Paul Rubin <http://[EMAIL PROTECTED]> wrote:
> "Fredrik Lundh" <[EMAIL PROTECTED]> writes: > > A: are there any blue cars on the street? > > B: no. not a single one. > > A: you're wrong! all cars on the street are blue! > > B and A are both correct. It's just logic ;-). Charles Lutwidge Dodgson spent his professional life arguing against this, as I mentioned in <http://mail.python.org/pipermail/python-list/2001-July/052732.html> -- but, mostly, "mainstream" logic proceeded along the opposite channel you mention. Good thing he had interesting hobbies (telling stories to children, and taking photographs), or today he perhaps might be remembered only for some contributions to voting-theory;-). I don't know of any "complete and correct" logic (or set-theory) where there is more than one empty-set, but I'm pretty sure that's because I never really dwelled into the intricacies of modern theories such as modal logic (I would expect modal logic, and intensional logic more generally, would please Dodgson far better than extensional logic... but, as I said, I don't really understand them in sufficient depth)... Alex -- http://mail.python.org/mailman/listinfo/python-list
