Re: "Set Theory: Constructive and Intuitionistic ZF" on SEP

On Sat, 21 Feb 2009 07:27:26 -0800 (PST), greeneg@xxxxxxxxxxxxx wrote:


On Sat, 21 Feb 2009 05:19:42 -0800 (PST), LudovicoVan
As a side note, related to some well known discussions usually going
on in this group, here is a quote that I find "interesting" -- the
very terminology is indeed enough to conclude that this author must be
an incompetent and a liar, surely to be banned from any teaching:

On Feb 21, 8:42 am, David C. Ullrich <dullr...@xxxxxxxxxxx> wrote:
Why would that be? I

WHAT is with this BULL***??
You UNDERSTAND PERFECTLY well why that would be!

I don't see anything below that's obviously false.

Yet, precisely as he said, WE HAVE seen LOUD denunciations
HERE of people who presume to defend "potential infinity"!

For the sake of consistency I should really call you a LIAR here.
He has not said anything about "potential infinity" - or rather
he didn't in the original post, which is what I was replying to;
complaining that my comment ignored things he said _later_
is a little curious.

THOSE are the "well known discussions" being alluded to!
AND THEY ARE *WELL* known, INCLUDING *TO YOU*!!

Really?

Give a link to a thread where I've said anything at all
about the distinction between potential and actual
infinity. Or a thread that gives any evidence that I've
paid any attention at all to the discussions of that
question.

And also give a link to a thread where someone has
been loudly denounced for talking about this distinction,
_where_ there was no _other_ nonsense in the thread,
like a proof that ZF is inconsistent or that the power set
of N is countable or whatever.

Is there, say, somewhere else in the article where he
claims to have proved ZF is inconsistent or something?

What else may be in the article IS NOT THE ISSUE!
THE ISSUE is that "potential infinity"

Precisely what in the original post shows that that IS
THE ISSUE?

and its adherents HERE
HAVE BEEN ATTACKED in ways somewhat INcompatible with
the level of RESPECTABLE "support" and "endorsement" (for THEIR
ideas) that they COULD be claiming from this article!
(Not that they are smart enough to know how to claim it, but)
The POINT is, when the article says that BROUWER
"abandoned classical logic and embarked on an ambitious programme to
renovate the whole mathematical landscape. He denounced that classical
logic had wrongly been extrapolated from the mathematics of finite
sets, had been made independent from mathematics, and illicitly
applied to infinite totalities"
HOW IN THE HELL are you (or I, or anyone) supposed to get away with
attacking
WM
for saying and doing THE SAME thing??

Does it explain in that article that an infinite binary tree
must have only countably many branches since it has
only countably many nodes? If so I missed it. If not
I'm missing your point.

Obviously, he does it badly.
Obviously, there are lots of OTHER things in his presentation to
object to,
besides this. Obviously, he never said he was disavowing classical
logic
RIGHT ALONG WITH "actual" infinity.
But THE POINT is, this article clearly invites that discussion to
proceed
along some track OTHER Than just automatically dismissing WM et al
in the way they have historically been dismissed here!

Again, point out a thread where "potential infinity" is the
only "controversial" aspect, and where people are denounced
for talking about it.

THAT IS,
PRECISELY
as LV says, "interesting", IF you had any interest in the potential
infinity threads to begin
with.

Why would you imagine I do have any such interest, and why should I?

But you SHOULD have ALREADY known all that WITHOUT anyone NEEDING
to explain it to you. And IF you already knew it then there WOULD BE
NO WAY
you could have, in good faith, have asked your question in reaction to
LV here.

Over and over people here and on sci.math complain that
people won't allow people to consider alternatives to
standard theories. That's simply not so - mathematicians
and logicians just love to consider alternatives, they
do it all the time. What's not allowed is making false
statements, in particular invalid claims of proofs of this
or that.

If the likes of Brouwer have already done something that has been
dismissed
here, then you are going to stand convicted of splitting hairs at best
and
hypocrisy at worst. Nobody has the power to allow or disallow
anything
in any case. False statements have A LOT of value in this context;
they
are basically the grit around which the pearl of a cogent corrective
public explanation (WHICH IS ALWAYS A GOOD thing) can form.

The point is that nowhere around HERE have you seen anybody
conceding that maybe Brouwer was on to something

Huh? Who around here has insisted that he was NOT onto something?

What are YOU on, by the way? Your grasp of REALITY seems
to be a little shaky today.

or that
maybe WM understood that. This article invites that, and that
is INTERESTING AND NEW compared to what has recently
been going on here.


I obviously don't expect WM or any of the other cranks to be
intellectually competent to take advantage of the opportunity,
but I do expect something more than fake befuddlement
from the likes of you and AK.


David C. Ullrich

"Understanding Godel isn't about following his formal proof.
That would make a mockery of everything Godel was up to."
(John Jones, "My talk about Godel to the post-grads."
in sci.logic.)
David C. Ullrich

"Understanding Godel isn't about following his formal proof.
That would make a mockery of everything Godel was up to."
(John Jones, "My talk about Godel to the post-grads."
in sci.logic.)
.

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