A letter to The Times of London, May 9, 1992 protesting the Cambridge University proposal to award an honorary degree to M. Jacques Derrida.

A comparative study of a broad range of logical systems, showing that classical logic is just one among them and thate there are useful nonclassical logics which are conservative extensions of classical logic, by risorting to several negations and several implications. The book is oriented towards a defense of fuzzy logics.

Still, it is but fair for me to point out that several of the mainstays of the present proposal owe very little to the influence of the philosophers whose epistemological views have attracted me most — or for that matter to that of other analytical philosophers. I am referring to my acknowledging degrees of truth and existence and, consequently, degrees of knowledge, too.

Graham Priest's book In Contradiction is a bold defense of the existence of true contradictions. Although Priest's case is impressive, and many of his arguments are correct, his approach is not the only one allowing for true contradictions. As against Priest's, there is at least one contradictorialist approach which establishes a link between true contradictions and degrees of truth. All in all, such an alternative is more conservative, closer to mainstream analytical philosophy. The two approaches differ as regards the floodgate (...) problem. Priest espouses a confinement policy banning contradictions except in a few special domains, particularly those of pure semantics and set-theory , whereas the alternative approach admits two negations -- natural or weak negation and strong negation, the latter being classical; accordingly, the alternative approach prohibits any contradiction involving strong negation, thus providing a syntactic test of what contradictions have to be rejected. (shrink)

This is a critical discusssion of Professor da Costa's Essay on the foundations of logic which brings up issues of philosophy of logic, set theory, the foundations of mathematics, and paraconsistency.

The main starting point of many of the contributions collected into the book is the kind of Twin Earth considerations, along with meaning individualism. Is Putnam's claim about water in this world and a stuff in an alternative world being different materials?. Is meaning in the head? One seems allowed to be skeptical about the starting point of the debate between such as emphasize broad content and those who think that the basic semantic entities are narrow contents, which would fail (...) to be world-dependent or world-oriented. The kind of motivations prompting the essays collected into the book are likely to be regarded as in need of a deeper elucidation by such as have been more or less influenced by Quine. Pettit & McDowell's collection of essays is one of the books most scholars interested in the confines of philosophy of language and philosophy of mind will find worth reading. (shrink)

In his 1686 essay GI Leibniz undertook to reduce sentences to noun-phrases, truth to being. Such a reduction arose from his equating proof with conceptual analysis. Within limits Leibniz’s logical calculus provides a reasonable way of surmounting the dichotomy, thus allowing a reduction of hypothetical to categorical statements. However it yields the disastrous result that, whenever A is possible and so is B, there can be an entity being both A and B. Yet, Leibniz was in the GI the forerunner (...) of 20th century combinatory logic, which (successfully!) practices - sometimes for reasons not entirely unlike Leibniz’s own grounds - reductions of the same kinds he tried to carry out. (shrink)

7 pages.-- Delivered to: 5th International Conference on Argumentation, The International Society for the Study of Argumentation, University of Amsterdam, 25-28 June 2002.

Many-Valued logics can harbour nonclassical connectives expressing truth-nuances. The course of development of many-valued logics has given rise to paraconsistent systems wherein a sentence can be both negated and asserted just in case it is only partly true. A recently implemented family of such logics is shown to be a useful tool in coping with a number of philosophical difficulties, such as Zeno’s paradox of the arrow. This family is somehow akin to fuzzy logics initiated by Zadeh, but unlike them (...) it contains as a tautology the principle of excluded middle. (shrink)

A Fuzzy-Set Theoretical Framework -resting on a paraconsistent infinite-valued logic- is sketched, wherein a thorough ontological-reduction program can be carried out. The framework includes formulae of the form “x comprises z in the time-interval e”. Reducing aggregates to sets thus handled is shown to escape usual objections. Likewise, systems generally can be regarded as aggregates, hence as (fuzzy) sets -the purported nonextensionality of systems objection being disposed of owing to our system’s recognizing infinitely many membership degrees. So do bodies, too, (...) which enables us to find a solutionto Unger’s sorites concerning ordinary material bodies. (shrink)

Orayen proposes some kind of intensional approach in philosophy of logic, with meanings playing a central role in implementing the notion of logical truth. Orayen regards Quine as his main interlocutor. The major topic gone into through the book is logical form, validity and logical truth. As an outgrowth, Quine's operationalist view of language receives an extensive coverage and discussion. The investigation into the notion of logical truth and validity leads to a critical assessment of the relevantist challenge to the (...) classical conception. This critical notice casts doubt on Orayen's defence of analyticity as a requirement for logical truth. (shrink)

The paper examines Beuchot's approach and agrees that there are many coincidences between medieval Aristotelianism and analytical philosophy. Both pursue philosophical inquiry in an argumentative manner. Nowadays analytical philosophy also tends to recognize as genuine such traditional metaphysical problems as were debated by the Scholastics. The paper's only criticism at Beuchot's views concerns analogy and reduplicative as-clauses. It argues that on that issue the cleavage between medieval and analytical philosophy lies in the latter's tending to favor complete equivocality of the (...) word «being». However, an alternative is possible, namely univocism, as implemented in combinatory logics, which while also rejecting reduplicative clauses is free from the ineffableness attendant upon equivocism. (shrink)

Introductory Remarks Why Paradigm Variation is Ensuant upon Contradiction How Externalistic Warrant Parries the Threat of [Truth] Relativism Why Not to Ward Relativism off by Means of Foundationalistic Justification Defending a relativistic View of Warrant A Transcendental Argument against [Truth] Relativism Towards [Partial] convergence A Gradualistic Paraconsistent Way to Convergence 7.1. - Perspectivism and Non Copulative Paraconsistent Logics 7.2. - The Strength and Weakness of Two Copulative Approaches to Paraconsistent Logic 7.3. - The Logic of Contradictorial Gradualism 7.4. - Implementing (...) the Notion of Relative Truth Bibliographic References.. (shrink)

Da Costa's paraconsistent systems of the series Cm (for finite m) (see [C1], [C2], and esp. [C3], pp. 237ff.) share important features with transitive logic, TL (which has been gone into in [P1] and [P2]), namely, they all coincide in that: (c1) they possess a strong negation, `¬', a conditional, `⊃', a conjunction, `∧', and a disjunction, `∨', with respect to which they are conservative extensions of CL or Classical Logic; (c2) they possess a non strong negation, `N' (notations are (...) different for systems C) which does not possess all properties of classical negation, but for which the following schemata are theorematic (I use the letters `p', `q', etc as schematic letters; my notational conventions are basically Church's: associativity leftwards; a dot stands for.. (shrink)

En este trabajo estudio algunas de las convergencias y divergencias entre dos concepciones filosóficas que coinciden en reconocer la contradictorialidad de lo real, o sea: que coinciden en ser dialécticas. Trátase de la filosofía de Hegel y de la concepción que en muy diversos trabajos y desde hace años vengo denominando ontofántica, concepción cuya aceptación de la contradictorialidad de lo real se sitúa más en la línea de Platón que en la de Hegel.

In his 1686 essay GI Leibniz undertook to reduce sentences to noun-phrases, truth to being. Such a reduction arose from his equating proof with conceptual analysis. Within limits Leibniz’s logical calculus provides a reasonable way of surmounting the dichotomy, thus allowing a reduction of hypothetical to categorical statements. However it yields the disastrous result that, whenever A is possible and so is B, there can be an entity being both A and B. Yet, Leibniz was in the GI the forerunner (...) of 20th century combinatory logic, which (successfully!) practices - sometimes for reasons not entirely unlike Leibniz’s own grounds - reductions of the same kinds he tried to carry out. (shrink)

¿Están comprendidos los extranjeros en el ámbito de aplicación de los derechos y deberes fundamentales estipulados por las constituciones modernas? Lamentablemente, no. Ha habido, a lo largo de la historia, progresos y retrocesos en la conciencia jurídica de los derechos migratorios. Hoy tienden a establecerse cláusulas de libre circulación en los espacios de integración económica, al paso que, de manera general , viene prohibida la inmigración del sur al norte. Esa orientación actual es injusta. Ni se atiene a un principio (...) de justicia natural ni respeta la tradición jurídica . Es dudoso que tengan los estados derecho a prohibir la inmigración foránea. Menos aún es admisible que se considere un delito el auxilio a la inmigración no autorizada. Frente a los criterios hoy imperantes, este artículo formula la propuesta de reconocer el derecho universal humano de migración por todo el Planeta. (shrink)