meekerdb wrote:
On 5/15/2015 6:18 PM, Bruce Kellett wrote:
meekerdb wrote:
On 5/15/2015 4:40 PM, Bruce Kellett wrote:
meekerdb wrote:
On 5/14/2015 7:24 PM, Bruce Kellett wrote:
LizR wrote:
On 15 May 2015 at 06:34, meekerdb <meeke...@verizon.net
<mailto:meeke...@verizon.net>> wrote:
I'm trying to understand what "counterfactual correctness"
means in
the physical thought experiments.
You and me both.
Yes. When you think about it, 'counterfactual' means that the
antecedent is false. So Bruno's referring to the branching 'if A
then B else C' construction of a program is not really a
counterfactual at all, since to be a counterfactual A *must* be
false. So the counterfactual construction is 'A then C', where A
happens to be false.
The role of this in consciousness escapes me too.
It comes in at the very beginning of his argument, but it's never
made explicit. In the beginning when one is asked to accept a
digital prosthesis for a brain part, Bruno says almost everyone
agrees that consciousness is realized by a certain class of
computations. The alternative, as suggested by Searle for example,
that consciousness depends not only of the activity of the brain
but also what the physical material is, seems like invoking magic.
So we agree that consciousness depends on the program that's
running, not the hardware it's running on. And implicit in this is
that this program implements intelligence, the ability to respond
differently to different externals signals/environment. Bruno says
that's what is meant by "computation", but whether that's entailed
by the word or not seems like a semantic quibble. Whatever you
call it, it's implicit in the idea of digital brain prosthesis and
in the idea of strong AI that the program instantiating
consciousness must be able to respond differently to different inputs.
But it doesn't have respond differently to every different input or
to all logically possible inputs. It only needs to be able to
respond to inputs within some range as might occur in its
environment - whether that environment is a whole world or just the
other parts of the brain. So the digital prosthesis needs to do
this with that same functionality over the same domain as the brain
parts it replaced. In which case it is "counterfactually correct".
Right? It's a concept relative to a limited domain.
That is probably right. But that just means that the prosthesis is
functionally equivalent over the required domain. To call this
'counterfactual correctness' seems to me to be just confused.
What makes the consciousness, in Bruno's view, is that it's the right
kind of program being run - which seems fairly uncontroversial. And
part of being the right kind is that it is "counterfactually correct"
= "functionally equivalent at the software level". Of course this
also means it correctly interfaces physically with the rest of the
world of which it is conscious. But Bruno minimizes this by two
moves. First, he considers the brain as dreaming so it is not
interacting via perceptions. I objected to this as missing the
essential fact that the processes in the brain refer to perceptions
and other concepts learned in its waking state and this is what gives
them meaning. Second, Bruno notes that one can just expand the
digital prosthesis to include a digital artificial world, including
even a simulation of a whole universe. To which my attitude is that
this makes the concept of "prosthesis" and "artificial" moot.
I don't think you would consider just *any* piece of software running
to be conscious and I do think you would consider some, sufficiently
intelligent behaving software, plus perhaps certain I/O, to be
conscious. So what would be the crucial difference between these two
software packages? I'd say having the ability to produce intelligent
looking responses to a large range of inputs would be a minimum.
Quite probably. But the argument was made that the detailed recording
of the sequence of brain states of a conscious person could not be
conscious because it was not counterfactually correct. This charge has
always seemed to me to be misguided, since the recording does not
pretend to be functionally equivalent to the original in all
circumstances -- just in the particular circumstance in which the
recording was made. It has never been proposed that the film could be
used as a prosthesis for all situations. So this argument against the
replayed recording recreating the original conscious moments must fail
-- on the basis of total irrelevance.
But you could turn this around and pick some arbitrary
sequence/recording and say, "Well it would be the right program to be
conscious in SOME circumstance, therefore it's conscious."
I think it goes without saying that it is a recording of brain activity
of a conscious person -- not a film of your dog chasing a ball. We have
to assume a modicum of common sense.
Bruce
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