Quentin Anciaux wrote:
2010/1/12 Brent Meeker <meeke...@dslextreme.com
<mailto:meeke...@dslextreme.com>>
Quentin Anciaux wrote:
2010/1/12 Brent Meeker <meeke...@dslextreme.com
<mailto:meeke...@dslextreme.com>
<mailto:meeke...@dslextreme.com
<mailto:meeke...@dslextreme.com>>>
Stathis Papaioannou wrote:
2010/1/12 Brent Meeker <meeke...@dslextreme.com
<mailto:meeke...@dslextreme.com>
<mailto:meeke...@dslextreme.com
<mailto:meeke...@dslextreme.com>>>:
I know. I'm trying to see what exactly is being
assumed
about the
computation being "the same". Is it the same Platonic
algorithm? Is it
one that has the same steps as described in
FORTRAN, but
not those in LISP?
Is it just one that has the same input-output? I
think
these are questions
that have been bypassed in the "yes doctor" scenario.
Saying "yes" to the
doctor seems unproblematic when you think of
replacing a
few neurons with
artificial ones - all you care about is the
input-output.
But then when you
jump to replacing a whole brain maybe you care
about the
FORTRAN/LISP
differences. Yet on this list there seems to be an
assumption that you can
just jump to the Platonic algorithm or even a Platonic
computation that's
independent of the algorithm. Bruno pushes all this
aside by referring to
"at the appropriate level" and by doing all possible
algorithms. But I'm
more interested in the question of what would I
have to do
to make a
conscious AI. Also, it is the assumption of a Platonic
computation that
allows one to slice it discretely into OMs.
Start by replacing neurons with artificial neurons
which are
driven by
a computer program and whose defining characteristic is
that
they copy
the I/O behaviour of biological neurons. The program has to
model the
internal workings of a neuron down to a certain level.
It may
be that
the position and configuration of every molecule needs
to be
modelled,
or it may be that shortcuts such as a single parameter
for the
permeability of ion channels in the cell membrane make no
difference
to the final result. In any case, there are many
possible programs
even if the same physical model of a neuron is used,
and the same
basic program can be written in any language and
implemented
on any
computer: all that matters is that the artificial
neuron works
properly. (As an aside, we don't need to worry about
whether these
artificial neurons are zombies, since that would lead
to absurd
conclusions about the nature of consciousness.) From the
single neuron
we can progress to replacing the whole brain, the end
result
being a
computer program interacting with the outside world through
sensors
and effectors. The program can be implemented in any
way - any
language, any hardware - and the consciousness of the
subject will
remain the same as long as the brain behaviour remains
the same.
You're asserting that neuron I/O replication is the
"appropriate
level" to make "brain behavior" the same; and I tend to
agree that
would be sufficient (though perhaps not necessary). But that's
preserving a particular algorithm; one more specific than the
Platonic computation of its equivalence class. I suppose a
Turing
machine could perform the same computation, but it would
perform
it very differently. And I wonder how the Turing machine would
manage perception. The organs of perception would have their
responses digitized into bit strings and these would be
written to
the TM on different tapes? I think this illustrates my point
that, while preservation of consciousness under the digital
neuron
substitution seems plausible, there is still another leap in
substituting an abstract computation for the digital neurons.
Also, such an AI brain would not permit slicing the
computations
into arbitrarily short time periods because there is
communication
time involved and neurons run asynchronously.
Yes you can, freeze the computation, dump memory... then load
memory back, and defreeze. If the time inside the computation
is an internal feature (a counter inside the program), the AI
associated to the computation cannot notice anything if on the
other hand the time inside of the computation is an input
parameter from some external then it can notice... but I
always can englobe the whole thing and feed that external time
from another program or whatever.
That assumes that the AI brain is running synchronously, i.e. at a
clock rate small compared to c/R where R is the radius of the
brain. But I think the real brain runs asynchronously, so if the
AI brain must do the simulation at a lower level to take account
of transmission times, etc. and run at a much higher clock rate
than do neurons. But is it then still "the same" computation?
The fact that you can disrupt a computation and restart it
with some different parameters doesn't mean you can't restart
it with *exactly* the same parameters as when you froze it.
That's arbitrarily excluding the physical steps in "freezing" and
"starting" a computation, as though you can pick out the "real"
computation as separate from the physical processes. Which is the
same as assuming that consciousness attaches to the Platonic
"real" computation and those extra physical steps somehow don't
count as "computations".
But it is the same... When I write a program in say java... that's not
my "program" that is run on the machine, it is a translation in the
target machine language. Yet it is the same, that's what we use UTM for.
Also the restarted computation has no knowledge at all of having been
freezed and restarted in the first place.
Well maybe I'm confused about this, but you're talking about a program
that has the same input/output and therefore all the processes after the
input and before the program halts are irrelevant. You're saying it's
"the same" if the same inputs halt with the same outputs - which is the
abstract Turing machine or Platonic meaning of "the computation". I
don't see that as being the same as attaching consciousness to brain
processes which don't halt? How are you mapping the Turing computation
to the brain process? If you replace each neuron with a Turing machine
that reproduces the same input/output, I can understand the mapping.
But then you reproduce that collection of interacting Turing machines
with a single, super-Turing machine which includes some simulation of
the local environment too. Because the neuron level Turing machines ran
asynchronously, the super-Turing machine has to include a lot of
additional computation to keep track of the signal passing. Yet we are
to bet that it instantiates the same stream of consciousness because -
exactly why?...because it will halt on the same outputs for the same inputs?
Brent
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