On 28 Aug, 15:25, Bruno Marchal <marc...@ulb.ac.be> wrote:
> On 28 Aug 2009, at 13:47, Flammarion wrote:
> > On 21 Aug, 20:49, Bruno Marchal <marc...@ulb.ac.be> wrote:
> >> On 21 Aug 2009, at 09:33, Flammarion wrote:
> >>  I can only hope you will work on the UDA+MGA, and understand that
> >> "non-theoretical" truth have to be redefined as theoretical
> >> possibilities (consistencies) observed from inside (from some first
> >> person point of view).
> > There is no UD.
> You are meaning "no physical UD". I don't need a physical UD in the
> reasoning.

I mean no existent UD, material or immaterial

> >>>> Thanks for quoting my sane2004 definition of comp, and showing that
> >>>> indeed platonism is not part of it.
> >>> "It is a version of Platonism"
> >> The wording is not important.
> > Maybe you could flag the wording that we are supposed
> > to take serioulsy.
> I have explained to you why it is preferable to avoid the term
> "Platonism" for the belief that classical logic can be applied in
> arithmetic

I think the term Arithmetical Realism should be avoided when it is not
clear whether it is a claim about truth or about existence.

>. Even mathematicians does not call that Platonism, which
> they use for the general idea that classical logic applies to a much
> larger part of math.  Arithmetical realism is better: it is the belief
> that the truth of arithmetical sentence exists independently of any
> means (humans, theories, machines, universes, ...) to study them.
> >> The point is that in the assumption of
> >> CTM, (CT+ the theological act of faith),  I am using that "version of
> >> platonism" only, which is just the idea that classical logic can be
> >> applied to arithmetical sentences, and in the conclusion, only, we
> >> have to abandon weak materialism or CTM.
> > Nope. Assumptions about truth don't get you a UD which is capable of
> > simulating me. You need
> > a claim about existence.
> You told me this before, and I did explain that I am use the truth of
> the existential statement in arithmetic, as my unique claim about
> existence.

And I put forward the counterargument that you can have
true statements about existence, where the existence in question
is not literal ontological existence. You need to argue that backwards-
means RITSIAR, and not just "existence" in some fictional or formal

> > You argument is either based on Platonism or
> > invalid
> Yes, it based on Turing theorem, which with CT can be sump up by
> "universal digital machines exist".
> >>>> Just arithmetical realism without which CT has no meaning at all.
> >>> The CT thesis requires some mathematical
> >>> claims to be true. it doesn't require numbers to actually exist
> >> I have never asserted that numbers actually exist. Just that they
> >> exist in the sense of the usual interpretation of existential
> >> arithmetical statement are independent of me, you, or the existence
> >> or
> >> not of a material world.
> > There is no usual interpretation, it is disputed.
> For set theoretical realism. Not for the natural numbers.

Yes, for natural numbers. Even the existence of the number
one is disputed among philosophers

> I mean
> nobody, except you and ultrafinitist, doubt about the mathematical
> existence of natural numbers. They can doubt about deeper existence of
> those numbers, but I am not using this. Are you criticizing all
> theories using natural numbers (from economy to physics)?.

As I have pointed out endlessly, I think the standard
backwads-E statements of arithmetic are *true* , I just don't think
backwards-E *means* ontological existence.

> > Formalists don't
> > think
> > backeards-E has any existential implications at all
> Formalist does not believe in primary matter either.

I think most of them do. That claim requires some support
at least.

> And they do
> believe in formal systems,

which *doesn't* mean immaterial systems. Formal systems exist
in mathematician's brain, books, and blackboards for

>which have sense only through naïve
> arithmetic. This dodge the issue, nevertheless, because you can add
> "formal" to all existential quantifier in the reasoning without
> changing the conclusion: formal physics has to be reduced to formal
> number theory.

It does change the conclusions. If the UD does not exist
immaterially, or materially, it does not exist, and therefore I and
are not being simulated on it. You cannot valldly derive an
conclusion without making existential assumptions.

> >> Would the two cosmic branes never have collided, and the big bang
> >> never occurred, the Rieman hypothesis would still be atemporally and
> >> aspatially true or false.
> > Truth and falsehood don't buy you an immaterial computer simulating me
> > and eveything I see.
> Fortunately numbers and math are still free. If CTM is correct, you
> are emulated infinitely often in the UD*. It exists (mathematically)
> like PI and square-root of two.

Which  is to say, it does not really exist at all, and is merely
said to exist in a formal game.

> >>>> Get the feeling you have change your mind on AR. You believe that a
> >>>> proposition like the statement that there is no biggest prime
> >>>> number
> >>>> has something to do with physics. In which physical theory you
> >>>> prove
> >>>> that statement, and how?
> >>> Its truth is not  a physical truth. The existence or non-existence
> >>> asserted is not any kind of real existence
> >> OK, in your theory "real existence" = "physical existence".
> > There are two claim here:
> > "real existence" = "physical existence".
> > and
> > "mathemaical existence" != "real existence".
> > they are argued separately.
> Please, define "real".


> >> But if the
> >> UDA is valid it would be better to write "consensual reality" =
> >> "physical reality", and ontic or basic 3- existence = arithmetical
> >> existence, or to abandon CTM. If UDA is non valid, it would be nice
> >> to
> >> point where is the error. You said that the error is in step 0,
> >> because I would have pretended something like "the number seven
> >> actually exists". My answer is that I don't see where I say so. I
> >> just
> >> say that the number seven exists, in the sense used by
> >> mathematicians.
> >> I limit my "platonism" to arithmetic to avoid the problem of
> >> "platonism" in set theory or analysis, and the CTM explains why
> >> realism on natural numbers in both necessary and sufficient.
> >>> I am not denying nay truths, only the interpretation of backwards-E
> >>> as actual existence
> >> I am using a fairly common notion of mathematical existence,
> > There is no common notion, the ontology of maths is not
> > a settled issue
> The ontology of math is not settled, sure, but this does not prevent a
> common agreement, notably on the mathematical existence of natural
> numbers.

What you are referring to is agreement amongst mathematicians
about which backwards-E statements to accept. That is quite different
form agreement amongst philosophers about the ontological status
of numbers.

> >> and I
> >> explain that once you say yes to the doctor, the notion of physical
> >> existence has to be reduced to that common notion of mathematical
> >> existence (actually a tiny part of arithmetical existence).
> >> Up to now, the only things you criticize in the UD reasoning are
> >> things *you* are introducing,
> > In the sense that your Platonism is largley implict,
> > and needs to be made explicit..
> Where?

Everywhere except where I was able to quote you admitting to it.

> >> and when I remark to you that it is not
> >> there, you say, it is implicit, but fail to show me where those
> >> implicit statement have been used. Then you change the meaning of
> >> "platonism" at every post. You define a criterium of "real" (RITSIAR)
> >> without ever saying if the "I" is the third person body (which we can
> >> doubt the existence) or the first person consciousness (which we
> >> cannot doubt, but can't communicate).
> > From the materialist POV, the difference isn't important.
> >> You said that the difference is
> >> epistemological, but that does not answer the question.
> >> You said once that you accept mathematical truth, and then that the
> >> number seven does not exist AT ALL.
> > It is not some absurdity I just invented.
> I was pointing that you have said successively
> - the number seven exists only mathematically
> - the number seven does not exist at all

YES!!!! Formalism means: mathematical existence == non-existence

> Those are contradictory statements.

No! It is not a contradiction to say Sherlock Holes lived in Baker
street, and Sherlock Holmes was not real at all.
One is true within a "game", the other is true full stop.

> >> You compare mathematical object with fictional character in fairy
> >> tales!
> > That's another well-know position called ficitonalism
> >http://plato.stanford.edu/entries/fictionalism-mathematics/
> There are degrees of fictionalism.
> Strong fictionalism claim that "7 is prime" is false.
> Weak fictionalism still agree that "7 is prime" has most of its usual
> mathematical meaning. This is enough for the reasoning to proceed. A
> weak fictionalist can accept CT.
> No mathematician are strong fictionnalist. It is an idea of
> philosopher only. I accept that the UD reasoning does not work for a
> strong fictionnalist, but this should be obvious from CT.

Weak fictionalism does not buy you an actual, RITSIAR

> >> Do you really think that an arithmetician could write "Once
> >> upon a time there was an odd number dreaming  becoming an even
> >> number ...".
> > That isn't what I wrote. What I wrote was that there are sentences
> > which are a) true and b) mention the word "exists" but in which
> > "exsts" is not meant to be taken literally.
> When discussing fundamental science, no use of the word "exist" should
> be taken literally.

Fine. Then I am not literally being simulated by an immateial UD.

> >> It would help much more if you were able to say "I don't understand
> >> this or that in the reasoning, and give explicit reference to the
> >> paper or posts".
> > The argumetn I am actually making is that your arguemnt is either
> > invalid or has an imiplict premise. How am I supposed ot
> > point to an implicit premise.
> By pointing on a step in the reasoning where you think I am using that
> implicit premise.

That's where you tell me I am being simulated by an immaterial UD

> Bruno
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