Xuefeng Wen

Date: December 6, 2023
Time: 11:00 am - 12:00 pm
Location: ICT 616

Title: A Ternary Notion of Logical Consequence

Abstract:¬†Slightly altering and extending McGee’s semantics for conditionals, we define a ternary notion of logical consequence for the validity of natural language arguments.¬† The ternary logical consequence can be regarded as a unification of two kinds of validity in the literature. By the new notion of logical consequence, an inference is not just valid or invalid, but valid or invalid under a set of assumptions. Based on this notion, we give a unified solution to some typical puzzles concerning conditionals and epistemic modals, including the (in)validity of modus ponens, modus tollens, Import-Export, conditional excluded middle, Or-to-If, and fatalism arguments, as well as the puzzle of Moore sentences and the scope ambiguity problem in modal conditionals.

Slides: https://www.dropbox.com/scl/fi/fsdv9ake54sjaukqujtiv/P-ternaryValidity-UC.pdf?rlkey=3gofcsdycmyt7jo6gt8cexlgb&dl=0