On 06 Feb 2011, at 23:15, Andrew Soltau wrote:
Hi Bruno
I will attempt to define the terms in a manner satisfactory to both
of us, and maybe we will understand each other this way.
CTM Computational Theory of Mind is the concept that "the mind
literally is a digital computer ... and that thought literally is a
kind of computation."
from
http://plato.stanford.edu/entries/computational-mind/
So you can see that comp, as defined in sane04, is a weaker version of
CTM. (And thus all consequences of comp are inherit by CTM).
Expression like "mind is a digital computer" are category error, and
is also ambiguous. It relates also on the identity thesis in the
philosophy of mind, which is actually incompatible with comp (and thus
with CTM). I think that it is also incompatible with QM, but that is
out of topic.
With comp you can associate a mind to the execution of a computer, but
you cannot attach a computer to a mind. You might attach an infinity
of computer executions to a mind. The relation is not one-one. That is
among other things a consequence of UDA.
To say that thought literally is a kind of computation is ambiguous.
That might be enough in some context, but the more precise comp is
needed to understand the comp (and thus CTM) necessary reduction of
body to mind, or of physics to arithmetic (or computer science).
I understand your steps one to seven to be making this point.
I have no difficulty with this point.
Which point? The first seven steps of UDA makes the following points:
1) that comp entails the existence of first person indeterminacy in a
deterministic context. Step 1-3. This is an original result that I
published in 1988 (although I made a dozen of conference on this in
the seventies). Many academics have criticize this, but their argument
have been debunked. Chalmers did criticize it at the ASSC4.
2) that any measure of uncertainty of the comp first person
indeterminacy is independent of the reconstitution delays (step four).
3) that comp entails first person non locality (step this has been
more developed in my thesis, long and short version are in my web
page). This has been retrieved from sane04 (for reason of place), but
is developed in the original 1994 thesis (and in the 1998 short
version, recently published).
4) That first person experience does not distinguish real from virtual
implementation (this is not original, it is in Galouye, and it is a
comp version of the old dream argument in the greek chinese and indian
antic literature). Step six. In particular indeterminacy and non
locality does not depend on the real or virtual nature of the
computation.
Step seven itself shows the reversal between physics and arithmetic
(or any first order theory of any universal system in post Church
Turing sense) in case the physical universe exists primitively and is
sufficiently big.
So UDA1-7 is the one of the main result of the thesis. A theory which
want to explain and unify quanta and qualia, and respect comp, has to
derive quanta and qualia without postulating them.
You have also that comp + ~solipsisme entails first person plural MW.
Normally comp should imply ~solipsisme, but as I explain this part is
not yet solved in the concrete.
Now most people (among interested) understand UDA1-7, that is, that
comp + *very big* universe entails the reversal. If you have no
problem with the first person indeterminacy, with the invariance for
reconstitution delays, with the inability of first persons to
distinguish (in short time) real and virtual, I don't see what you
miss in the step seven. 7 is a direct consequence of 4,5,6.
Step 8 extends the invariance: it shows that we cannot distinguish
virtual reality with arithmetical reality, so we don't need to run
physically (and BTW, what would that mean?) a universal dovetailer to
get the global first indeterminacy (the one based on a "running" UD).
So step 8 just shows that we don't need the assumption of a big
universe to get the reversal.
I told the list that a scientist thought having find a refutation of
UDA. I got it, and it was that: I would have forget that we might live
in a little physical universe. My answer is just a reference to step
8. So later he replied with the idea that the movie-graph can think.
That's a progress. Now, I have debunked more than once on this list
the idea that a movie can think. (It is an error akin to the confusion
between a number and a gödel number of a number, a confusion between a
description of a computation and a computation, it is a confusion of
the type finger and moon (ultrafrequent in the field).
Of course, even without step 8, UDA1-7 is already very nice given that
it shows the reversal in the case of 'big universe', and in passing
shows that digital mechanism (comp) entails indeterminacy, non
locality, and non cloning of matter. Of course the white rabbits
remains and have to be hunted away, if we want to keep comp (and thus
CTM, given that CTM implies comp).
This is what seems straightforward to me.
Thought is a computation. OK.
Experiential reality is a computation. OK.
No. When you say "experiential reality" is a computation, you are
saying something ambiguous, where comp is far more precise. Because if
I can survive with a digital brain, then the experiential reality, the
first person, subjective, experience is not a attachable to a
computation, but to an infinity of computations, and it obeys a logic
driven by the knowing arithmetical points of view, which makes it
closer to the non computable notion of "inner god" than to a 3-person
computation. The first person cannot even describe (or name, in the
logician terms) itself.
It might seem amazing, but when you take comp (which implies CTM) you
eventually see that neither experiential nor experimental reality are
computational. Universal numbers leaves in a ocean of non computable
numbers.
Also, when you say computation, people can still confuse a computation
with a physical implementation of that computation.
New Point
Chalmers defines a 'Computational Hypothesis'
You might attribute this to Putnam or Fodor, or many others, including
Galouye. That's CTM. I argue that the computationalist hypothesis is
already in the "King Milinda" text, which is a greec-hinduist text
from before JC.
You can see CTM as an ancestor of the more precise modern comp (TC +
yes doctor). The "yes doctor" is a belief in a level of description,
where CTM believes implicitlt that we know the level (neuron level,
for example). But as Colin explains we might take into account the EM
fields. I argue that we have to take into account the glial cells (100
time more numerous than the neurons). No problem with comp, the level
might be as low as the 10^1000 rational cut of the heisenberg matrix
of the milky way at the dimension of the superstrings.
The Computational Hypothesis says that "physics as we know it is not
the fundamental
level of reality."
Give me the reference. Chalmers opposed me on this at the ASSC4. This
is a consequence of comp, not a direct consequence. Indeed it is the
result of my thesis that many oppose ((but rarely publicly for some
reason) since I published it in 1988. Just read the archive on this
list. Most materialist and atheists believe that physics describes the
fundamental level of reality, and today virtually nobody has seen that
it cannot be so. Only Wheeler wrote an explicit paper where he
suggests that physics might rely on a deeper non physical theory. See
Laws without laws, and david Deutsch critical reply.
and
"Just as chemical processes underlie biological processes, and
microphysical
processes underlie chemical processes, something underlies
microphysical processes.
Give me the reference. I would appreciate if Chalmers changed his mind
on this. I would appreciate even more if he refers to my work, given
that he knows its existence.
Underneath the level of quarks, electrons, and photons is a further
level: the level of bits.
I sort of agree, like Wheeler on this. Typically physicists, like
Deutsch and Landauer for example, replies that the further level is
quantum bit, and that if nature is made of information, it is quantum
information. but I do think that even quantum information comes from
the bits (and the perspectival nature of the observers).
These bits are governed by a computational algorithm, which at a
higher level produces the
processes that we think of as fundamental particles, forces, and so
on."
That is digital physics, and I can explain that comp negates digital
physics. If I am a computer, then physical reality is not a computer.
Physical reality become non totally Turing emulable.
This is what you claim to have established around point 7 in your
paper.
Step seven establish that physics is a branch of arithmetic. That
schroedinger equation has to be redundant. Step 1-7 is the reduction
of the mind body problem to a purely mathematical body problem. It is
the contrary of the idea that particles and fileds result from a
classical algorithm. And the math part shows the details of this and
makes physics a non computable (a priori) integration (sum) on all
'arithmetical fictions'.
With step seven you know that the TOE is just logic + addition and
multiplication:
x + 0 = x
x + s(y) = s(x + y) laws of addition
x*0 = 0
x*s(y) = x*y + x laws of multiplication.
AUDA is based on the fact that in that theory you can define Gödel's
beweisbar (provability predicate) "B", and physics, including the
justification of the wave equation (if that is correct) arise from the
behavior of Bp & Dp. The interest here relies on the fact that the G/
G* splitting inherited by Bp & Dp leads to a general unified theory of
qualia and quanta.
I don't expect you to really understand this without studying some
good textbook in logic. A good one is the book by Boolos and Jeffrey
(and Burgess for ulterior edition).
UDA can already been seen as a popular (human) presentation of AUDA. I
have always done them together.
I do not follow the step from CTM to a Computational Hypothesis.
(no, your last explanation did not help)
CTM is the (fuzzy) idea that the mind function like a software
processed by a natural computer (the brain). OK?
Comp can be seen as more precise, more rigorous and much more weak
version of CTM.
CTM implies COMP, and COMP does not imply CTM.
Like we have that COMP implies STRONG-AI, but STRONG-AI does not imply
COMP (machine can think does not logically entail that only machine
can think).
Comp makes precise that saying to be a machine is equivalent with
saying that there is a level of functional substitution where my
(first person) consciousness is invariant for a substitution made at
that level. Comp can show that we can never known our level of
substitution, and my reasoning works whatever I mean by my brain (it
could be the entire galaxy or the entire observable universe if
someone asks for it). CTM is vague on the level, and miss the point
that we cannot know it, if it exists.
Comp is also much more general than CTM, which relies usually on some
amount of neurophilosophy, or on representationalist theory of the
mind, and CTM is often criticized by 'externalist', like brent Meeker
for example. But comp is not annoyed by externalism, given that it
defines the (generalized) brain by the portion of universe you need,
like possibly the matrix above.
So comp is a very weak, and thus general, hypothesis. And the result
is easy to describe: physics is not the fundamental branch. Computer
science is (or arithmetic, in the large sense of the study of
arithmetical truth (like with Number Theory) because computer science
can be be embedded in number theory, unlike most of mathematical
logic, note. Note also that usual mathematics (math without categories
and mathematical logic) can probably be embedded in arithmetic: open
problem).
So comp is more precise, and more general. To sum up. What you deduce
from it will be too.
Bruno
http://iridia.ulb.ac.be/~marchal/
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