Re: Mathematical Logic, Podnieks'page ...

2004-07-04 Thread Bruno Marchal
At 06:57 03/07/04 -0400, John M wrote:
(Bruno: am I still in your corner?)
OK. Let us see.
Dear Kory, an appeal to your open mind: in the question whether
we discovered math or invented it...,
many state that the first version is 'true'.
Beside the fact that anybody's 'truth' is a first person decision,

Then I would decide to have food when I am hungry, to have water
when I am thirsty. I would decide Riemann hypothesis true and even proved 
by me,
and I would decide to get those million dollars.
I would decide you to be a platonist, my friend, ...
I would decide peace everywhere,
 ...if truth was a matter of first person *decision*.
Seriously, I am afraid you confuse the luckily adequate first person feeling
the first person lives in front of truth and truth itself.


the fact
that anything we may know (believe or find), is interpreted by the ways
how our 'human' mind works -

SURE!  (but it is invalid to infer from that that truth itself depends on 
our beliefs,
and findings).


including comp and all kinds of computers, as
we 'imagine' (interpret, even formulate) the thoughts.
I find the above distinction illusorical. We may FIND math as existing
'before' we constructed it, or we may FIND math a most ingenious somersault
of our thinking.

Then you will miss the discovery that a big part of math and
actually the whole of physics is a most ingenuous somersault of the
universal machine thinking.
(and the discovery that comp imply that in a testable manner)

To 'believe' that 17 is prime? of course, within the ways as we know (and
formulate) the concept 'prime'. Axioms, conventions.

Are you not confusing sentences/theories with proposition/truth?
Read Wilfrid Hodge Penguin's Logic page 39. (I can quote it if you insist).

With the ideas about 'quite' different universes why are we closed to the
idea of 'quite' different mathematical thinking?

Because for some reason we are (or we will be) studying different sort of
mathematical thinking, and so, to avoid confusion, it is better to agree
at the start on the elementary principle we share. Logic, is the science
of different thinking, actually. Boolean (classical) logic is the simplest 
to use
in math (but not the simplest to describe in boolean logic because
the similarity of the object and the subject ...)


We don't have to go to another universe: the Romans subtracted in their
calendar (counting backwards from the 3 fixed dates in a month) like minus
1 = today, minus 2 = yesterday and so on.
I wonder how would've done that Plato (before the invention of 0)?
Our list-collegues think about math(s) in quite different concepts  from the
classic 'constructivist(?)' arithmetical equational thinking.

Should I understand you are realist for intuitionistic arithmetic ? It is 
enough
for the reasoning I propose.


how far can go a quite differently composed mind - maybe in an
organizational thinking/observing system of a universe NOT based on space -
time?

You underestimate the hardness to understand ourselves despite our
probable common space time background.

What can be called 'mathematics'? (Theory(s) of Everything?)

Here you jump to an infinitely difficult and controversial question.
I have criticize Tegmark for relying on that problem. One of the power of
comp is that it made possible to give information on fundamental matter
without needing to define 'mathematics.

Vive le 'scientific agnosticism'!

Right!   (At the condition that this principle does not discourage us to 
propose
theories ...)


(Bruno: am I still in your corner?)

If you really believe truth is just a matter of first person decision, you 
are not.
Neither if you belief the primality of 317 is a matter of convention.
Only the language is (partly) conventionnal, not the proposition, including 
their
intended meaning.
We must agree on a minimal amount of reasoning if only to be able to talk
about others ways of reasoning. If not: it will be confusing from the start.

Bruno


- Original Message -
From: Kory Heath [EMAIL PROTECTED]
To: [EMAIL PROTECTED]
Sent: Friday, July 02, 2004 4:10 PM
Subject: Re: Mathematical Logic, Podnieks'page ...
 At 02:45 PM 7/2/2004, Jesse Mazer wrote:
 As for the non-constructivism definition, is it possible to be a
 non-constructivist but not a mathematical realist? If not then these
 aren't really separate definitions.

 It may be that all non-constructivists are mathematical realists, but some
 constructivists are mathematical realists as well (by my definition of
 mathematical realism). So Platonism == mathematical realism and
 Platonism == non-constructivism are two different statements. I can
 imagine a non-constructivist asking Are you a Platonist? (thinking Do
 you accept the law of excluded middle?), and a constructivist answering
 Yes. (thinking, yes, valid constructive proofs are valid whether or not
 any human knows them or believes them.) This miscommunication will lead
to
 confusion later in their conversation.

 -- Kory



Re: Mathematical Logic, Podnieks'page ...

2004-07-04 Thread Bruno Marchal
At 14:20 03/07/04 -0400, Kory Heath wrote:

Yes, but some confusions are so easy to avoid! Confusions will always 
appear in the middle of conversations, but I want them at least to be 
unexpected ones...! Anyway, I didn't mean to derail the conversation with 
my jargoning; I was just pointing out that whenever I see platonism in 
one of these conversations, I'm never sure what we're really talking about.

No problem. Let us use arithmetical realism, (for the belief that any 
(close) arithmetical
formula is either true or false, independently of us). I mean first order 
logic formula ... for those who know what I mean (cf Podnieks page if some 
wants to know that urgently).

Now I recall the problem: by UDA physics (in world/state /situation A) is 
given by a measure on all computationnal histories going through A and as 
seen from A.

The strategy I have followed consist to ask a sound universal machine what 
she thinks about that question. I translate the world/state/situation A 
by a (finite or infinite) set of provable (DU accessible) arithmetical 
propositions, and I translate all computationnal histories by the set of 
all maximal consistent extensions of A. Then I show that the measure one 
or probability one propositions p must satisfy the following conditions:
1) to be true everywhere (= true in all maximal consistent extensions, = []p)
2) to be true somewhere (= true in some consistent extensions, = p)
   (by Godel 1) does not imply 2) from the machine in A perspective!)
This is enough to prove that the probability 1 is quantum like. The 
miracle comes from the
strange and counter-intuitive behavior of the Godel beweisbar (provability) 
[] predicate.

Bruno


http://iridia.ulb.ac.be/~marchal/


Re: Mathematical Logic, Podnieks'page ...

2004-07-04 Thread John M
Dear Bruno, let me segment your long reply (thanks) and reflect now in the
1st part to your comments on truth. (I may come to the others later, I
just beware of milelong posts).
I interleave my response.
John Mikes

- Original Message -
From: Bruno Marchal [EMAIL PROTECTED]
To: [EMAIL PROTECTED]
Sent: Sunday, July 04, 2004 10:32 AM
Subject: Re: Mathematical Logic, Podnieks'page ... (1st part)
 At 06:57 03/07/04 -0400, John M wrote:

 (Bruno: am I still in your corner?)

 OK. Let us see.

 Dear Kory, an appeal to your open mind: in the question whether
 we discovered math or invented it...,
 many state that the first version is 'true'.
 Beside the fact that anybody's 'truth' is a first person decision,

 Then I would decide to have food when I am hungry, to have water
 when I am thirsty. I would decide Riemann hypothesis true and even proved
 by me, and I would decide to get those million dollars.
 I would decide you to be a platonist, my friend, ...
 I would decide peace everywhere,
   ...if truth was a matter of first person *decision*.
 Seriously, I am afraid you confuse the luckily adequate first person
feeling
 the first person lives in front of truth and truth itself.

JM:
I think we got into a semantic quagmire. I feel a different meaning in my
(5th language English) TRUTH from what I read as the (4th language French)
'verité'. I use 'truth' as the OPINION one accepts as being not false. What
you imply sounds to me as 'constructing a reality. Truth has nothing to do
with decisionmaking. Decision comes into the picture only in the 1st
person thinking to decide whether the item is not false. If I agree, it is
(my) truth as well.

 the fact
 that anything we may know (believe or find), is interpreted by the ways
 how our 'human' mind works -

 SURE!  (but it is invalid to infer from that that truth itself depends on
our beliefs and findings).

Sorry, Bruno, you sound in the parethetized remark as a person who believes
in some eternal 'truth' chisled in the (nonexistent) stone of (nonexistent)
supernatural 'law', - or rather: takes something like 'truth' as the
installations (facts??)of the world. There is no such thing as THE TRUTH  -
ITSELF at least not among people who think... Maybe some religious fanatic
fundamentalists know the truth, the only ONE, worthwhile killing (-dying)
for.
Even the facts are explanations for observations - and we saw lately
discussions on observers.
The flat Earth: a fact (Ptolemaios), hell: a fact (A. Dante), the atoms in
the molecules I synthesized: facts, then all these things turned into
fiction. Props of some belief system.

Now let me take a deep breath and if I am still 'on' this list, later I will
come back to 'math'.
(I don't know Wilfried Hodge, will not read him for this purpose.)

Till then, I celebrate July 4th

John Mikes

 SNIP the rest