Le 27-août-06, à 19:36, 1Z a écrit :

>
>
> Bruno Marchal wrote:
>> Le 26-août-06, à 22:44, Brent Meeker a écrit :
>>
>>>  I understand Peters objection to regarding a "mere bundle" of
>>> properties as existent.  But I don't understand why one needs a
>>> propertyless
>>> substrate.  Why not just say that some bundles of properties are
>>> instantiated and
>>> some aren't.
>>
>> I guess Peter needs it for having a notion of (absolute) 
>> instantiation.
>
> If you think, as I do,  that there is a difference between
> logical and physical posibility, you need to explain instantiation.


I do think indeed that there is a difference between logical and 
physical possibility.
The logico-arithmetical possibility for a machine are given by the G 
and G* logics of self-reference. G is for what the machine can tell us 
about that, and G* is for the whole truth (unexpectedly, at the 
propositional level,  this is completely captured by G*).
The physical possibilities are given by the box and diamond of the Z(*) 
and X(*) logics,
The "COMP" physical possibilities are given by the box and diamond of 
the Z1(*) and X1(*) logics. A case can still be given that S4Grz1 plays 
some role there too, but that would make physics closer to the David 
Lyman, George Levy conception; this is testable in principle, but for 
some reason I doubt that this could be possible).


>
> If you think, as I do,  that there is a difference between
> phsyical actuality and physical posibility, you need to explain
> instantiation.

The difference belongs to the person views.


>
> if you think, as rationalists do, that everything possible
> is also necessary and actual, you don't need those
> distinctions.


It is grosso modo, the motto of the everything list!
Of course the comp hyp put restriction on what we can take as possible, 
and it is mainly given by the "true" or "consistent" or both 
restriction. This leads naturally to the hypostases.



>
>> If Peter takes the relative notion of instantiation, which is number
>> theoretical in nature, then he would loose any motivation for his bare
>> matter.
>
> I don't think something can exist in relation to what does not exist.


Nor do I.



> if that is what you mean.


I guess you are doing the confusion I describe in my preceding post.


>
>>>  Anyway, current physical theory is that there is a material
>>> "substrate" which has properties, e.g. energy, spin, momentum,...
>>
>>
>> I doubt this. Yes current *interpretations* of physical theories do
>> suppose a material substrate, but only for having peaceful sleep (like
>> the collapse non-answer in QM).
>
> All theories assume contingency.


? (very vague, I can agree, disagree ...)


>
>> Anyway, the theories does not
>> presuppose it. They presuppose only mathematical structure and
>> quantitative functor between those mathematical structure and numbers
>> that we can measure in some communicable ways.
>
> No physical theory needs to presuppose numbers as
> having an existence of their own. Formalists
> can do physics.


But they cannot interpret their theory. Now, you can be formalist with 
respect to the lobian interview, but then you should try to understand 
formally the theory (at least).
But frankly I have no clues about how a formalist can apply any theory 
without accepting some interpretation of the formula in the theory.

Bruno

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


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