> Date: Sat, 13 Feb 2010 10:48:28 -0800
> From: jackmal...@yahoo.com
> Subject: Re: problem of size '10
> To: everything-list@googlegroups.com
> --- On Fri, 2/12/10, Bruno Marchal <marc...@ulb.ac.be> wrote:
> > Jack Mallah wrote:
> > --- On Thu, 2/11/10, Bruno Marchal <marc...@ulb.ac.be>
> > > > MGA is more general (and older).
> > > > The only way to escape the conclusion would be to attribute 
> > > > consciousness to a movie of a computation
> > >
> > > That's not true.  For partial replacement scenarios, where part of a 
> > > brain has counterfactuals and the rest doesn't, see my partial brain 
> > > paper: http://cogprints.org/6321/
> >
> > It is not a question of true or false, but of presenting a valid or non 
> > valid deduction.
> What is false is your statement that "The only way to escape the conclusion 
> would be to attribute consciousness to a movie of a computation".  So your 
> argument is not valid.
> > I don't see anything in your comment or links which prevents the 
> > conclusions of being reached from the assumptions. If you think so, tell me 
> > at which step, and provide a justification.
> Bruno, I don't intend to be drawn into a detailed discussion of your 
> arguments at this time.  The key idea though is that a movie could replace a 
> computer brain.  The strongest argument for that is that you could gradually 
> replace the components of the computer (which have the standard 
> counterfactual (if-then) functioning) with components that only play out a 
> pre-recorded script or which behave correctly by luck.  You could then invoke 
> the 'fading qualia' argument (qualia could plausibly not vanish either 
> suddenly or by gradually fading as the replacement proceeds) to argue that 
> this makes no difference to the consciousness.  My partial brain paper shows 
> that the 'fading qualia' argument is invalid.

Hi Jack, to me the idea that counterfactuals would be essential to defining 
what counts as an "implementation" has always seemed counterintuitive for 
reasons separate from the Olympia or movie-graph argument. The 
thought-experiment I'd like to consider is one where some device is implanted 
in my brain that passively monitors the activity of a large group of neurons, 
and only if it finds them firing in some precise prespecified sequence does it 
activate and stimulate my brain in some way, causing a change in brain 
activity; otherwise it remains causally inert (I suppose because of the 
butterfly effect, the mere presence of the device would eventually affect my 
brain activity, but we can imagine replacing the device with a subroutine in a 
deterministic program simulating my brain in a deterministic virtual 
environment, with the subroutine only being activated and influencing the 
simulation if certain simulated neurons fire in a precise sequence). According 
to the counterfactual definition of implementations, would the mere presence of 
this device change my qualia from what they'd be if it wasn't present, even if 
the neurons required to activate it never actually fire in the correct sequence 
and the device remains completely inert? That would seem to divorce qualia from 
behavior in a pretty significant way...
If you have time, perhaps you could take a look at my post at 
where I discussed a vague idea for how one might define isomorphic "causal 
structures" that could be used to address the implementation problem, in a way 
that wouldn't depend on counterfactuals at all (there was some additional 
discussion in the followup posts on that thread, linked at the bottom of that 
mail-archive.com page). The basic idea was to treat the physical world as a 
formal axiomatic system, the axioms being laws of physics and initial 
conditions, the theorems being statements about physical events at later points 
in spacetime; then "causal structure" could be defined in terms of the patterns 
of logical relations between theorems, like "given the axioms along with 
theorems A and B, we can derive theorem C". Since all theorems concern events 
that actually did happen, counterfactuals would not be involved, but we could 
still perhaps avoid the type of problem Chalmers discussed where a rock can be 
viewed as implementing any possible computation. If you do have time to look 
over the idea and you see some obvious problems with it, let me know...

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