On 7/30/2014 5:36 AM, David Nyman wrote:
On 30 July 2014 09:03, Bruno Marchal <[email protected]
<mailto:[email protected]>> wrote:
I think (maybe pace David) that materialism explains well consciousness, by
using
comp. The problem is that such explanation makes *matter* incomprehensible.
Well I must confess I'm not entirely pacified yet. Surely the whole point is that if the
second sentence is true it contradicts the first! If the assumption that materialism can
use comp to explain consciousness in fact leads to the absurd conclusion you describe,
then materialism *cannot* use comp to explain consciousness, well or otherwise.
The trouble is, there are a lot of nuances that tend to obscure the logical steps of the
argument, particularly in assumptions about the scope of "reasonable" explanation. Brent
and others point to parallel accounts of neural activity and conscious self-reporting
and ask "what more could be required in the way of explanation?". AUDA may indeed give a
clue to the direction in which explanation could be extended, beyond ostensive
parallelism of this kind, particularly with respect to the central logical puzzles of
mutual reference between 1p and 3p regimes. But this would require us to relinquish any
prior commitment to primitive materialist assumptions.
There are no such commitments - just requests that other theories meet the same standards
of empirical prediction.
My recent forays into thought experiment have been an attempt to articulate my own
(still persisting) intuitions about the intrinsic limitations of reductionist
explanation under strictly materialist assumptions (i.e. without either tacit or
explicit reliance on supernumerary posits). ISTM that one of the problems in reaching
any kind of stable agreement (or even disagreement) on these issues is equivocation over
the terms of reference. Consequently I've tried to make my own view of the reductionist
assumption clear: i.e. that explanation of phenomena at any level whatsoever can in
principle be reduced without loss to accounts of the action of a finite class of
"primitive" physical entities and relations. Of course, this tends to lead to
disputation over the sense of "without loss", but I'll come to that in due course.
But you assume a cartoon version of reduction to "primitive physical entitities". You
seem to envision the atoms of Democritus. If you read some modern physics you'll find
that (as Bruno sometimes points out) primitive physical matter is never defined or even
mentioned. Many physicists hope to base their theories on information. Some on 'strings'
in very abstract, 11 dimensionsal spacetime. Some propose to make spacetime a derivative
phenomena. So you need to think about what exactly you are attacking as "reductionism".
ISTM that it's any theory that doesn't take consciousness as primitive.
Stated thus baldy and strictly eschewing equivocation, reductionism entails that it is
misleading to consider any derivative phenomenon, above the level of the chosen
explanatory basement, as having "independent existence".
But only in a narrow sense of "independent".
Strictly speaking (and strictness is essential for the succes of the argument) such
phenomena are both explanatorily and ontologically dispensable.
?? A good explanation must always be in terms of something understood. We understand our
perceptions and we infer a material world. I think you must have some restricted concept
of "explanatory" in mind and I think it is implicitly "explanation in terms of physical
causation."
It's just that in extenso the proofs are a little longer! I've offered analogies in
terms of such things as societies and football teams (you can easily supplement these
with your own) in terms of which this consequence of reductionism is rather obvious.
But for some reason it stops being "obvious" in the matter of matter itself. On
reflection, the reason is not so elusive: i.e. we "directly experience" such
higher-level phenomena in an unreduced form. Hence none of us (and that includes
Professor Dennett) can avoid the fact of encountering, and discoursing in terms of, a
"reality" in unreduced high-level terms, even though our "best" explanations actually
rule out the other-than-metaphorically-independent significance of any such levels.
Now you mix in "significance" - having value or standing in place of something?
If you doubt the degree of cognitive dissonance this engenders, consider the general
tenor of disputes over "free will".
This is the point at which the parallel with any other reductionist analogy breaks down.
Nobody would seriously claim, beyond a manner of speaking, that football teams amount to
anything other than the aggregate action of the persons that constitute them. But on the
other hand almost everyone (pace Daniel Dennett) would claim direct access to a reality
that is something (even if we can't agree exactly what) that is, at least, categorically
distinct from any description of the aggregate action of the material processes of the
brain.
"Categorically"? We make up categories. How about distinct from any description of the
computational processes of the brain?
The same distinction, however, can't be claimed for "computation", on the assumption of
material reduction. Just as in the case of the football team no instance of computation
can escape reduction to material tokens that have been contrived, under suitable
interpretation, to embody the necessary physical action.
But what interpretation is suitable? and what is the role of this
interpretation?
There isn't even the saving grace that we directly perceive computation in unreduced
form. What we actually perceive are macroscopic physical devices that, by assumption,
produce all their effects entirely in terms of basic material processes that are fully
subject to reductive explanation. Every explanation we give in terms of computation can
in principle be replaced without loss by a description of a physical process.
Really? Do we not have to specify initial conditions to give an explanation in terms of
physical processes?
This is the underlying reason that Alice's net behaviour can persist unaltered even
after disruption of any putatively "computational" organisation of her brain. Under
physicalist assumptions, Alice is first, last and always a physical device. Indeed, were
that not the case, it would be difficult to see how any "physical computer" could ever
be manufactured! On this analysis then, it can hardly be coherent to claim that any
association between consciousness and matter obtains "qua computatio". If any such
association were to obtain under these assumptions, it would perforce be "qua materia".
The worrying thing (and it worried me even more in the light of your recent objections)
is not that this analysis lacks power, but rather that the "flesh-eating microbe" of
reductionism might devour even the computational structures putatively derivable from
simpler number relations and hence nullify comp. My own intuition (still under review I
admit) is that in an important sense realism about these structures depends ultimately
on their generalised epistemic consequences. Is 17 prime independent of anyone's knowing
it? My response to this oft-posed question is that if such putatively significant truths
do not actually entail somebody's knowing them, their possible consequence may be moot.
Certainly any mathematics devoid of such epistemic consequence could play no role in comp.
There are no primes in the real numbers - and analog computers existed before
digital ones.
Arithmetic is postulated in the first instance as an ontology whose truth is entirely
"independent of us" but then the (truly surprising) discovery is elucidated that such
truths turn out directly to entail our knowing them!
I think it has been implicitly assumed that we know them. One of my problems with Bruno's
argument is that it appears to me that his idealized model of knowledge, []p & p, implies
that every provable proposition is known.
If this is indeed the case it would surely settle the matter of the "platonic" existence
of mathematics in the most astonishing (but satisfactory) manner.
It's not lost on me, by the way, that my "strict" account of physicalism could still lay
claim, prima facie, to an analogous a posteriori epistemic justification in terms of a
conscious knower. It's just that - on the assumption of *strict* material reductionism -
the further supervention of computation on physical tokens could play no role in the
explanation.
David
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