[lit-ideas] Re: Ruth Barcan Marcus 1921-2012
- From: "palma@xxxxxxxxxx" <palmaadriano@xxxxxxxxx>
- To: lit-ideas@xxxxxxxxxxxxx
- Date: Sat, 17 Mar 2012 21:11:59 +0200
maybe when you have the time, you may want to check, a theorem is the
ordinally last line of an ordered string. each line is either an axiom or
it is derived from anything preceding it. hence either you find that the
derivation of the Barcan formula is incorrect or not. there is nothing to
object.
a false theorem is the santa claus that keeps tormenting your infantile
nightmares, namely isN'T
I am sure some further objection will be presented by illustrating the
objection to Pythagoras' theorem or to the infinity of primes.
If you are worried about examples, i would suggest the excellent Aigner M &
Ziegler G, "Proofs from the BOOK" Berlin, 2000
You may then present objections.
On what you "say" there is nothing in the Barcan formula that even mentions
actual "individuals"
the formula is
[image: \forall x \Box Fx \rightarrow \Box \forall x Fx]
no more and no less, and as pointed out earlier, it is derivable in a
complete logic (much work on it was done not coincidentally by Ruth Barcan)
אַ פֿריילעכן פּסח
On Sat, Mar 17, 2012 at 4:43 PM, Donal McEvoy <donalmcevoyuk@xxxxxxxxxxx>wrote:
>
> *From:* Adriano Palma Palma@xxxxxxxxxx
> > >the Barcan formula is a theorem, it is impossible to detect what your
> "objection" is supposed to be
> >>
>
>
> If the two clauses above are connected [e.g. as it's a theorem it cannot
> be that there is any objection], then I would suggest even theorems can be
> false and can be objected to.
>
> If the clauses are not connected and the point is simply that an objection
> cannot be detected then
>
> (a) what is the relevance of saying 'the Barcan formula is a theorem'?
>
> (b) my post was an attempt to put what I understood to be the logical
> point at issue in ordinary language, and to pass comment that it would seem
> that "if all actual humans must die it does not necessarily follow that all
> possible humans must die...(unless we deem all actual humans to exhaust the
> category of all possible humans)".
>
> The point at (b) raises a number of questions - like whether this is an
> accurate way to convey the logical point at issue in ordinary language and
> whether the logical point depends on what we "deem" as the relation between
> "actual humans" and "all possible humans". These questions are not answered
> by pointing out that 'Barcan's formula is a theorem' or asserting that 'an
> objection cannot be detected'.
>
> So much so that the point of the post is one that is hard for me to
> detect.
>
> Donal
> London
> **
>
>
>
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--
palma, KZN
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