MGA 3
It is the last MGA !
I realize MGA is complete, as I thought it was, but I was doubting
this recently. We don't need to refer to Maudlin, and MGA 4 is not
necessary.
Maudlin 1989 is an independent argument of the 1988 Toulouse argument
(which I present here).
Note that Maudlin's very interesting "Olympization technic" can be
used to defeat a wrong form of MGA 3, that is, a wrong argument for
the assertion that the movie cannot be conscious. (the argument that
the movie lacks the counterfactual). Below are hopefully correct (if
not very simple) argument. ( I use Maudlin sometimes when people gives
this non correct form of MGA 3, and this is probably what makes me
think Maudlin has to be used, at some point).
MGA 1 shows that Lucky Alice is conscious, and MGA 2 shows that the
"luckiness" feature of the MGA 1 experiment was a red herring. We can
construct, from MEC+COMP, an home made lucky rays generator, and use
it at will. If we accept both digital mechanism, in particular
Dennet's principle that neurons have no intelligence, still less
prescience, and this *together with* the supervenience principle; we
have to accept that Alice conscious dream experience supervenes on the
projection of her brain activity movie.
Let us show now that Alice consciousness *cannot* supervene on that
*physical* movie projection.
I propose two (deductive) arguments.
1)
Mechanism implies the following tautological functionalist principle:
if, for some range of activity, a system does what it is supposed to
do, and this before and after a change is made in its constitution,
then the change does not change what the system is supposed to do, for
that range of activity.
Example:
- A car is supposed to broken but only if the driver is faster than 90
miles/h. Pepe Pepito NEVER drives faster than 80 miles/h. Then the car
is supposed to do what she is supposed to do, with respect of its
range of activity defined by Pepe Pepito.
- Claude bought a 1000 thousand processors computer. One day he
realized that he used only 990 processors, for his type of activity,
so he decided to get rid of those 10 useless processors. And indeed
the machine will satisfy Claude ever.
- Alice has (again) a math exam. Theoreticians have correctly predict
that in this special circumstance, she will never use neurons X, Y and
Z. Now Alice go (again, again) to this exam in the same condition,
but with the neurons X, Y, Z removed. Again, not only will she behaved
like if she succeed her exam, but her consciousness, with both MEC
*and* MAT still continue.
The idea is that if something is not useful, for an active process to
go on, for some range of activity, then you can remove it, for that
range of activity.
OK?
Now, consider the projection of the movie of the activity of Alice's
brain, "the movie graph".
Is it necessary that someone look at that movie? Certainly not. No
more than it is needed that someone is look at your reconstitution in
Moscow for you to be conscious in Moscow after a teleportation. All
right? (with MEC assumed of course).
Is it necessary to have a screen? Well, the range of activity here is
just one dynamical description of one computation. Suppose we make a
hole in the screen. What goes in and out of that hole is exactly the
same, with the hole and without the hole. For that unique activity,
the hole in the screen is functionally equivalent to the subgraph
which the hole removed. Clearly we can make a hole as large as the
screen, so no need for a screen.
But this reasoning goes through if we make the hole in the film
itself. Reconsider the image on the screen: with a hole in the film
itself, you get a "hole" in the movie, but everything which enters and
go out of the hole remains the same, for that (unique) range of
activity. The "hole" has trivially the same functionality than the
subgraph functionality whose special behavior was described by the
film. And this is true for any subparts, so we can remove the entire
film itself.
Does Alice's dream supervene (in real time and space) on the
projection of the empty movie?
Remark.
1° Of course, this argument can be sum up by saying that the movie
lacks causality between its parts so that it cannot really be said
that it computes any thing, at least physically. The movie is just an
ordered record of computational states. This is neither a physical
computation, nor an (immaterial) computation where the steps follows
relatively to some universal machine. It is just a description of a
computation, already existing in the Universal Deployment.
2° Note this: If we take into consideration the relative destiny of
Alice, and supposing one day her brain broke down completely, she has
more chance to survive through "holes in the screen" than to the
"holes in the film". The film contains the relevant information to
reconstitute Alice from her brain description, contained on this high
resolution film. Keeping comp, and abandoning the physical
supervenience thesis, means that we do no more associate
consciousness, neither on the movie, NOR on the brain special activity
in a computation, but to the computation itself directly. A brain, and
even a film, will "only" be a way to make bigger the probability
for a consciousness to manifest itself relatively to a "probable"
universal computational history.
Strictly speaking, running the movie dimimish Alice chance to have her
conscious experience (life) continue, at least relatively to you,
because of the many scratches the projector makes on the pellicle,
which remove relevant information for a safe reconstitution later
(again relatively to you).
2)
I give now what is perhaps a simpler argument
A projection of a movie is a relative phenomenon. On the planet 247a,
nearby in the galaxy, they don't have screen. The film pellicle is as
big as a screen, and they make the film passing behind a stroboscope
at the right frequency in front of the public. But on planet 247b,
movies are only for travellers! They dress their film, as big as those
on planet 247a, in their countries all along their train rails with a
lamp besides each frames, which is nice because from the train,
through its speed, you get the usual 24 frames per second. But we
already accepted that such movie does not need to be observed, the
train can be empty of people. Well the train does not play any role,
and what remains is the static film with a lamp behind each frame. Are
the lamps really necessaries? Of course not, all right? So now we are
obliged to accept that the consciousness of Alice during the
projection of the movie supervenes of something completely inert in
time and space. This contradicts the *physical* supervenience thesis.
Exercises.
a) Someone could propose an alternate argument that a movie does not
compute (and so consciousness does supervene on it) by alluding to the
lack of causality in the movie: the movie does not handle the
counterfactual existing implicitly in computations (physical or not).
Use Maudlin's Olympization technic to refute that argument.
b) Make fun by using a non dreaming Alice. Shows that the movie (film
or screen) graph border is needed to get the accidental zombies (the
puppet).
And then the "important" exercise (the original goal).
c) Eliminate the hypothesis "there is a concrete deployment" in the
seventh step of the UDA. Use UDA(1...7) to define properly the
computationalist supervenience thesis. Hint: reread the remarks above.
Have a good day.
Bruno
http://iridia.ulb.ac.be/~marchal/
http://iridia.ulb.ac.be/~marchal/
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Received on Wed Nov 26 2008 - 04:09:27 PST