Russell and Maccoll : Reply to Grattan-Guinness, WoleŃski, and Read

Abstract

In the December 1999 special edition of Nordic Journal of Philosophical Logic on Hugh MacColl, Ivor Grattan-Guinness and Jan Wolenski describe my discussions of Russell and MacColl in superficially true but unfortunately misleading ways. After replying to them, I proceed to my main topic, whether we can impute S5 to MacColl in light of Stephen Read's paper in the same special edition denying that MacColl has S4 or even S3. I argue that MacColl has an S5 formal modal logic with invariant formal certainties and impossibilities, and following Read, a T material modal logic with material certainties and impossibilities which can vary relative to fresh data, and that MacColl writes these logics using the same generic notation.