From: Virgil on
In article <1159724522.879743.47440(a)e3g2000cwe.googlegroups.com>,
Han.deBruijn(a)DTO.TUDelft.NL wrote:

> William Hughes schreef:
>
> > mueckenh(a)rz.fh-augsburg.de wrote:
> > > If logic and set theory clash, abandon set theory.
> >
> > Indeed, but logic and set theory do not clash.
> > Set theory and intuition about infinite sets
> > clash.
>
> Then abandon _both_ (formal / mathematical) logic _and_ set theory.
>
> Han de Bruijn

Better yet , retrain your intuition about sets, or suppress it entirely
and merely follow where the logic leads.
From: Han de Bruijn on
mueckenh(a)rz.fh-augsburg.de wrote:

> This is the typical one-eyed view of a set theorist. The same we have
> with Han's vase: Of course there is no ball which has not jumped out at
> noon. We cannot name any such number. But the other eye should see that
> there are more balls in than out at any time, including noon. The
> refore set theory is useless. One cannot calculate meaningfully with
> infinites!

Affirmative, of course. One little side note: it's not "Han's vase".
The original poster is by Theo Jacobs, who initiated a thread called
"infinity":

http://groups.google.nl/group/sci.math/msg/d2573fcb63cbf1f0?hl=en&

Han de Bruijn

From: Han de Bruijn on
Virgil wrote:

> My logic and my set theory get along famously.

Please, Virgil, show us some of your famous work.

Han de Bruijn

From: William Hughes on

William Hughes wrote:
> Han.deBruijn(a)DTO.TUDelft.NL wrote:
> > William Hughes wrote:
> >
> > > Han.deBruijn(a)DTO.TUDelft.NL wrote:
> > > > William Hughes schreef:
> > > >
> > > > > mueckenh(a)rz.fh-augsburg.de wrote:
> > > > > > If logic and set theory clash, abandon set theory.
> > > > >
> > > > > Indeed, but logic and set theory do not clash.
> > > > > Set theory and intuition about infinite sets
> > > > > clash.
> > > >
> > > > Then abandon _both_ (formal / mathematical) logic _and_ set theory.
> > >
> > > We are left with intuition. Fine. Oh by the way
> > > we are going to use my intuition. If you don't like
> > > it, too bad. Only I can tell what my intuition is.
> >
> > Better read better the add-on between parentheses.
> > We are left with common speech logic and no set theory.
>
> O.K. Call it what you want. But if you and I do not
> agree on what common sense is, I am right.

For example: It's common sense that you can't put more
than an infinite number of balls in a vase. So if you remove
an infinite number of balls there are no balls left.

-William Hughes
>
> -William Hughes

From: Han de Bruijn on
William Hughes wrote:

> William Hughes wrote:
>
>>Han.deBruijn(a)DTO.TUDelft.NL wrote:
>>
>>>William Hughes wrote:
>>>
>>>>Han.deBruijn(a)DTO.TUDelft.NL wrote:
>>>>
>>>>>William Hughes schreef:
>>>>>
>>>>>>mueckenh(a)rz.fh-augsburg.de wrote:
>>>>>>
>>>>>>>If logic and set theory clash, abandon set theory.
>>>>>>
>>>>>>Indeed, but logic and set theory do not clash.
>>>>>>Set theory and intuition about infinite sets
>>>>>>clash.
>>>>>
>>>>>Then abandon _both_ (formal / mathematical) logic _and_ set theory.
>>>>
>>>>We are left with intuition. Fine. Oh by the way
>>>>we are going to use my intuition. If you don't like
>>>>it, too bad. Only I can tell what my intuition is.
>>>
>>>Better read better the add-on between parentheses.
>>>We are left with common speech logic and no set theory.
>>
>>O.K. Call it what you want. But if you and I do not
>>agree on what common sense is, I am right.
>
> For example: It's common sense that you can't put more
> than an infinite number of balls in a vase. So if you remove
> an infinite number of balls there are no balls left.

I don't think there is any common sense about the infinite.

Han de Bruijn