On 23 Aug 2014, at 06:02, meekerdb wrote:
On 8/22/2014 6:46 PM, David Nyman wrote:
I must confess that I've been reading the MGA revisited thread with
a certain sense of frustration (notwithstanding that Russell has
made a pretty good fist of clarifying some key points). My
frustration is that I have never been able to see why we need an
elaborate reductio like the MGA to dispose decisively of a
*computational* theory of mind on the basis of a primitive
materiality. The crux of the argument is whether the
"computational" part of the theory can be reduced without ambiguity
to the action of a physical device (e.g. a computer or a brain). If
not, what we're left with looks like a crypto-materialist theory in
computationalist disguise. In point of fact I agree with Stathis
that multiple realisability is already sufficient to establish this
point. But let me elaborate a little further. When we consider the
matter, we don't actually observed "computation" (in any rigorous
mathematical sense) in physical reality. What we observe in
practice are physical devices of various kinds (indeed, in
principle, indefinitely many kinds) that we accept FAPP as
adequately instantiating particular classes of computation within
certain fairly stringent limits.
What we observe, aside from observing our own thoughts and maybe
even then, is always theory laden. Partly we see the world through
a theory of objects that evolution has provided us, sort of naive
physics, but a theory nonetheless as optical illusions demonstrate.
To put it another way, we are prepared to interpret the normal
physical behaviour of such devices *as if* it instantiated the
mathematical notion of computation.
Right, because it usually (modulo a dropped bit or so) does.
But at all times it is sufficient to assume that such behaviour, be
it of computers or brains, is constrained exclusively and
exhaustively by physical law. It's their net action, as physical
devices, that is at all times assumed to be essential, whatever
"computational" (or other) interpretation may be ascribed to them
externally. Unfortunately, these otherwise rather obvious facts
tend to be obscured in ordinary, and even in technical, discourse
by the free intermixing of software and hardware paradigms.
These considerations should make it clear that any description of
the normal behaviour of a physical device as computation can only
be in a sense that is, ultimately, metaphorical.
I think you are too hung up on ontology. You denigrate everything
that's not in terms of the ur-stuff of (some unknown) true ontology
as metaphor or fiction. Why not accept that knowledge, including
knowledge of ontology, is always provisional and uncertain and it's
best to think of it as a model summarizing our best idea - but not
necessarily the one TRUE idea.
This extends to any software re-description of physical action, as
for example Brent's Mars Rover analogy, or Dennett's
"third-person absolutist" take on perception and cognition. On the
assumption of a "primitive physical reality", such descriptions can
(and indeed must) be understood as metaphorical and approximate,
not literal and "absolute".
Suppose the "physical reality" isn't primitive. So what? Molecules
aren't primitive, even atoms aren't primitive. But we can still
describe life in terms of certain processes at the molecular level.
They are grounded in the assumption of their ultimate reducibility,
and approximate equivalence, to some kind of net physical action.
In this light, physical devices don't literally "compute"; the most
we need to say is that their physical behaviour adequately
*approximates* computation, under suitable interpretation and
within certain limits. Under such constraints, it would seem that a
so-called "computational" theory of mind could in fact amount to
nothing other than the claim that consciousness is a *state of
matter*. This particular state of matter, it would be claimed, must
obtain whenever physical action happens to be approximately re-
describable (at some arbitrary level) in terms of a certain class
of computation.
I'd say that pretty much the standard physical account of
consciousness.
But given that the theory is grounded, and is at all times
expressible, in terms of an explicitly physical, as distinct from
mathematical, ontology, it is hard to discern how such a
"computational" stipulation could contribute anything intelligible
to the claim.
It adds a great deal of intelligiblity, just as explaining how
organic molecules manage to perform metabolism, growth, and
reproduction and to evolve as part of living entities. There's lots
of stuff we can't understand at the level of 10^32 atoms but which
we easily grasp at the level of a table and chair. That doesn't
mean we've invoked some magic.
ISTM that the foregoing considerations are sufficient, on their own
merits, to establish the necessity of the reversal at Step 8, if a
*computational* (as distinct from some sort of tacitly crypto-
material) theory of consciousness, is to be salvaged.
ISTM that's like saying I'm not going to consider CTM unless it can
saved from being merely useful and/or approximate and shown to be
absolute.
If so, it is indeed clear that the task becomes at least twice as
hard as before, as the observed correlations between matter and
consciousness now have to be justified on the basis of an ontology
that is (mathematically) adequate for a general and rigorous (as
distinct from local and approximate) emulation of computation.
I don't think it's any harder than the problem that Bruno created in
the first place by taking computation as basic. That means that
mind AND matter have to be explained as computation. It may make
the mind part a little easier, but I think it leaves the matter part
pretty hard.
Hard, but at least mathematically formulable. And then it is solved at
the propositional level.
Even if that solution happens to be false, it is a progress because it
is testable: compare a material hypostase logic (the comp-QL) with
QL, and if you find a difference, test it in the laboratory. If nature
confirms QL, and not the comp-QL, it means that either we are dreaming
or in a normal emulation (like a Bostrom one, that is a programs
concretely made by our descendants) or classical comp is false, and
that would mean that comp is false or that the current treatment of
knowledge (obeying S4, recoverable by Theaetetus, etc.) is inaccurate.
In any case we learn something.
Meanwhile, we get an arithmetical interpretation of a non-aristotelian
"theology", which weaken the prejudice that you need to be (weak)
materialist to be a scientist, and like Gödel's proof of the existence
of St. Anselm based on the alethic modal logic S5, it illustrates that
we can do theology in the hypothetico-deductive rigorous way.
Physics is a wonderful science, but as a theology, it still miss even
the formulation of the questions. The physicists don't address the
question, except indirectly in some theoretical interpretation of
their theory, but the paradimatic idea that physics *is* the
fundamental science relies on accepting some theological axioms of
Aristotle, which, I think, are undermined by both the QL data, and the
consequences of computationalism in "philosophy of mind".
Bruno
Brent
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