Recent work on the development of a dialogical approach to the logic of fiction stresses the notion of existence as choice. Moreover, this approach to existence has been combined with the notion of ontolog-ical dependence as deployed by A. Thomasson’s artifactual theory of fiction. In order to implement such a combination within the dialogical frame several predicates of ontological dependence have been de-fined. However, the definition of such predicates seems to lean on a model-theoretic semantics for mod-al logic after all. (...) The main aim of the present paper is to set a dialogical frame for the study of fictions in the context of the dialogical approach of CTT recently developed by S. Rahman and N. Clerbout where a fully-interpreted language is unfolded. We will herewith develop the idea that in such a setting fiction-al entities are understood as hypothetical objects, that is, objects (functions) the existence of which is dependent upon one or more hypotheses that restrict the scope of choices available. We will finish the paper by suggesting that this provides both a natural and genuinely dialogical way to understand R. Frigg’s take on scientific models as fictions and a new perspective on Thomasson’s notion of generic ontological dependence. Keywords: fiction, dialogues, dialogical logic, hypothetical objects, scientific models. (shrink)

This paper compares Peirce’s and Hintikka’s logical philosophies and identifies a cross-section of similarities in their thoughts in the areas of action-first epistemology, pragmaticist meaning, philosophy of science, and philosophy of logic and mathematics.

Wittgenstein’s language games can be put into a wider service by virtue of elements they share with some contemporary opinions concerning logic and the semantics of computation. I will give two examples: manifestations of language games and their possible variations in logical studies, and their role in some of the recent developments in computer science. It turns out that the current paradigm of computation that Girard termed Ludics bears a striking resemblance to members of language games. Moreover, the kind of (...) interrelations that are emerging could be scrutinised from the viewpoint of logic that virtually necessitates game-theoretic conceptualisations, demonstrating the fact that the meaning of utterances may, in many situations, be understood as Wittgenstein’s language games of ‘showing or telling what one sees’. This provides motivation for the use of games in relation to logic and formal semantics that some commentators have called for. Many of the ideas can be traced to C.S. Peirce, for whom signs were vehicles of strategic communication. The conclusion about Wittgenstein is that the notions of saying and showing converge in his late philosophy. (shrink)

The theory of existential graphs, which Peirce ultimately divided into four quadrants , is a rich method of analysis in the philosophy of logic. Its $$\upbeta $$ β -part boasts a diagrammatic theory of quantification, which by 1902 Peirce had used in the logical analysis of natural-language expressions such as complex donkey-type anaphora, quantificational patterns describing new mathematical concepts, and cognitive information processing. In the $$\upbeta $$ β -quadrant, he came close to inventing independence-friendly logic, the idea of which he (...) found indispensable in fulfilling the tasks –. (shrink)

As a celebration of theTractatus100th anniversary it might be worth revisiting its relation to the later writings. From the former to the latter, David Pears recalls that “everyone is aware of the holistic character of Wittgenstein’s later philosophy, but it is not so well known that it was already beginning to establish itself in theTractatus” (The False Prison, 1987). From the latter to the former, Stephen Hilmy’s (The Later Wittgenstein, 1987) extensive study of theNachlasshas helped removing classical misconceptions such as (...) Hintikka’s claim that “Wittgenstein in thePhilosophical Investigationsalmost completely gave up the calculus analogy.” Hilmy points out that even in theInvestigationsone finds the use of the calculus/game paradigm to the understanding of language, such as “in operating with the word” (Part I, §559) and “it plays a different part in the calculus”. Hilmy also quotes from a late (1946) unpublished manuscript (MS 130) “this sentence has use in the calculus of language”, which seems to be compatible with “asking whether and how a proposition can be verified is only a particular way of asking ‘How do you mean?’” Central in this back and forth there is an aspect which seems to deserve attention in the discussion of a semantics for the language of mathematics which might be based on (normalisation of) proofs and/or Hintikka/Lorenzen game-dialogue: the explication of consequences. Such a discussion is substantially supported by the use of the open and searchableThe Wittgenstein Archives at the University of Bergen. These findings are framed within the discussion of the meaning of logical constants in the context of natural deduction style rules of inference. (shrink)