4 ideas
10053 | Geometrical axioms imply the propositions, but the former may not be true [Russell] |
10052 | Geometry is united by the intuitive axioms of projective geometry [Russell, by Musgrave] |
490 | Everything happens by reason and necessity [Leucippus] |
7006 | Observing irrelevant items supports both 'all x are y' and 'all x are non-y', revealing its absurdity [Schofield,J] |