On 25 Jan 2011, at 15:47, Stephen Paul King wrote:
The supervenience thesis is separate from the Turing thesis and
Mauldin does a good job in distinguishing them.
Just to be clear, what Maudlin call "supervenience thesis" is what I
called "physical supervenience thesis", to distinguish it from the
computationalist supervenience thesis.
The computationalist supervenience thesis is basically what remains
when we keep comp, and understand that the Phys. Sup. thesis has to go
away in the comp frame.
The problem that I see is in the properties of physicality that are
assumed in Mauldin’s argument. It is one thing to not be dependent
on what particular physical structure a computation can be run on
(assuming a realistic supervenience), it is another thing entirely
to say that a Turing machine can be “run” without the existence of
any physical hardware at all.
Well, in the branch ~MEC v ~MAT, Maudlin seems to prefer MAT, so he
seems with you on this, I think.
I am trying to make this distinction and trying to fix this problem
that I found in the supervenience thesis within Mauldin’s argument.
He does point out that there are contrafactuals that must have some
physical instantiation. We see this on page 411 where he wrote:
“The only physical requirement that a system must met in order to
instantiate a certain machine table are that (1) there must be at
least as many physically distinguishable states of the system as
there are machine states in the table, (2) the system must be
capable of reacting to and changing the state of the tape, and (3)
there must be enough physical structure to support the subjunctive
connections specified in the table.”
It is in the subjunctive connections that we see the
contrafactuals expressed. If one’s model of physical reality does
not allow for the necessary subjunctive connections to be
implemented then the supervenience thesis would fail independent of
the Turing thesis.
OK.
My point is that we need to be careful about what exactly do we mean
by “causally inactive piece of matter”. If there is material present
within a physical system that does not affect the 3 requirements
above then surely we can agree with Mauldin’s claim, but if there is
a problem with the faithfulness of the model of what physicality
involves, then this must be fixed if possible. This is why I say
that there is a bit of a straw man in his argument.
Maudlin should have said: "causally inactive piece of matter
*relevant* for the computation. This is what I did, and it makes the
argument independent of the counterfactual re-instantiation. The movie-
graph is simpler with that respect. But this can lead to some
ambiguity too.
Mathematical structures do not “do” anything, they merely exist,
if at all! We can use verbs to describe relations between nouns but
that does not change the fact that nouns are nouns and not verbs.
The movie graph is a neat trick in that is abstracts out the active
process of organizing the information content of the individual
frames and the order of their placement in the graph, but that some
process had to be involved to perform the computation of the content
and ordering cannot be removed, it is only pushed out of the field
of view. This is why I argue that we cannot ignore the computational
complexity problem that exist in any situation where we are
considering a optimal configuration that is somehow selected from
some set or ensemble.
I don't see how this would change anything in the argument, unless you
presuppose consciousness is not locally Turing emulable, to start with.
Another question that I am asking is what relation does
information have with matter. We had a paper that seems to propose
that information is physical and then goes on to make some strange
claims.
OK. And the problem with the word physical is that it means different
things in different settings. The main confusion is between
fundamentally physical, or material, with a conception of primary
matter, or it means "related to this or that physical theory" based on
abstract mathematical relations.
We also had a recent paper that discusses how “information is
converted into free energy” by a Maxwell Demon-type feedback system.
It seems to me that there is a lot of confusion about what
relationship there is between information and matter, so my
inquisitiveness could be seen as an attempt to make sense of this
mess.
And the word "matter" is similarly ambiguous, and never defined,
except by Aristotle which provides the "& Dp" idea, implicitly used by
the Platonist Plotinus to define matter in the way used by the self-
observing machine.
Matter is what is indeterminate, and oppose to intelligibility (Bp).
It is of the type ~Bp, that is D#. This is coherent with the idea that
a physics is, before all thing, a probability or plausibility
calculus. Cf also Timaeus (Plato) bastard calculus, and the Kripke
semantics of "Dp" in modal logics: Dp = it exists a world satisfying p.
One idea that could be proposed is that information is a
relationship in a triple such that a difference exists between two
that makes a difference for the third. I am sure that this can be
put into more formal terms. Turing Machines aside, we are not really
getting to the problem until we have a good set of tools with which
to examine the question of how to determine the substitution level
of a given system and even if substitution is possible.
Here I disagree 100%.
It is proved that if we are machine, then we cannot define and prove
what is our substitution level. No machine can ever know which machine
she is. This is what I have called the Benacerraf principle in older
post (and my theses).
For any machine defined as such in a 3-way, the substitution level is
built in the plan of the machine, by definition.
We can play with theoretical concepts and toy models all of our
lives, but if and until they have concrete physical realizations
they are mere figments of our imaginations.
I disagree again. We can use them as theoretical tools. Most of
theoretical computer science is not constructive, and most of the
times necessarily and provably so. That is another reason why it is
closer to theology than to engineering.
Bruno
PS I know you are dyslexic, so I just tell you that the "L" in
MAUDLIN, is after the "D", not before.
http://iridia.ulb.ac.be/~marchal/
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