On 06 May 2009, at 11:35, Torgny Tholerus wrote:

> Bruno Marchal skrev:
>> Something conscious cannot doubt about the existence of its
>> consciousness, I think, although it can doubt everything else it can
>> be conscious *about*.
>> It is the unprovable (but coverable) fixed point of Descartes
>> systematic doubting procedure (this fit well with the self-reference
>> logics, taking consciousness as consistency).
>> Someone unconscious cannot doubt either ... (A zombie can only fake
>> doubts)
> Yes, you are right.  I can only fake doubts...

I suspect you are faking faking doubts, but of course I cannot provide  
any argument.
I mean it is hard for me to believe that you are a zombie, still less  
a zombie conscious to be a zombie!

>> We live on the overlap of a subjective un-sharable certainty (the
>> basic first person knowledge) and an objective doubtful but sharable
>> possible reality (the third person belief).
>> To keep 3-comp, and to abandon consciousness *is* the correct
>> materialist step, indeed. But you cannot keep 1-comp(*) then, because
>> it is defined
>> by reference to consciousness. When you say "yes" to the doctor, we
>> assume the "yes" is related to the belief that you will survive. This
>> means you believe that you will not loose consciousness, not become a
>> zombie, nor will you loose (by assumption) your own consciousness, by
>> becoming someone else you can't identify with.
> I can say "yes" to the doctor, because it will not be any difference  
> for
> me, I will still be a zombie afterwards...

  I don't know if you do this to please me, but you illustrate quite  
well the Löbian "consciousness" theory.
Indeed the theory says that "consciousness" can be very well  
approximated logically by "consistency".
So a human (you are human, all right?) who says "I am a zombie", means  
"I am not conscious", which can mean "I am not consistent".
By Gödel's second theorem, you remain consistent(*), but you loose  
arithmetical soundness, which is quite coherent with your  
ultrafinitism. If I remember well, you don't believe that there is an  
infinity of natural numbers, right?

We knew already you are not arithmetically sound.  Nevertheless it is  
amazing that you pretend that you are a zombie. This confirms, in the  
lobian frame, that you are a zombie. I doubt all ultrafinitists are  
zombie, though.

It is coherent with what I tell you before: I don't think a real  
ultrafinitist can know he/she is an ultrafinitist. No more than a  
zombie can know he is a zombie, nor even give any meaning to a word  
like "zombie".

My diagnostic: you are a consistent, but arithmetically unsound,  
Löbian machine. No problem.

There are not many zombies around me, still fewer argue that they are  
zombie, so I have some questions for you, if I may.

1) Do you still answer yes to the doctor if he proposes to substitute  
your brain by a sponge?
2) Do humans have the right to torture zombie?
3) Do you have any "sort-of" feeling, insight, dreams, impression,  
sensations, subjective or mental life, ... ?
4) Does the word "pain" have a meaning for you? In particular, what if  
the doctor, who does not know that you are a zombie, proposes to you a  
cheaper artificial brain, but warning you that it produces often  
unpleasant hard migraine? Still saying yes?


(*) For example: Peano Arithmetic + "Peano Arithmetic is inconsistent"  
gives a consistent theory. If not, Peano Arithmetic + "Peano  
Arithmetic is inconsistent" would prove "0=1", and thus PA would prove  
~(provable "Peano Arithmetic is inconsistent" ), and thus PA would  
prove its own consistency, contradicting Gödel II.


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