Walter mysteriously wrote
given (i[f] p then q) and not-q, it follows that not-q.
Maybe in some possible world it does but not in this one. It does seem clear however that 'not-q' entails 'not-q,' one of the more notable advances in logic since Chrysippus.
Robert Paul ------------------------------------------------------------------ To change your Lit-Ideas settings (subscribe/unsub, vacation on/off, digest on/off), visit www.andreas.com/faq-lit-ideas.html