NOL Seminar with Dag Westerståhl
published: 2023-10-09
event date:
2023-10-30
The Nordic Online Logic Seminar
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Date: Monday, 30 October 2023, at 16:00 CET (UTC+1) on Zoom
Speaker: Dag Westerståhl (Stockholm University, Tsinghua University)
Title: From consequence to meaning—the case of intuitionistic propositional logic (IPL)
Abstract
One quarter of the talk presents background on how facts about entailments and
non-entailments can single out the constants in a language, and in particular on
an idea originating with Carnap that the standard relation of logical
consequence in a formal language should fix the (model-theoretic) meaning of its
logical constants. Carnap’s focus was classical propositional logic (CPL), but
his question can be asked for any logical language. The rest of the talk gives a
very general positive answer to this question for IPL: the usual IPL consequence
relation does indeed determine the standard intuitionistic meaning of the
propositional connectives, according to most well-known semantics for IPL, such
as Kripke semantics, Beth semantics, Dragalin semantics, topological semantics,
and algebraic semantics.