El cálculo proposicional se basa proposiciones que son tautologías, antilogías y de tipo contingente, construidas con las operaciones de disyunción, conjunción, y negación, así como con el llamado condicional material para trasladar los enunciados condicionales. Con todo ello se obtiene una estructura de álgebra de Boole, que permite equiparar el cálculo proposicional al cálculo algebraico booleano. En parte, la simplificación conceptual que se obtiene resulta de ser el orden parcial del álgebra equivalente a la afirmación del condicional material. Además, con (...) tal metodología cabe ver qué partes del cálculo proposicional clásico pueden trasladarse, aun con limitaciones, a estructuras más débiles y, a la vez, más generales, como son los ortoretículos no booleanos o las álgebras de De Morgan.El cálculo proposicional trata con la deducción. Por ello, el artículo lo desarrolla a partir de un operador de consecuencias en el sentido de Tarski. Ampliado el modelo deductivo, es fácil ver otras consecuencias que las usualmente consideradas en los textos elementales; en particular, se analizan cuatro esquemas de razonamiento deductivo típicos y, entre ellos, se presta especial atención a los usuales Modus Ponens y Modus Tollens. En el caso de las estructuras algebraicas de conjuntos ‘borrosos’, ninguna es de álgebra de Boole ni siquiera de orto-retículo y sólo cabe trabajar, en algunos casos, con álgebras de De Morgan-Kleene. Por lo tanto el cálculo proposicional ‘fuzzy’ debe construirse de acuerdo con la estructura algebraica que corresponda en cada caso y una vez elegida como representación del condicional una función que verifique el Modus Ponens. (shrink)

‘Reasoning’ can be considered a general concept that, upon speaking, is the ‘enraonar’, a Catalan word that should not be mistaken with ‘explain’ nor with ‘discuss’ which imply more detail, and cover different situations. This article is presented as an essay on the ancient ideal of ‘enraonar’. To that end, it is explained in what sense ‘enraonar’ and reason are one of the most complex phenomena thought has to deal with. Here it is argued that these natural phenomena require a (...) systematic and ‘scientific’ study, and that withoutthis knowledge computer science cannot simulate people’s every-day ‘enraonar’. (shrink)

El objetivo de este trabajo es reconsiderar el punto de vista defendido por los pensadores que se pueden adscribir al famoso ‘Círculo de Viena’ sobre el significado y, especialmente, sobre los enunciados asignificativos. Para ello, procedemos usando la típica forma científica, heredera de la tradición del Círculo, de medir empíricamente los conceptos adquiridos. Además, proporcionamos algunas notas históricas, así como algunas reflexiones sobre el pensamiento de Karl Menger sobre la carencia de una geometría adecuada para el micromundo.

: Reasoning’ can be considered a general concept that, upon speaking, is the ‘enraonar’, a Catalan word that should not be mistaken with ‘explain’ nor with ‘discuss’ which imply more detail, and cover different situations. This article is presented as an essay on the ancient ideal of ‘enraonar’. To that end, it is explained in what sense ‘enraonar’ and reason are one of the most complex phenomena thought has to deal with. Here it is argued that these natural phenomena require (...) a systematic and ‘scientific’ study, and that without this knowledge computer science cannot simulate people’s every-day ‘enraonar’. (shrink)

This paper has a very limited scope: it just presents some eIements which may introduce us into a wider investigation on vague predicates. Thus, webegin by pointing out our general conception of Iogic (as a descriptive science of linguistic phenomena). After that, we build up our approach by considering characteristic functions and by trying to make useful the model of logical extension which applies to classical quantifiers.

A través de una serie de ejemplos matemáticos elementales se Ilega a proponer una definición bastante general de Indistinguibilidad, por medio de operadores con valores en semigrupos conmutativos ordenados. Tal definición se aplica a casos provenientes de diversos campos, muchos de los cuales exhiban la propiedad da rotura de las cadenas de objetos relacionados a causa de un cierto parecido.

It can be said that Formal Logic begun by studying an idealization of the statements ’if p, then q’, something coming from long ago in both Greek and Scholastic Philosophy. Nevertheless, only in the XX Century it arrived at a stage of formalization once in 1910 Russell introduced and identified the ’material conditional’ with the expresion ”not p or q”. In 1918, and from paradoxical conditionals like ”If the Moon is a cheese, it is a Lyon’s face”, Lewis critiziced the (...) material conditional and introduced the so-called ’strict conditional’ as the modal necessity of the material one. In 1934, Huntington proved that both material and strict implications are coincidental in the setting of Boolean algebras and, hence, that they only can be actually different in algebraic structures weaker than Boolean algebras. Boolean algebras have too much laws for supporting the difference of both conditionals. This paper is nothing else than an algebraic trial to find simple binary Boolean operations able to express Lewis’ strict implication, and contains a new and simpler proof than that of Huntington, made by identifying ’possible’ with ’non self-contradictory’. By the way, it is shown that this proof is only valid in Boolean algebras, but neither in proper De Morgan algebras, nor in proper Ortholattices, with which it still remains open where the two conditional relations are actually different. (shrink)

This paper deals with the relation with Fuzzy Logic of some of the ideas of Karl Menger published between 1942 and 1966 and concerning what he called “Hazy Sets”, Probabilistic Relations and Statistical Metric Spaces. The author maintains the opinion that if Lofti A. Zadeh is actually the father of Fuzzy Logic, Menger not only was a forerunner of this field but that his ideas were and still are influential on it.