Talk given at the Séminaire interuniversitaire de Logique et Ontologie, Namur.
Abstract. The prima facie case for considering "informational semantics" as an alternative explication of the notion of logical consequence alongside the model-theoretical and the proof-theoretical one is easily summarised. Where the model-theory is standardly associated with a defence of classical logic (CL), and proof-theory with a defence of intuitionist logic (IL), informational semantics seems to be wedded to relevant and other substructural logics (RL). As such, if the CL, IL, RL trio is a representative chunk of a broader range of logical options, informational semantics surely has its place. Yet, it is even easier to dismiss the suggestion that informational semantics provides an apparently missing third conception of logical consequence. After all, isn't it just a variant of the usual interpretation of the Routley-Meyer relational semantics rather than a genuine alternative to a model-theoretic account? Or worse, isn't it a mere metaphor? In the present paper, we want to consider a more subtle answer to the question of whether informational semantics is a real alternative for the two more traditional contenders. Our discussion undoubtedly leaves many questions unanswered. We mainly try to give the reader an idea of why informational semantics is a genuine and attractive alternative. To that end, we sketch two complementary pictures of the informational approach to logical consequence: a traditional model-theoretic one, and a more abstract one based on the inverse relation between logical discrimination and deductive strength.
