Re: Fitch's paradox and OWA

Marshall says...

>However what I was referring to was specifically
>how they get from step 7 to step 8 within that
>RAA proof. Your response does not seem to
>address that particular issue.

That's exactly the step that I was talking about. Steps (4), (5) and (6) and (7) constitute a proof of ~K(p ∧ ~Kp). Therefore, we have |- ~K(p ∧ ~Kp)

By C, if you have |- f, then you have |- [] f. Letting f = ~K(p ∧ ~Kp), it follows that |- [] ~K(p ∧ ~Kp)
which is step (8).

>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.

--
Daryl McCullough
Ithaca, NY