Jan Wolenski

This paper presents and discusses Henri Poincaré’s view on the logical non-derivability of imperatives from indicatives. Firstly, his point of view is compared with David Hume’s. Then Poincaré’s thesis is shown to have been implicitly or explicitly essential to attempts to build a logic of imperatives (norms) as a special linguistic category as well as a deontic logic. The paper shows deontic logic enables us to formulate general principles concerning the logical separability of deonticals (sentences with deontic operators) and non-deontic sentences. Finally, the paper includes remarks on the reception of Poincaré’s discussed ideas in later logical and philosophical literature with the second issue illustrated by legal philosophy.

This paper compares Kotarbiński’s reism and naturalism. It argues that basic ontological and epistemological reistic principles fit naturalism very well. In particular, the thesis claiming that there are only spatiotemporal things (bodies) gives a very simple naturalistic account of reality. Radical realism defended by Kotarbiński is a version of direct realism, a view about perception which is very accurate for naturalism. On the other hand, since difficulties of reism are also problems for naturalism, the former illuminates typical challenges for the latter

Formal semantics is understood either as a formal analysis of semantical features of natural language or as model‐theoretic semantics of formal 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.

Poland has played an enormous role in the development of mathematical logic. Leading Polish logicians, like Lesniewski, Lukasiewicz and Tarski, produced several works related to philosophical logic, a field covering different topics relevant to philosophical foundations of logic itself, as well as various individual sciences. This collection presents contemporary Polish work in philosophical logic which in many respects continue the Polish way of doing philosophical logic. This book will be of interest to logicians, mathematicians, philosophers, and linguists.

The problem of induction belongs to the most controversial issues in philosophy of science. If induction is understood widely, it covers every fallible inference, that is, such that its conclusion is not logically entailed by its premises. This paper analyses so-called reductive induction, that is, reasoning in which premises follow from the conclusion, but the reverse relation does not hold. Two issues are taken into account, namely the definition of reductive inference and its justification. The analysis proposed in the paper employs metalogical tools. The author agrees with the view that a quantitative account of degree of confirmation for universal theories via logical probability is problematic. However, prospect for a qualitative approach look as more promising. Using the construction of maximally consistent sets allows to distinguish good and worthless induction as well as shows how to understand induction in a semantic way. A closer analysis of deductivism in the theory of justification shows that it is a hidden inductivism.

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.