Re: Fitch's paradox and OWA(B

Jan Hidders <hidders_at_gmail.com> writes:

> On 1 jan, 05:26, stevendaryl3..._at_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.