calculus for these fragments is proposed. Some simple examples give a taste of this calculus at work.

This paper shows that the non-Boolean logic of quantum measurements is more naturally represented by a relatively new 4-operation system of Boolean fractions—conditional events—than by the standard representation using Hilbert Space. After the requirements of quantum mechanics and the properties of conditional event algebra are introduced, the quantum concepts of orthogonality, completeness, simultaneous verifiability, logical operations, and deductions are expressed in terms of conditional events thereby demonstrating the adequacy and efficacy of this formulation. Since conditional event algebra is (...) nearly Boolean and consists merely of ordered pairs of standard events or propositions, quantum events and the so-called “superpositions” of states need not be mysterious, and are here fully explicated. Conditional event algebra nicely explains these non-standard “superpositions” of quantum states as conjunctions or disjunctions of conditional events, Boolean fractions, but does not address the so-called “entanglement phenomena” of quantum mechanics, which remain physically mysterious. Nevertheless, separating the latter phenomena from superposition issues adds clarity to the interpretation of quantum entanglement, the phenomenon of influence propagated at faster than light speeds. With such treacherous possibilities present in all quantum situations, an observer has every reason to be completely explicit about the environmental–instrumental configuration, the conditions present when attempting quantum measurements. Conditional event algebra allows such explication without the physical and algebraic remoteness of Hilbert space. (shrink)

An accessible guide for those facing the study of Logic For The first time, this book covers key thinkers, terms and texts.

The problem of empty terms is one of the focal issues in analytic philosophy. Russell’s theory of descriptions, a proposal attempting to solve this problem, attracted much attention and is considered a hallmark of the analytic tradition. Scholars of Indian and Buddhist philosophy, e.g., McDermott, Matilal, Shaw and Perszyk, have studied discussions of empty terms in Indian and Buddhist philosophy. But most of these studies rely heavily on the Nyāya or Navya-Nyāya sources, in which Buddhists are portrayed as (...) opponents to be defeated, and thus do not truly reflect Buddhist views on this issue. The present paper will explore how Dignāga, the founder of Buddhist logic, deals with the issue of empty subject terms. His approach is subtle and complicated. On the one hand, he proposes a method of paraphrase that resembles Russell’s theory of descriptions. On the other, by relying on his philosophy of language—the apoha theory, he tends to fall into a panfictionalism. Through the efforts of his follower Dharmakīrti, the latter approach would become more acceptable among Indian and Tibetan Buddhists. Dignāga’s Chinese commentators, who were free from the influence of Dharmakīrti, dealt with the empty term issue in three ways: (1) by adhering to Dignāga’s method of paraphrase; (2) by allowing exceptions for non-implicative negation; and (3) by indicating the propositional attitude of a given proposition. Among these, the third proved most popular. (shrink)

This paper attempts to demonstrate that the logical problematic of signification, has a very dangerous socio-political effect due to the ontological implication that is connected to the signification of terms in logic. It expounds the notion of signification in Formal Logic as exposed by William of Ockham. It thus, employs this notion of signification of terms, to discuss the term “Fulani”, to show the danger potent in distorting the signification of the term “Fulani” as in every conventional (...) and connotative terms. This work claims that as a result of the connection between logic and ontology, conceptualization and perception, names and reality, the distortion of terms, which are the building blocks of propositions in logic could lead to a dangerous cognition and perception of ontological realities. To this end, it posits a critique on the dangerous change in the signification of the term “Fulani”, in the conceptualization and perception of present day Nigeria people, of West Africa. A dangerous change, as this paper claims, if not speedily reconstructed and re-conceptualized, could lead to a disastrous situation in the socio-political reality of the Nigerian State. (shrink)

In this paper, a theory T H based on combining type freeness with logic is introduced and is then used to build a theory of properties which is applied to determiners and quantifiers.

We define when a ternary term m of an algebraic language \ is called a distributive nearlattice term -term) of a sentential logic \. Distributive nearlattices are ternary algebras generalising Tarski algebras and distributive lattices. We characterise the selfextensional logics with a \-term through the interpretation of the DN-term in the algebras of the algebraic counterpart of the logics. We prove that the canonical class of algebras associated with a selfextensional logic with a \-term is a variety, and we obtain (...) that the logic is in fact fully selfextensional. (shrink)

In this paper we 1. provide a natural deduction system for full first-order linear logic, 2. introduce Curry-Howard-style terms for this version of linear logic, 3. extend the notion of substitution of Curry-Howard terms for term variables, 4. define the reduction rules for the Curry-Howard terms and 5. outline a proof of the strong normalization for the full system of linear logic using a development of Girard's candidates for reducibility, thereby providing an alternative to Girard's proof using (...) proof-nets. (shrink)

I subscribe to and defend frege's view that concepts are essentially predicative such that they can never occur as subjects of predication, Arguing against recent contentions of geach and strawson to the effect that (a) some general terms can so occur; (b) that 'anything whatever' can be a subject of predication. I discuss in detail frege's treatment of universally quantified propositions, Particular propositions, And unquantified propositions arguing that his thesis can be defended in each type of case.

Given some links between Lyndon’s Interpolation Theorem, term distribution, and Sommers and Englebretsen’s logic, in this contribution we attempt to capture a sense of interpolation for Sommers and Englebretsen’s Term Functor Logic. In order to reach this goal we first expound the basics of Term Functor Logic, together with a sense of term distribution, and then we offer a proof of our main contribution.

The question of whether knowledge is definable in terms of belief, which has played an important role in epistemology for the last 50 years, is studied here in the framework of epistemic and doxastic logics. Three notions of definability are considered: explicit definability, implicit definability, and reducibility, where explicit definability is equivalent to the combination of implicit definability and reducibility. It is shown that if knowledge satisfies any set of axioms contained in S5, then it cannot be explicitly defined (...) in terms of belief. S5 knowledge can be implicitly defined by belief, but not reduced to it. On the other hand, S4.4 knowledge and weaker notions of knowledge cannot be implicitly defined by belief, but can be reduced to it by defining knowledge as true belief. It is also shown that S5 knowledge cannot be reduced to belief and justification, provided that there are no axioms that involve both belief and justification. (shrink)

One can construct a mapping between Hilbert space and the class of all logic if the latter is defined as the set of all well-orderings of some relevant set (or class). That mapping can be further interpreted as a mapping of all states of all quantum systems, on the one hand, and all logic, on the other hand. The collection of all states of all quantum systems is equivalent to the world (the universe) as a whole. Thus that mapping establishes (...) a fundamentally philosophical correspondence between the physical world and universal logic by the meditation of a special and fundamental structure, that of Hilbert space, and therefore, between quantum mechanics and logic by mathematics. Furthermore, Hilbert space can be interpreted as the free variable of "quantum information" and any point in it, as a value of the same variable as "bound" already axiom of choice. (shrink)