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.
Bruce
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