On 01 Apr 2012, at 22:13, meekerdb wrote:

On 4/1/2012 6:33 AM, David Nyman wrote:

Bruno, when you talk about the doctor offering one a replacement brain
you usually describe the substitute as digital, although I think you
have sometimes just said that it is artificial.  My recent remarks
about "game physics" got me thinking about this distinction, if indeed
there is one.

Suppose Dick's friend Harry, having been previously diagnosed with an
incurable brain cancer, has had an artificial brain installed. The
doctor tells Dick that he has replaced Harry's brain with a (very
sophisticated!) battery-driven clockwork substitute. Harry tells Dick
that the replacement has been entirely successful: "After the
operation I felt a little woozy at first, but I feel great now.  My
memory is excellent - if anything better than before - and my
appreciation of the finer things in life is as vivid as ever."  Dick
is a bit sceptical at first (his faith in clockwork has been
prejudiced by a rather unreliable fake Rolex he bought in Hong Kong)
but over a period of several months of careful observation he finds he
can't distinguish any difference whatsoever between Harry's new
clockwork personality and his former self.  Their friendship is

This turns out to be just as well, because - horror of horrors - Dick
is shortly afterwards also diagnosed with a terminal brain condition.
Should he now be willing to submit to the same procedure as Harry? He
is still a little sceptical of clockwork, but the evidence of Harry's
successful transformation is very difficult to discount, and the
doctor shows him several other "before and after" videos with equally
convincing outcomes. The artificial brains may be clockwork, but the
doctor assures him it is clockwork of unprecedented  sophistication
and precision, unheard of even in the hallowed halls of Swiss
horology. Dick has stumbled across the Everything List, and is rather
persuaded by the computational theory of mind. Trouble is, the doctor
is not of this persuasion.  He tells Dick that the goal of the
operation is only to substitute a clockwork analogue for the
electro-chemical mechanisms of his organic brain, and that on this
basis Dick can confidently expect that the same inputs will reliably
elicit the same responses as before.  Hearing this, Dick is now
worried that, however successful the replacement of Harry's brain has
been behaviourally, his friend is now essentially a mindless clockwork

Since he certainly doesn't want to suffer such an indignity, should he
say no to the doctor?  The question that troubles Dick is whether,
assuming comp, he should accept a genuinely
behaviourally-indistinguishable body, irrespective of its brain being
organic or clockwork, as an equivalent "avatar" according to the rules
of the comp game-physics.  If so, Dick should have no reason not to
accept a behaviourally-indistinguishable, clockwork-equipped body as
enabling his continued manifestation relative to the familiar
environments to which he has become so emotionally attached.  Time is
short, and he must act.  What should he do?


Go for it. The important thing is the computational interaction with the world (including one's own body). If the world is analog fine. Bruno thinks a digital substitution will work because a digital computation can emulate an analog to any specified precision

Only the analogs which does not rely on infinite information. If r is a non computable real number, e^iH(r,t) can be a solution to the SWE, and yet will be an analog non Turing emulable process. Of course it is doubtful that a brain relies on such quantum non computable process.

- but they are not identical. If the world is digital the converse works too, the analog clockwork can emulate the digital.

If the word is digital, analog computation would not exist. Of course the laws of big numbers would still justified the term analog for very complex computations, but it would be an approximation.

Although I think that upsets some of Bruno's inferences that depend on provability.

That "upsets" me already from the UDA. If I am digital (= "I survive with a digital generalized brain"), then there is a continuum of computation going through my state, due to the local emulation of the computation with oracles made by the UD (indeed all the iterated duplications are emulated by the UD), so a priori the physical reality explanation has to be retrieved from an 1-indeterminacy bearing on a continuum domain.

The "matter hypostases" variant of provability only seems to confirm this.



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