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.
Brent
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