On 5 March 2010 06:43, Jack Mallah <jackmal...@yahoo.com> wrote:

>> similarly in your paper where you consider a gradual removal of brain 
>> tissue. It would have to be very specific surgery to produce the sort of 
>> delusional state you describe.
> I'm not sure if you overlooked it but the key condition in my paper is that 
> the inputs to the remaining brain are identical to what they would have been 
> if the whole brain were present.  Thus, the neural activity in the partial 
> brain is by definition identical to what would have occured in the 
> corresponding part of a whole brain.  It is of course grossly implausible 
> that this could be done in practice for a real biological brain (for one 
> thing, you'd pretty much have to know in advance the microscopic details of 
> everything that would have gone on in the removed part of the brain, or else 
> guess and get incredibly lucky), but it presents no difficulties in priciple 
> for a digital simulation, and in any case is a thought experiment.

If the inputs to the remaining brain tissue are the same as they would
have been normally then effectively you have replaced the missing
parts with a magical processor, and I would say that the thought
experiment shows that the consciousness must be replicated in this
magical processor. Functionalism is sometimes used interchangeably
with computationalism, but computationalism is only a subset of
functionalism. It could be, for example, that the brain is not
computable because it uses exotic physics of the sort postulated by
Penrose. We would then fail in our efforts to make a computer that
behaves like a human. However, we could succeed if we used
non-computational components. If we replace a neuron with a demon that
reproduces its I/O behaviour, the behaviour of the whole brain will be
unchanged and its consciousness will also be unchanged. Functionalism
is saved, even if computationalism is lost.

The main problem I have with "fading qualia" is that it would lead to
the possibility of partial zombies. If partial zombies are possible,
then I might be a partial zombie now and not know it. I may, for
example, have zombie vision: I believe I can see, I can correctly
describe everything I look at, but in fact I am completely lacking in
visual perception. What am I missing out on? I am apparently not
missing out on anything. The zombie vision is just as good, in every
objective and subjective sense, as normal vision. So the objection to
the fading qualia is either that the qualia won't fade, or if they do
fade they will be replaced by zombie qualia that are indistinguishable
from normal qualia and we may as well call normal qualia.

Stathis Papaioannou

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