Path: news.cambrium.nl!textnews.cambrium.nl!feeder2.cambriumusenet.nl!feed.tweaknews.nl!195.96.0.7.MISMATCH!newsfeed.utanet.at!newsfeed.straub-nv.de!feeder.eternal-september.org!eternal-september.org!not-for-mail From: "Jesse F. Hughes" Newsgroups: comp.databases.theory,sci.logic,sci.philosophy.tech Subject: Re: Fitch's paradox and OWA Followup-To: sci.logic Date: Fri, 01 Jan 2010 12:36:22 -0500 Organization: The Eternal (and Int'l) Order of Palsy-Walsies -- President Message-ID: <874on5d8x5.fsf@phiwumbda.org> References: <4919dc70-6375-432e-b2aa-2f7c1b3c15ba@n31g2000vbt.googlegroups.com> <736f25ee-d0d4-4c10-807a-247776181f8e@h9g2000yqa.googlegroups.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-2022-JP-2 Injection-Date: Fri, 1 Jan 2010 17:40:02 +0000 (UTC) Injection-Info: news.motzarella.org; posting-host="CAkdWTyV2QkPm9OCI4Y3ZA"; logging-data="24920"; posting-account="U2FsdGVkX192GFXN9bjnnmiyfmVbch8f" User-Agent: Gnus/5.110006 (No Gnus v0.6) XEmacs/21.4.21 (linux) Cancel-Lock: sha1:BR6x7STpAf4mTVKgvnsP1q3aa9E= sha1:BHXs2U9A8nyFKnfsAlfnjOnSGVY= Xref: news.cambrium.nl sci.logic:158637 comp.databases.theory:38103 Jan Hidders writes: > On 1 jan, 05:26, stevendaryl3...@yahoo.com (Daryl McCullough) wrote: >> Marshall says... >> >> >Are your comfortable with how step 8 is >> >obtained from step 7 via Rule C as described >> >on this page? >> >http://plato.stanford.edu/entries/fitch-paradox/ >> >> Yes, that's exactly what they are doing. They >> didn't use the |- symbol in step 7, but it is >> clear that (7) is the conclusion of a proof. > > Wow. You are right. They correctly conclude in (7) that |- ~K(p & ~Kp). > > Hmm. I need to think this over. I'm beginning to believe now that the > inference in the paradox is in fact correct. But of course it's correct! Fitch's paradox is perfectly non-controversial, as a matter of purely formal reasoning. It's well-known and well studied by logicians. It would be truly remarkable if you found an error in a famous formal proof of under a dozen lines. -- "The papers are currently at journals. [When published,] make no mistake, there will be no place on this planet where you can hide. Remember, I'm not talking about something vague here. I'm talking about publication in journals." James S. Harris. Wow. Journals.