Jan Wolenski

Les débats qui ont eu lieu, lors du Congrès de philosophie scientifique de 1935, sur la sémantique et sa portée philosophique présentent un grand intérêt historique pour deux raisons. Tout d’abord, on s’accorde à y reconnaître un des évènements majeurs du congrès. En second lieu, et de façon plus substantielle, ils ont joué un rôle décisif dans le développement de la sémantique comme discipline philosophique. C’est Carnap qui en a pris l’initiative en invitant Tarski à donner deux conférences. Ce sont eux qui, avec Kokoszyńska, deviendront les porte-parole de la sémantique. Neurath, qui a préparé le résumé de la discussion, avait plusieurs objections contre la sémantique à la Tarski. En particulier, il craignait que la sémantique n’introduise la métaphysique dans la philosophie. La suite a montré que les partisans de la sémantique ont gagné.

This paper discusses the concept of nothing (nothingness) from the point of logic and ontology (metaphysics). It is argued that the category of nothing as a denial of being is subjected to various interpretations. In particular, this thesis concerns the concept of negation as used in metaphysics. Since the Leibniz question ‘Why is there something rather than nothing?’ and the principle of sufficient reason is frequently connected with the status of nothing, their analysis is important for the problem in question. Appendix contains a short critical analysis of Heidegger’s famous statement Das Nichts nichtet.

The paper discusses the concept of adequacy central for Pertażycki’s methodology. According to Petrażycki any valuable scientific theory should be adequate, that is, neither limping nor jumping. Consequently, adequacy of a theory is a stronger condition than its truth. Every adequacy theory is true, but not conversely. However, there is problem, because scientific laws are conditionals. This suggests that adequacy is too strong conditions, because the consequence of an implication has a wider scope than its antecedent. Thus, laws should have the form of equivalence. The paper shows how model-theoretic characterization of theories allows to recognize truth and adequacy, consistently with Petrażycki’s claims.

. The classical Liar paradox is as follows We can construct several Liar-like paradoxes, for instance of meaninglesness: An additional principles: A is meaningful  A is meaningful; A is meaningful if and only if A is true or false; is not meaningful; is true  is not meaningful; Assume that is true; hence is not meaningful; but is meaningful as true; Assume that is false; hence is meaningful, but  jest meaningful and true; hence   is meaningful; hence  is not meaningful; hence we return to the former case; Analogical paradoxes can be formulated for rationality, testability, etc. A general lesson: If a principle P establishes meaning of a predicate W referring to properties of sentences such that T-scheme is applicable, we can expect that the predicate in question can generate a Liar-like paradox. However, it does not mean that philosopher must resign from P. Generalizing the truth case P is formulated in ML and apply to items formulated in L. The only moral is that the criteria from L have to be supplemented by something else.

This paper deals with the problem of universality property of logic. At first, this property is analyzed in the context of first-order logic. Three senses of the universality property are distinguished: universal applicability, topical neutrality and validity. All theses senses can be proved to be justified. The fourth understanding, namely the amount of expressive power, is connected with the criticism of the first-order thesis: first-order logic is the logic. The categorical approach to logic is presented as associated with the last understanding of universality. The author concludes that two senses of universality should be sharply discriminated and defends the first-order thesis.

Logical theory codifies rules of correct inferences. On the other hand, logical reasoning is typically considered as one of the most fundamental cognitive activities. Thus, cognitive science is a natural meeting-point for investigations about the place of logic in human cognition. Investigations in this perspective strongly depend on a possible understanding of logic. This paper focuses on logic in the strict sense; that is, the theory of deductive inferences. Two problems are taken into account, namely: do humans apply logical rules in ordinary reasoning?; the genesis of logic. The second issue is analyzed from the naturalistic point of view.

This paper analyses proofs of impossibility of epistemology formulated by Leonard Nelson. He proposed two such demonstrations. The first proof tries to show that no criterion of knowledge is possible. Nelson's second argument considers the sentence B 'A is a piece of knowledge' as being synthetic. On the other hand, Epistemology cannot employ problematic premises. Hence, it consists of analytic sentences. Now, epistemology is impossible because synthetic sentence cannot be derived from purely analytic ones. The analysis conducted in the papers intends to locate Nelson's arguments in contemporary discussions about the status of epistemology. In particular, it is argued that the second proof deserves attention of contemporary epistemologists.

Gaunilo argued that Anselm could prove the existence of many perfect objects, for example, the happiest island, that is, happier than any other island. More formally, Gaunilo’s arguments were intended to show that the sentence “God exists‘ does not follow from premises accepted by Anselm. Contemporary versions of the ontological proof use the maximalization procedure in order to demonstrate that God exists as the most perfect being. This paper argues that this method, which is based on maximalization, is not sufficient to prove God’s existence. Thus, a “contemporary Gaunilo‘ can repeat objections raised by his ancestor.

Ancien etudiant de Brentano et de Zimmerman, Kazimierz Twardowski, apres son election a la chaire de philosophie a Lvov en 1895, crea autour de lui un cercle d'etudiants et de collaborateurs exceptionnel, connu aujourd'hui sous le nom d'Ecole de Lvov-Varsovie. A mi-chemin entre Vienne et Cambridge, c'est a Lvov, et puis partiellement a Varsovie, que Jan Lukasiewicz, Stanislaw Lesniewski, Alfred Tarski, Kazimierz Ajdukiewicz, Tadeusz Kotarbinski et bien d'autres encore, repenserent dans un esprit d'analyse les questions fondamentales de la philosophie du langage, de la logique, de la philosophie des sciences et des mathematiques. Plus qu'une simple traduction, ce livre est une version revisee de la monographie desormais classique que Jan Wolenski, connu pour ses travaux non seulement en histoire de la philosophie analytique, mais aussi en epistemologie et en theorie de la verite, a consacree a l'Ecole de Lvov-Varsovie.

This paper proposes a formal framework for the cognitive relation understood as an ordered pair with the cognitive subject and object of cognition as its members. The cognitive subject is represented as consisting of a language, conequence relation and a stock of accepted theories, and the object as a model of those theories. This language allows a simple formulation of the realism/anti-realism controversy. In particular, Tarski’s undefinability theorem gives a philosophical argument for realism in epistemology.

Formal semantics is understood either as a formal analysis of semantical features of natural language or as model-theoretic semantics of formal(ized) languages. This paper focuses on the second understanding. The problem is how to identify the formal aspects of formal semantics, if we understand ‘formal’ as ‘independent of content’. This is done by showing that the form of semantical interpretation of a language L is given by its syntax and the parallelism of the signature of L and its interpretative structure SI. However, the content of interpretation, that is, the way of correlating of L-expressions with extralinguistic items depends of informal factors. The discussion shows that semantics is prior to syntax