Ideas from 'Symbolic Logic (with Langford)' by C.I. Lewis [1932], by Theme Structure

green numbers give full details    |     back to texts     |     unexpand this idea


10. Modality / B. Possibility / 8. Conditionals / a. Conditionals
Modal logic began with translation difficulties for 'If...then'
                        Full Idea: C.I.Lewis began his groundbreaking work in modal logic because he was concerned about the unreliability of the material conditional as a translation of 'If ... then' conditionals.
                        From: report of C.I. Lewis (Symbolic Logic (with Langford) [1932]) by Rod Girle - Modal Logics and Philosophy 12.3
                        A reaction: Compare 'if this is square then it has four corners' with 'if it rains then our afternoon is ruined'. Different modalities seem to be involved. We even find that 'a square has four corners' will be materially implied if it rains!