Jan Wolenski

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.

Naturalism is the view that only the so-called Natural World that surrounds us exists and that it is knowable by means of general cognitive tools. This has consequences for epistemology, because it determines what is an object of knowledge and how it comes to be known. Epistemological naturalism can be either radical or moderate, granting a certain autonomy to the theory of knowledge with respect to science. The article defends the second position and shows that it justifies the existence of certain problems whose discussion requires going beyond purely scientific data. Nevertheless, naturalized epistemology in any of its forms is incompatible with transcendentalism.

Non-existence provides big problems for ontology and modest for logic. Logical problems of non-existence consist in licensing inferences in which sentences with empty terms are involved. The standard predicate logic solves this question by presupposing that every individual constant has an object to which it refers. This means that empty domains are excluded from semantics for the first-order logic. However, there is a temptation to consider logic without existential presuppositions.The ontological problem of non-existence leads to the question of the meaning of 'nothing'. We encounter "various conceptions of nothing" in the history of philosophy from Parmenides to our times. However, nothing (or nothingness) is always a negation of being. Since we have distributive and collective (mereological) concepts of being, we also should distinguish nothing in the distributive and mereological meaning. This difference is important because only the former leads to the paradox of nothing of all nothings, analogical to the paradox of all sets. A closer analysis of the nothing in the distributive sense shows that any meaningful talk about non-existence requires a relativisation to a fixed domain of discourse. This seems; to entail that the empty set is the formal model of nothing what means that the concept of absolute nothing in the distributive sense is simply inconsistent. To some extent, being and nothing are mutually dual. This motivates that the concept of nothing is governed by so-called dual logic connected with processes of rejection. More specifically, statements on "nothing" are not asserted but rejected.

This papers discuss the place, if any, of Convention T (the condition of material adequacy of the proper definition of truth formulated by Tarski) in the truth-makers account offered by Kevin Mulligan, Peter Simons and Barry Smith. It is argued that although Tarski’s requirement seems entirely acceptable in the frameworks of truth-makers theories for the first-sight, several doubts arise under a closer inspection. In particular, T-biconditionals have no clear meaning as sentences about truth-makers. Thus, truth-makers theory cannot be considered as the semantic theory of truth enriched by metaphysical (ontological) data. The problem of truth-makers for sentences about future events is discussed at the end of the paper.