Philosophy Now Forum

Let □ be the operator "it is provable in ZFC". Let 'P' mean that the Continuum Hypothesis is the case. Take the following Natural Deduction argument in GL provability logic: 1.□(~□P→(□P→P) Theorem Intro. (Prop. Logic) 2.□(~□~P→(□~P→~P)) Theorem Intro. (Prop. Logic) 3.□~□P→□(□P→P) 1, Distri...