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 <[email protected]
<mailto:[email protected]>> 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.
Bruce
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