# Re: Movie graph and computational supervenience

```On 29 Jan 2009, at 20:42, Quentin Anciaux wrote:
```
```
>
>
> Why would the movie graph rule out a notion of *computational*
> supervenience. We can keep comp and abandon materialism. We can
> still say yes to the digitalist doctor, by betting on our more
> probable relative computational histories.
>
> Because here there was no "physical" graph at the start... it's just
> a program and we replace various subpart of it which instead of
> computing make a lookup. Now frow what you are saying I should
> understand that the program is a "description" of a computation, not
> a computation

Not really.
A program is a finite piece of information capable of making computing
some universal machine. The computation is the activity (abstract or
physical, etc.) of that universal machine.

> and "consciousness" supervene on computation but not description of
> computation ? Then I'm lost about what is a computation ?

Here we met a typical difficulty, a bit like showing the moon to a
cat. The cat looks only to the finger. The difficulty is illustrated
by famous paintings of Magritte: "ceci n'est pas une pipe" (a drawing
of a pipe, with the mention: this is not a pipe).

Except that this difficulty is  more severe in our context.

> I would thing a computation is the act of "running" the program,
> execute each step and modifying the internal state.

Well it is exactly that, except that you are ambiguous if the act has
to be physically implemented or could be realized into purely numeric
relations.

But it is exactly what you say: so a computation will usually be
described by a logical sequence of "states": A, B, C, D, ...

And what I am saying is that comp makes consciousness supervening on
A, B, C, D, ... (a computation), but that consciousness does not
supervene on a description (in some language) of the computation "A,
B, C, D,  ...".
It is really the difference between A, B, C, D, ..., and  "A; B, C,
D, ..."

Even in the abstract we have to distinguish something like a number, a
machine, a theory, a proof, a computation, from their abstract (but
coded) descriptions.

Later I will probably describe a computation by a number (PA handles
only numbers). Consciousness does not supervene on such a number. It
will appear that if PA (or RA) proves the existence of that numbers
together with an account that it represents
a computation, such a proof will be truly (but not necessarily
provably) equivalent to a computation.

Of course this is a bit subtle, and for being clear we have to be
technical and provide definitions. I will say more in the seven step.
It is subtle because computations themselves uses descriptions of
things, so confusions can grow, and one confusion on one level extends
on all levels!

Your definition of computation is correct. In platonia, a computation
is NOT automatically equivalent to a *description* of a computation.
Why would the finger and the moon collapse in platonia?

>
>
> I'm talking about a modified version of the movie graph where
> instead of starting with a conscious physical gates machine, I start
> with a conscious program and transform it accordingly (broken gates
> + projection of the film in the movie graph, in my case, stub
> subpart which do a lookup instead of computing the value)
>
>
> The absurdity with the movie graph is that it shows that associating
> consciousness to the *physical* implementation leads us to attribute
> consciousness to a description of a computation, and that is
> ridiculous.
> (Well at least, once you understand what is a (mathematical)
> computation, I think many are confused here, I will come back on
> this).
> Computations and descriptions of computation are related, but
> differs and are not of the same type, nor level. It is hard to be
> clearer without going through computer science.  Probably more in my
> next post to Kim on the Seventh Step.
>
> I am not really sure I get your "ruling out all kinds of
> supervenience".
>
> Because from what I understand (which is surely wrong) it's absurd
> at all... (supervenience of consciousness) :

But if you say yes to the doctor, you do accept that your (local and
relative) consciousness will or should supervenes on something. You
would not say yes to a doctor who proposes the simple brain ablation
experience.

>
>
> from wikipedia:
> A supervenes on a set of properties B, if and only if any two
> objects x and y which share all properties in B (are "B-
> indiscernible") must also share all properties in A (are "A-
> indiscernible").

Very good definition. So a naturalist will say that some consciousness
(A) supervenes on some dynamic of a brain (B), if any dynamics x and y
sharing the dynamic of the brain (B), will share the same
consciousness (A).
Now if we assume comp, those dynamics are turing emulable, and this,
by UDA, makes consciousness (of one person) supervening on "sheaf of
possible digital dynamic (computations) . It imposes constraints in
the space of possible dynamic and constraints about what self-
referential entities can bet about their most probable digital dynamics.

Tell me if this has helped. Your questioning is very relevant.

Bruno

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

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