On Thu, Jun 16, 2005 at 03:37:05PM +0200, Bruno Marchal wrote:
> Le 15-juin-05, ? 01:39, Russell Standish a ?crit :
> >On Tue, Jun 14, 2005 at 04:39:57PM +0200, Bruno Marchal wrote:
> >>
> >>
> >>OK but it can be misleading (especially in advanced stuff!). neither a
> >>program, nor a machine nor a body nor a brain can think. A person can
> >>think, and manifest eself (I follow Patrick for the pronouns) through 
> >>a
> >>program, or a machine or a brain, ....
> >
> >Actually, I think I was the one introducing these 3rd person neutral
> >pronouns (e, er & em). I picked up the habit from Michael Spivak
> >(well known mathematician).
> >
> >Doesn't this beg the question a bit as to what a "person" really is?
> >In loose everyday conversation, a person is a member of the species
> >homo sapiens. However, surely we don't want to rule out the
> >possibility of other conscious things before we even start. And also
> >as you mention below, there are odd corner cases - the sleeping human
> >being etc.
> I just identify the first person with the knower. Think about someone 
> being "cutted" in Brussels and being pasted in thwo cities: A and B, 
> and nowhere else. Each copy makes an experience, one in A, the other in 
> B. Each of them know where they have been reconsituted and so each of 
> them get one bit of information. But this bit is uncommunicable from a 
> third person point of view. An outsider would get 0 bit from a phone 
> call by each copy (by default I assume the cut/past device is 100% 
> reliable.
> I identify the third person with the body or with any third person 
> description of the body, it could be program (with comp). Despite 
> Jonathan (I know you agrees with me) I consider as fundamental to 
> distinguish the 1-person knower from the 3-person body/brain/program. 
> So when I say that only a person can think, I am really meaning a 
> 1-person.

Ah - 1st person helps nail down what you mean. I do distinguish
between 1st person and 3rd person, but would probably use the same
language to describe the two different cases:

1. The mind thinks (1st person)
2. The brain thinks (3rd person)

Of course the word "thinks" has a different meaning in these two
different cases, so obviously there is the potential for confusion if
not properly qualified in some circumstances.

However if you say that just the mind thinks, then I suspect you _are_
implicitly supporting a type of dualism that Jonathon Colvin is trying
to nail me with :)

> >>>Church-Turing thesis and arithmetical platonism (my all
> >>>description strings condition fulfills a similar role to arithmetical
> >>>platonism) are enough.
> >>
> >>
> >>I am not so sure. You are not always clear if the strings describe the
> >>equivalent of a program (be it an universal program or not), or
> >>describes a computations (be it finite or infinite).
> >
> >Both actually. One can feed a description into the input tape of a
> >UTM, hence it becomes a program. They may also be generated by a
> >program running on a machine.
> I was not making that distinction. I was distinguishing between a 
> program (being a product of another program or not) and the 
> computation, that is the running of the program. The computation can be 
> described by the description of the trace of the program (like when we 
> debug a program). For example the basic program "10 goto 10" has an 
> infinite trace, like 10 10 10 10 10 10 10 ...
> That distinction is primordial for the understanding of the work of the 
> Universal Dovetailer which dovetails on all programs. The UD generates 
> all programs and dovetail on all their executions. The possibility or 
> consistency of this is a consequence of Church's thesis.

Since I merely posit that all descriptions are there (by virtue of the
zero information principle), the descriptions are not actually supposed
to have been generated by a program. However, a la Schmidhuber they
could be. They are, however interpreted by an observer, which in the
computationalist case would correspond to them being run as a program.

Does that then answer the question?

> >There are various strengthenings of the CT thesis which are far from
> >obvious, and even false in some cases. One of my criticisms of your
> >work is that I'm not sure you aren't using one of the strong CT
> >theses, but we can come back to that.
> I am using the original thesis by Church, Post, Markov, Turing, ... 
> They are equivalent and can be summarizes "anachronically" by all 
> universal digital machine computes the same functions from N to N.

Hmm - this is really a definition of a universal machine. That such a
machine exists is a theorem. Neither depend on the Church-Turing
thesis, which says that any "effective" computation can be done using
a Turing machine (or recursive function, or equivalent). Of course the
latter statement can be considered a definition, or a formalisation,
of the term "effective computation.

> Instead of saying that comp entails that machine can think, it is less 
> misleading to say that comp entails machine can vehiculate a knower, 
> who is the one which can think. The day "we" can be vehiculated through 
> the net in digital form, people will learn that difference by 
> experience ...
> Bruno
> http://iridia.ulb.ac.be/~marchal/

Well we could, but sometimes all that extra verbiage makes the
arguments more confusing. Never mind - communication is always an
imperfect science, in spite of mathematicians' prejudices :)

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A/Prof Russell Standish                  Phone 8308 3119 (mobile)
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