On 14 Aug 2009, at 14:34, 1Z wrote:

> On 14 Aug, 09:48, Bruno Marchal <marc...@ulb.ac.be> wrote:
>> You are dismissing the first person indeterminacy. A stuffy TM can  
>> run
>> a computation. But if a consciousness is attached to that  
>> computation,
>> it is automatically attached to an infinity of immaterial and  
>> relative
>> computations as well,
> There's your Platonism.

Not mine. The one which follows from the comp assumption, if UDA is  

> If nothing immaterial exists (NB "nothing",
> I don't make exceptions for just a few pixies or juse a few numbers)
> there is nothiign for a cosnc. to attach itself to except a propbably
> small, probabuily singular set of stuiffy brains and computers.

I can understand how easy for a materialist it is, to conceive at  
first sight, that numbers and mathematical objects are convenient  
fiction realized as space-time material configuration, perhaps of  
But those space-time configuration are themselves described by  
mathematical functions far more complex that the numbers described or  
explain. This leads to major difficulties, even before approaching the  
consciousness problem.
This shows that a purely physicalist explanation of numbers could lead  
to difficulties. But the same for a description of any piece of  
material things, by just that token.
So, I am not sure that physicist can be said to have solved the  
"matter" problem either, and some physicists are already open,  
independently of comp, to the idea that physical objects are relative  
mathematical (immaterial) objects. Which of course are "no material".  
Wheeler, Tegmark, for example.
But then with comp, you are yourself an immaterial object, of the kind  
person, like the lobian machine. You own a body, or you borrow it to  
your neighborhood, and "you" as an immaterial pattern can become  
stable only by being multiplied in infinities of coherent similar  
histories, which eventually the physicists begin to talk about  

I tend to believe in many immaterial things. Some are absolutely real  
(I think) like the natural numbers.
Some may be seen as absolutely real, or just as useful fiction: it  
changes nothing. This is the case for the negative number, the  
rational, a large part of the algebraic and topological, and analytical.
Some are both absolutely real, and physically real, they live in  
"platonia", and then can come back on earth: they have a relatively  
concrete existence. For example, the games of chess, the computers,  
the animals, and the persons. But the concreteness is relative, the  
'I' coupled with the chessboard is an abstract couple following  
normality conditions (that QM provides, but comp not yet).
Some could have an even more trivial sense of absolute existence, and  
a case could be made they don't exist, even in Platonia, like the  
unicorns, perhaps, and the squared circles (hopefully).

Each branch of math has its own notion of existence, and with comp, we  
have a lot  choice, for the ontic part, but usually I take  
arithmetical existence, if only because this is taught in school, and  
its enough to justified the existence of the universal numbers, and  
either they dreams (if "yes doctor") or at least their discourse on  
their dreams (if you say no the doctor and decide to qualify those  
machines are "inexistent zombies").

There is a sense to say those universal machines do not exist, but it  
happens that they don't have the cognitive abilities to know that, and  
for them, in-existence does not make sense.

And for a mathematicans, they exists in a very strong sense, which is  
that, by accepting Church Thesis, they can prove the existence of  
universal digital (mathematical) machine from 0, succession, addition  
and multiplication.
Both amoebas colony (human cells), and engineers are implementing some  
of them everyday in our neighborhood, as we can guess.



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