On 21 Apr 2015, at 00:43, Bruce Kellett wrote:
Bruno Marchal wrote:
On 20 Apr 2015, at 09:40, Bruce Kellett wrote:
Dennis Ochei wrote:
One must revise the everyday concept of personal identity because
it isn't even coherent. It's like youre getting mad at him for
explaining combustion without reference to phlogiston. He can't
use the everyday notion because it is a convenient fiction.
I don't think phlogiston is an everyday concept. The closest
continuer concept of personal identity is far from an
unsophisticated everyday notion, or a convenient fiction. If you
want to revise it to some alternative definition of personal
identity that is better suited to your purposes, then you have to
do the necessary analytical work.
Are you saying that you believe that computationalism is false (in
which case you can believe in some closer continuer theory), or are
you saying that step 4 is not valid?
I am suggesting that computationalism is effectively false,
OK. But that is out of the topic.
in part because of an inadequate account of personal identity.
Computationalism by definition makes simple teleportation, and
duplication, supporting the subjective feeling of personal identity.
So we don't need any account of personal identity, except the
acceptance of a an artificial brain, seen as a clinical operation like
another one. If not you should not even take an aspirin, as you would
need some adequate account of personal identity to be guarantied that
you will survive when you take that aspirin, or when you just drink
water, or even when you do nothing.
The situation would be different for someone claiming having the right
Turing program for the functioning of the brain, but comp just assumes
such program exists. Indeed, in the mathematical part, it is proven
than no machine can know for sure what is its own program, and that is
why the "it exists" in the definition is non constructive, even
necessarily non constructive (as Emil Post already saw) and the act of
saying "yes" ask for some an act of faith.
You substitute part or all of the brain at some level with a Turing
machine, but do not take appropriate notice of the body bearing the
brain.
If the body is needed it is part of the 'generalized brain'. Even if
that is the entire universe (observable or not), the reasoning still
go through. This should be clear if you have grasped the argument up
to step 7.
If we are not to notice the substitution, we must still have a body
that interacts with the world in exactly the same way as the
original. Under the teleportation scenarios, some new body must be
created or provided. I think that in general the person might notice
this.
You need a perceptual body, as in step 6. With computationalism you
cannot notice the difference introspectively, and that is all what
counts in the reasoning.
If you woke up in the morning and looked in the mirror and saw
Sophia Loren looking back at you, or saw your next door neighbour in
the mirror, you might doubt your own identity. Memories are not
everything because memories can be lost, or be mistaken.
Not in the protocol used in the reasoning. You distract yourself with
ideas which are perhaps interesting for some debate, but are not
relevant to understand that computationalism makes physics into a
branch of arithmetic.
In total virtual reality scenarios, of course, this could be
managed, but then you have the problem of the identity of
indiscernibles. Creating copies that are identical to this level --
identical memories, bodies, environments, and so on -- does not
duplicate the person -- the copies, being identical in all respects,
are one person.
That is correct.
Of course in step 6, the copies diverge because they are simulated in
simulation of Moscow and Washington. Like in step 7 they will diverge
on all ... diverging histories.
I am saying that a case could be made that all the destructive
teleportation scenarios create new persons -- the cut actually
terminates the original person.
Then you can't accept a digital brain proposed by the doctor, and comp
is false (which is out of topic).
In step 3 you have a tie for closest continuer so there is no
continuing person -- the original is cut. If the original is not cut
(as in step 5), then that is the continuing person, and the
duplicate is a new person. Time delays as in steps 2 and 4 do not
make a lot of difference, they just enhance the need for the
recognition of new persons.
if comp is false, the reasoning just don't apply.
In sum, your argument over these early steps is not an argument in
logic,
?
An argument is valid, or is not valid.
but an argument of rhetoric. Because the tight definitions you need
for logical argument either are not provided, or when provided, do
not refer to anything in the real world, at best you are trying to
persuade rhetorically -- there is no logical compulsion.
Argument?
What you are talking about has more to do with psychology and/or
physics than mathematics,
I call that theology, and this can be justified using Plato's notion
of theology, as the lexicon Plotinus/arithmetic illustrates. The name
of the field is another topic.
Also, you are unclear. you argue that comp is false, but reason like
it makes sense, and that the reasoning is non valid, without saying
where is the error. It is hard to figure out what you mean.
so definitions can never be completely precise
That never happens, even in arithmetic. That is why logic is used: to
reason in a valid way with incomplete and imprecise notions. You seem
to believe that something is non valid, but failed to say what. Adding
precisions when it is not needed only obscure your point.
-- concepts in the real world are always corrigible, so tightly
constrained logical arguments are not available as they are in
mathematics.
Not if you use an hypothesis, like computationalism, which makes
possible to reason clearly, and eventually to get testable conclusion.
This is made mathematically possible thanks to Church's thesis (also
used in step 7, though).
If you have trouble with thought experiences, you might directly study
the mathematical theory, but you need to study some textbook in
mathematical logic and theoretical computer science. Personal 3p-self
is defined with the second recursion theorem of Kleene, and the first
person self is defined from the old idea by Theaetetus in Plato,
applied to the 3p-self.
Of course, if you have an alternate non-computationalist theory of
mind, you are free to expose it. But you cannot use it in a so direct
way to invalidate a reasoning made in a different theory. That simply
does not work.
Bruno
http://iridia.ulb.ac.be/~marchal/
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