On 21 Aug 2009, at 09:33, Flammarion wrote:

> On 20 Aug, 00:28, Bruno Marchal <marc...@ulb.ac.be> wrote:
>> On 19 Aug 2009, at 22:21, Flammarion wrote:
>>> Where he says computation can happen without any physicial process  
>>> at
>>> all. I don't see any evidence for that
>> I am explaining this right now.
>>> Only Bruno thinks computation trancends matter.
>> The notion of computation and computability have been discovered by
>> Mathematicians working around the foundation crisis of math after the
>> discovery by Cantor and others of paradoxes in set theory.
>> The idea is that computation should be redefined as physical
>> computation is a very recent one, and is due to people like David
>> Deustch and Landauer. And it does not really work as such. Deutsch
>> "reconstruction" of the Post-Church-Turing thesis is really a
>> different thesis.
> Of course you can have theoretical
> truths about computation
> But show me something that has been computed by
> an immaterial computer.

A Schmidhuberian computationalist would probably answer: look around  
you. But I have explained why this is not enough, and why a prori comp  
makes the observable reality not the output of one program (but a view  
from inside from all execution of all programs).

  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).

Comp, or CTM, leads to a "many types no token" view of reality. Token  
are seen as such by being appearances from the point of view of an  
abstract subject coupled to an (infinity of) abstract computations.

>>> CTM *implies* materialism, and the MGA doesn't work.
>> CTM is neutral on materialism, even if many materialist use
>> incorrectly comp to put the mind body problem under the rug. UDA,
>> including MGA, shows why this fails.
>> What is in MGA which does not work?
> It's a reductio of the idea that mental states
> supervene on computational states.
> CTM must be cast as the claim
> that mental activity supervenes on computational
> activity.

I agree. Consciousness is attached to computation (and not to  
computational states), even at the starting of the reasoning, and also  
when the physical supervenience is introduced in MGA for the reductio  
ad absurdum.
Then, eventually, keeping CTM, and thus abandoning (weak) materialism,  
consciousness is related to, well not just a computation, but to an  
infinite sheaves of computations. Consciousness is a first person  
notion, and as such, is dependent on the first person uncertainty  
measure brought by the first person indeterminacy.
This is why I take time to explain what is a computation, or a  
computational activity, in purely arithmetical terms. A computation is  
not "just" a sequence of computational states, it is a sequence of  
computational states related by at least one universal machine (and  
then an infinity of them, from the point of view of the conscious  
being, observably so when he/she looks below its substitution level).  
Classical physics become the study of our most probable computations,  
which emerge from the statistical interference of all computations  
going through my relevant states (the relevance being dependent of the  
observer's comp-substitution level).

>> 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. 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.

>> 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.

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.

>> 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". 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, 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, 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).  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.
You compare mathematical object with fictional character in fairy  
tales! Do you really think that an arithmetician could write "Once  
upon a time there was an odd number dreaming  becoming an even  
number ...".

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".

I would be pleased if you could stop to attribute me more than I make  
explicit. Comp is perhaps just a more precise and much more weak  
assumption than usual CTM theory which usually put the comp level very  
high. Comp is a weak precise form of CTM. And yes, I do believe that 2  
+ 2 = 4, and that 7 is prime.



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