# Re: Movie Graph Argument: A Refutation

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On 26 Dec 2011, at 05:47, Joseph Knight wrote:```
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On Sat, Dec 24, 2011 at 9:05 AM, Bruno Marchal <marc...@ulb.ac.be> wrote:
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On 23 Dec 2011, at 20:16, Joseph Knight wrote:
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The same problem arises in Part 2. Bruno claims that we are forced to accept that Alice’s consciousness supervenes on the film.
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No. On the projection of the pellicle on the Boolean graph, and then on the Boolean graph missing part. The idea is that we built again the right physical activity, with the projection of the film playing the role of the cosmic rays.
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What is a pellicle? (Sorry) I understand this part, however. My objections arise later.
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A film. (But in french "film" is for cinema (movie?)).

OK, there was no confusion.
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OK.

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but (film + optical graph) is certainly changed, and Alice’s dream turns out differently (if it occurs at all).
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With comp + sup-phys, it can't.

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Why? If we assume sup+phys, then some changes in the physical system on which the dream supervenes certainly will lead to changes in the dream.
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I don't think so. Remember that we suppose comp (and sup-phys). So we already agree that we can change the physical implementation if it runs the computation at the correct level. So, we can change the physical implementation as we wish, below the substitution level without changing the first person private consciousness.
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I think I wasn't clear here. I didn't mean changes in the particular physical system consciousness is supervening on -- of course by comp that doesn't matter. I meant that, assuming sup-phys on physical system X, there must exist some changes in X which lead to changes in consciousness.
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OK.

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Bruno isolates the film and thus reaches his apparent contradictions. But this is not a permissible move.
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I think that the term "film" could have different meaning in french and english. But the film here means the projection of the pellicle on the glass/crystal medium. This one is never broken. It is a process which takes time, and occur in some place.
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Not only is the definition of supervenience violated, but his principle of irrelevant subparts is violated as well – for the optical graph is not irrelevant for the execution of Alice’s consciousness.
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Of course, but once we put away the nodes, the physical activity corresponding to the computation are not changed. The optical graph becomes irrelevant for the physical activity on which Alice's consciousness is supposed to supervene, by comp+sup-phys.
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This is where my problem lies. Of course the physical activity of the system is changed when you (invalidly) remove the optical graph from the system. It is far from irrelevant. For example, what mechanism causes the light to triggers the lasers? There must be some "internal" mechanisms at work as well. The nodes aren't "connected" to one another, but it matters whether or not the recording is being projected on an optical graph, vs. a concrete wall, vs. movie screen....
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Why? The relevant physical activity is the same.
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Obviously I agree with you (the projection of the film does not instantiate consciousness). The point is that if comp and sup-phys are maintained, and if 323 is correct, then there is nothing different from projecting the film on the glass crystal with the boolean laser graph removed and a wall.
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I have no problem with 323. My argument is that consciousness never supervenes on the film/movie/recording.
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I agree with that. If only because there are no more any computation done "in time and space" (the original abstract computation does not disappear, of course, so with comp, we will have to attach consciousness to it, and not to its particular "concrete implementation".
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So there is something different between projecting the film on the glass crystal, and the wall. The relevant physical activity, in the two cases (glass/crystal vs wall), is not the same. In the first case (and not the second) the light interacts with the crystal medium and triggers the lasers. How can you argue that this interaction is irrelevant and can be removed?
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Because that special activity has nothing to do with the original computation. If it were, I could not have said yes to the doctor at the start. Once the boolean graph is remove, we just get a special weird screen. And the absurdity is still there: there are no computation done when we project on that weird sort of screen.
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Let me restate my concern: Consciousness supervenes on the optical graph+the recording, even when the nodes are completely disconnected. It is true that "most of the work" is being done by the recording, but not all of the work. The optical graph still matters, and the "physical activity" of the system is not solely provided by the recording, as it still depends on how the projected light interacts (physically) with the glass/crystal surface.
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But this is no more relevant in term of the computation, which is supposed to be a copy of the brain processing at the right level or below.
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There is a point in the argument at which you ignore the glass/ crystal system and focus solely on the movie/recording, claiming that Alice's consciousness supervenes on the movie/recording. But this is false. At no point does Alice's consciousness supervene on the recording, not even when the nodes are completely disconnected.
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Yes. That's why it is a reductio ad absurdum.

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Its a reductio ad absurdum only if you artificially ignore the interaction between the projected light and the crystal medium and lasers. Because consciousness supervenes on crystal/glass/nodes +film, it is not meaningful to make this move. Consciousness changes do not imply film changes (even though the converse may well be true). You have isolated a subsystem from the machine, mistaken this subsystem for being sufficient for consciousness to supervene on -- little wonder an absurd conclusion follows!
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I could because all this is supposed to be done below the substitution level.
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I am trying to think of an analogy to another system which would make my argument clearer (and in the process learning how tricky the concept of supervenience can be).
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Actually, I do the same. I search a system where I can make it clearer why the idiosyncrasies of the movie-graph are simpler to evacuate. But in the present case, it seems rather obvious to me that the absurdity is already there, before replacing the glass+smoke by a usual screen. There is already no more computations, we can already use the stroboscopic argument to make that absurd.
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Bruno

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

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