From: George Greene on
On Jun 6, 2:31 am, Transfer Principle <lwal...(a)lausd.net> wrote:
> Therefore, any poster who doesn't like Cantor's Theorem
> ought to consider NFU instead of ZFC.

Nobody ought to consider NFU period for any but the most theoretical
of reasons.
For example, in NFU, the set of all 1-element subsets of a set is NOT
the same
size as the set! You canNOT prove the existence of the function
mapping x to {x}
for every x in some domain-set S.

What you really want to consider, far more generically than NFU,
is set theory with a universal set. There are plenty of web-pages
devoted.


From: Aatu Koskensilta on
Transfer Principle <lwalke3(a)lausd.net> writes:

> I am confident that ZF is consistent, because I believe that if ZF
> were inconsistent, a proof of this would have been found by now.

Why? This is not uncommon idea but on closer scrutiny there's not much
to recommend it.

> If it does turn out that ZF is inconsistent, then there would have
> been some underlying reason that the proof wasn't discovered for over
> a century after the axioms were first given.

What's there to rule out the possibility that the simplest proof of a
contradiction in ZF is inhumanely complex, utterly beyond our
comprehension, invoking, say, an obscure instance of
Pi-20^20^20^20^4546^3214532 + 4145624^7542 + 897412 replacement?

--
Aatu Koskensilta (aatu.koskensilta(a)uta.fi)

"Wovon man nicht sprechan kann, dar�ber muss man schweigen"
- Ludwig Wittgenstein, Tractatus Logico-Philosophicus
From: Bill Taylor on
On Jun 9, 1:32 pm, Aatu Koskensilta <aatu.koskensi...(a)uta.fi> wrote:

> What's there to rule out the possibility that the simplest proof of a
> contradiction in ZF is inhumanely complex, utterly beyond our
> comprehension, invoking, say, an obscure instance of
> Pi-20^20^20^20^4546^3214532 + 4145624^7542 + 897412 replacement?

Common sense?

-----------------------------------------------------
Bill Taylor W.Taylor(a)math.canterbury.ac.nz
-----------------------------------------------------
Q. Why did the chicken cross the Moebius strip?

A: To get to... to...
-----------------------------------------------------
From: Aatu Koskensilta on
Bill Taylor <w.taylor(a)math.canterbury.ac.nz> writes:

> Common sense?

How does common sense rule out the possibility that the simplest proof
of a contradiction in ZF is inhumanely complex?

--
Aatu Koskensilta (aatu.koskensilta(a)uta.fi)

"Wovon man nicht sprechan kann, dar�ber muss man schweigen"
- Ludwig Wittgenstein, Tractatus Logico-Philosophicus
From: |-|ercules on
"Aatu Koskensilta" <aatu.koskensilta(a)uta.fi> wrote ...
> Bill Taylor <w.taylor(a)math.canterbury.ac.nz> writes:
>
>> Common sense?
>
> How does common sense rule out the possibility that the simplest proof
> of a contradiction in ZF is inhumanely complex?
>

The question of the decade!

hint: common sense will easily refute most of the popular derivations of ZF.

IF ZF told you to jump off a cliff would you?

Herc