Re: A calculus of personal identity

From: Bruno Marchal <>
Date: Mon, 26 Jun 2006 11:24:18 +0200

Le 25-juin-06, à 10:51, Stathis Papaioannou a écrit :

>> From a logical point of view it is consistent (possible) that the one
>> reconstituted is a zombie (although this would contradict comp or the
>> choice of the level).
> It depends on what we mean by "all the appropriate mental and physical
> attributes". If the reconstituted person is a zombie then he is
> certainly lacking some mental attributes that the original had,
> assuming the original was not a zombie.

Indeed: he loss the consciousness!

> Of course, it is not possible for a third person observer to be
> certain about first person mental states, and this would apply to our
> teleportee: he may feel as if he is the same person as he was prior to
> the procedure, but he might be wrong.

If he is a zombie, by definition he feels nothing.

> The flaw in this argument is that the same considerations hold if he
> had travelled by train: he may look and feel like the same person,
> have all the appropriate memories, and so on, but how does he know
> that the original didn't die during the journey, to be replaced by a
> copy as would have happened had he teleported?

Here I agree and see what you mean. That is why those saying "yes" to
the doctor eventually should understand we do die at each instant. Like
we do "split" or differentiate at each instant without any means to
know that directly.

> In a sense, this is just what did happen, since over minutes to hours
> most of the matter comprising neural synapses is replaced, while over
> months most of the matter in a human body is replaced.

OK. Note that a non-computationalist can invoke some continuity of
replacement. Such argument are red herring once we assume comp.

> If there is some sense in which a person's identity might be lost
> despite his physical and mental attributes being apparently preserved
> (and I'm not sure the idea is even coherent), there is no reason for
> nature to waste effort evolving and maintaining such an
> identity-conservation system, because it cannot make any difference to
> behaviour.

I would agree if I was believing in Nature. As a scientist I am neutral
about the existence of nature, but assuming comp "Nature", like
"matter" should not be reified.

>> Comp itself cannot be proved but what can be proved is that IF comp is
>> correct then comp cannot be proved, necessarily. So we have, somehow,
>> to be open to non-comp beliefs.
>> Put in another way: if you survive when saying YES to the doctor, you
>> have to respect those who say NO to the doctor (unless you have bad
>> intentions of course or are ignorant).
> The falseness of comp (or functionalism) does not necessarily mean
> duplication would be a death sentence.

You are right but the reverse is true: if duplication (at any level) is
a death sentence, then comp is wrong.
But you a right, for example we could survive duplication because God
is so good and so clever as being able to duplicate our non-comp-soul
and link it to the genuine digital brain copies ....

> If our consciousness is dependent on the activity of tiny black holes
> in the microtubules, or whatever, then we might be able to survive
> duplication if our new brain had the right sort of tiny black holes in
> the microtubules. The test is that the duplicate have subjective
> experiences sufficiently close to those of the original: if that is
> the case, then I would say by definition the person has survived.

All right, but this is never third person verifiable. To test comp BY
saying yes to a doctor and getting an artificial digital brain is akin
to "quantum suicide" or "comp suicide". The first person can get the
correct (assuming comp and the rightness of the level choice) *feeling*
of having survive, but she will never be able to communicate this
feeling to another.

>> Parfit has not see this, and that is why he dares to qualify (a bit
>> provocatively I would say) his identity theory as a reductionist
>> theory, or "the reductionist theory". With comp (when made explicit)
>> Parfit's theory is mainly correct except on two points:
>> 1) What I have just said: the theory is not reductionist---It is the
>> contrary: it provides (by diagonalizations!) many vaccine against many
>> form of reductionism. After dinner ;) I could even go as far as to say
>> it gives a path toward that Unconceivable Freedom described by some
>> mystic like Vimalakirti!
>> 2) We are type, not token. There is no physical token. (with comp).
>> Parfit thinks we are token. I have not the Parfit under the hand, I
>> will give you the pages later. I don't think there are any
>> mathematical
>> token either. It looks like Parfit makes us token for avoiding
>> immortality at the start.
> You may be referring to chapter 99 of "Reasons and Persons". A "token"
> is a particular instantiation of a person, while a "type" is the set
> of related instantiations (these terms are actually attributed to the
> philosopher Bernard Williams). As I read him, Parfit says that we are
> each token, but the significance we attach to our lives and those of
> others we care about must be attached to a type rather than a
> particular token. Thus, in destructive teleportation, a token is
> destroyed, but the type survives.

I think this makes Parfit non coherent. If I am a token, and if only
the type survive, I don't survive.

>> To sum up, Hal Finney seemed to me coherent, giving that in its recent
>> post he admits questioning comp. It is less clear for me how he can
>> still use Kolmogorov complexity (a computer science notion), but
>> still,
>> logically that could make sense, perhaps through some Powerful Oracle
>> resource (actual infinity of highly uncomputable information). I don't
>> know. Hal?
> Hal promised to explain how a person might not survive destructive
> teleportation despite being apparently subjectively and objectively
> unchanged, and I look forward to this.

Again, if there is no subjective change at all I would say the survival
is obvious by definition. But assuming some strong form of
non-computationalism, we can *conceive* that the subjectivity belongs
to someone else after the reconstitution. My point here is that comp is
not positively testable, even for oneself (someone reconstituted person
could say: "I have survived, I have survived, I have survived, ..." and
then repeat this forever because its hypocampus (which handles the
short/long term memory interface) would have been destroyed in the
process. Any possible "agnosology" I mean (brain diseases which entail
the lack of consciousness of the disease) illustrates that comp is not
even verifiable by oneself (the first person one).
Of course, for someone who assumes comp at the start, this
uncommunicability is the same as the one related to *any* form of
survival, including anesthesia, night sleep or just the experience of
drinking a cup of coffee.
But I do argue that comp is *refutable*, because comp does put total
constraints of the laws of physics (cf the reversal).


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Received on Mon Jun 26 2006 - 05:25:25 PDT

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