Greg Detre
Thursday, 22 February, 2001
Where/who?
three worlds + three mysteries: from physical � mental � platonic � physical
physical world � matter, external
mental world � experiential content, consciousness
platonic world � mathematical truths that underly the world as we know it
each seems to depend on the world that precedes it
seems that we can�t be creating the whole world from our mentality because of the circularity of the structure/relations
the diagram is intended to illustrate the paradoxicality of the whole thing
it might be that the different worlds extend in ways beyond their relations with each other, e.g. parts of the mental world that extend beyond the physical
but Penrose suspects that this isn�t the case
there are many things in maths that are non-computable
the computable forms a subset of the platonic world, and we can still access it from the mental world, but it might or might not cover all of the physical world
Penrose thinks that there are parts of the physical world (e.g. that which is responsible for our conscious mentality) that is outside the scope of the computable
points of view about the relationship between consciousness + computation
whatever thinking is, it�s basically computation
consciousness/qualia as the passive aspect, FW as
the active aspect???
if a computer were to perform the right computations, its awareness would somehow spring into being
awareness = a feature of the brain�s physical actions, and computational simulation cannot alone reproduce this
so there�s something inherent in the physical instantiation of the brain, for instance, that gives rise to consciousness, different to computation
a simulation of the brain does not itself feel anything (e.g. Chinese room)
what might it possibly be that is physical but non-computational???
Penrose supports C
Penrose is more interested in understanding than qualia or FW
can a computer be capable of general understanding
unsure what the words understanding, intelligence or awareness mean
but we can talk about their relations to each other
cannot talk about intelligence without understanding
and if it has understanding, then it must have awareness
[NO]
example of chess game with white barrier of pawns and king behind, where all you have to do to draw is aimlessly move the king without moving the pawns, whereas Deep Thought attacked the rook in an effort to improve its evaluation of the game (David Norwood + William Hartson)
this is intended to show that humans have understanding�
Chinese room
huge set of instructions for manipulating Chinese characters whose output appears to demonstrate understanding
it doesn�t matter whether you think it�s a good argument, so much as which of the accounts it targets
it basically says that (A) is wrong
Turing test
interrogator is supposed to be able to infer which is the human and which is the computer
does the Turing test actually establish the presence/absence of consciousness? is consciousness something that you can discern through questioning? does it show itself externally?
yes: A + C
no: B + D
another argument from Chalmers: replacing the neurons one by one with functionally identical transistors
according to Chalmers, consciousness would remain
this only really argues against (B)
this would not really work for Penrose�s position (C), since keeping the computation the theory the same is not what gives rise to consciousness
�
C + D both survive Searle�s and Chalmers� arguments
Penrose prefers C: otherwise, why would consciousness have evolved?
G��s incompleteness theorem
something non-computational - where should one draw the line?
mathematical understanding
human understanding generally
human consciousness
animal consciousness
polyominoes � can you tile a plane with one or more of these shapes?
3 shapes � can cover the entire plane, but never copies itself
but surely there are a finite number of combinations???
can�t have a general program that could answer the question for any 3 shapes
quantum level (no indeterminacy) � measurement (quantum
state reduction, non-determinstic, time-asymmetric, non-local, e.g. geiger
counter) �
classical level
at the quantum level, Schr�ger�s equation gives computability
we will never know them as anything other than indeterminate
it�s at the measurement level that all the randomness/indeterminacy occurs (so the indeterminacy is epistemological, on this understanding, rather than ontological, i.e. at the quantum level)
yet if that is the case, then why does the measurement which is based on the determinate quantum level, where does the randomness come from
so our current understanding of quantum mechanics is incomplete
need new object reduction, to which the quantum and classical levels are approximations
microtubules: borderline between quantum + classical level
ideas about single-celled organisms are from Hameroff (e.g. paramecium, amoeba) � the cytoskeleton contains the microtubules�
there are activities going on at the quantum level, in the microtubules, which have to influence the synapse strengths
so ultimately the quantum adds a new level of uncomputable computation to the brain
Turing test vs zombies
fading + dancing qualia
what sort of physical non-compuational action of the brain could one be talking about???
well, clearly quantum microtubules blah blah
does massive parallelism sort of make the question of computability irrelevant???
no, because it�s about computation, rather than difficulty
aren�t there microtubules in all cells???
are you talking about the hard problem, i.e. how qualia arise???
or is this purely about FW???
how/what do microtubules help???
is it about the uncomputable Godel-incomplete problems that the brain is able to approach???
resolution of the problem of indeterminacy in measurement is going to explain concsiousness, so we need a new component of quantum mechanics � we need it anyway. how do we know it�s unattainable???
he�s simply being optimistic. if it was to prove wholly unattainable, that would change things.
what�s your level of certainty � ???
randomness doesn�t help with FW
yes, of course not, but what if the
randomness is only random-seeming
one objection to Penrose�s Godel argument is that it doesn�t allow for the fact that we make mistakes
tries to discuss the possibility of mistakes in Shadows of the Mind
Turing considers that the way that we can escape Godel�s confines is by making mistakes
what about a physical law of information??? platonic � physical worlds�???
how do microtubules help???
Hameroff�s ideas are very different to Penrose�s
for instance, amoeba seem to be able to do things without a NS, and we don�t know how � so the microtubules might be implicated
Duggins experiment with binding problem of motion and colour (Bell�s inequalities) (Zeki et al)
see whether people form one impression or the other
what about Strawson�s opinion, that penrose�s hidden agenda is FW???
not really addressing the determinism issue, because it�s more about non-computability
doesn�t know how it will affect FW
the idea that FW can be explained in terms of electrons �choosing� one state or the other is more Eccles� than Penrose�s � it�s wrong � the electrons themselves are determined, the indeterminacy lies in the measurement (see above)
Chalmers thinks that your theory doesn�t help at all with what you call the �passive� aspect of consciousness, any more than a computable process would, since it really doesn�t address how or why qualia arise from quantum effects
could the �microtubules giving rise to consciousness� idea be sort of like Egan�s idea of a mind spread across quantum worlds, that is only a sliver within a single world