On 2/21/07, Jesse Mazer <lasermazer.domain.name.hidden> wrote:
>
>
> Stathis Papaioannou wrote:
> >
> >On 2/20/07, Jesse Mazer <lasermazer.domain.name.hidden> wrote:
> > >
> > >
> > > >I would bet on functionalism as the correct theory of mind for
> various
> > > >reasons, but I don't see that there is anything illogical the
> >possibility
> > > >that consciousness is substrate-dependent. Let's say that when you
> rub
> > > two
> > > >carbon atoms together they have a scratchy experience, whereas when
> you
> > > rub
> > > >two silicon atoms together they have a squirmy experience. This could
> > > just
> > > >be a mundane fact about the universe, no more mysterious than any
> other
> > > >basic physical fact. What is illogical, however, is the "no causal
> > > effect"
> > > >criterion if this is called epiphenomenalism. If the effect is purely
> >and
> > > >necessarily on first person experience, it's no less an effect; we
> >might
> > > >not
> > > >notice if the carbon atoms were zombified, but the carbon atoms would
> > > >certainly notice. I think it all comes down to the deep-seated and
> very
> > > >obviously wrong idea that only third person empirical data is genuine
> > > >empirical data. It is a legitimate concern of science that data
> should
> >be
> > > >verifiable and experiments repeatable, but it's taking it a bit far
> to
> > > >conclude from this that we are therefore all zombies.
> > > >
> > > >Stathis Papaioannou
> > >
> > > One major argument against the idea that qualia and/or consciousness
> >could
> > > be substrate-dependent is what philosopher David Chalmers refers to as
> >the
> > > "dancing qualia" and "fading qualia" arguments, which you can read
> more
> > > about at http://consc.net/papers/qualia.html . As a
> thought-experiment,
> > > imagine gradually replacing neurons in my brain with functionally
> > > identical
> > > devices whose physical construction was quite different from neurons
> > > (silicon chips emulating the input and output of the neurons they
> > > replaced,
> > > perhaps). If one believes that this substrate is associated with
> either
> > > different qualia or absent qualia, then as one gradually replaces more
> >and
> > > more of my brain, they'll either have to be a sudden discontinuous
> >change
> > > (and it seems implausible that the replacement of a single neuron
> would
> > > cause such a radical change) or else a gradual shift or fade-out of
> the
> > > qualia my brain experiences...but if I were noticing such a shift or
> > > fade-out, I would expect to be able to comment on it, and yet the
> > > assumption
> > > that the new parts are functionally identical means my behavior should
> >be
> > > indistinguishable from what it would be if my neurons were left alone.
> >And
> > > if we suppose that I might be having panicked thoughts about a change
> in
> > > my
> > > perceptions yet find that my voice and body are acting as if nothing
> is
> > > wrong, and there is no neural activity associated with these panicked
> > > thoughts, then there would have to be a radical disconnect between
> > > subjective experiences and physical activity in my brain, which would
> > > contradict the assumption of supervenience (see
> > > http://philosophy.uwaterloo.ca/MindDict/supervenience.html ) and lead
> to
> > > the
> > > possibility of radical mind/body disconnects like rocks and trees
> having
> > > complex thoughts and experiences that have nothing to do with any
> >physical
> > > activity within them.
> > >
> > > Jesse
> >
> >
> > It's a persuasive argument, but I can think of a mechanism whereby your
> >qualia can fade away and you wouldn't notice. In some cases of cortical
> >blindness, in which the visual cortex is damaged but the rest of the
> visual
> >pathways intact, patients insist that they are not blind and come up with
> >explanations as to why they fall over and walk into things, eg. they
> accuse
> >people of putting obstacles in their way while their back is turned. This
> >isn't just denial because it is specific to cortical lesions, not
> blindness
> >due to other reasons. If these patients had advanced cyborg implants they
> >could presumably convince the world, and be convinced themselves, that
> >their
> >visual perception had not suffered when in fact they can't see a thing.
> >Perhaps gradual cyborgisation of the brain as per Hans Moravec would lead
> >to
> >a similar, gradual fading of thoughts and perceptions; the external
> >observer
> >would not notice any change and the subject would not notice any change
> >either, until he was dead, replaced by a zombie.
> >
> >Stathis Papaioannou
>
> That's an interesting analogy, but it seems to me there's an important
> difference between this real case and the hypothetical fading qualia case
> since presumably the brain activity associated with inventing false visual
> sensations is different from the activity associated with visual
> sensations
> that are based on actual signals from the optic nerve. Additionally, we'd
> still assume it's true that their reports of what they are seeing match
> the
> visual qualia they are having, even if these visual qualia have no
> relation
> to the outside world as in dreams or hallucinations. In the case of
> replacing the visual cortex with functionally identical computer chips,
> the
> activity in the remainder of the brain would be identical to what it would
> be if the visual cortex were left intact, and if the "fading qualia"
> picture
> were true they'd be continuing to report visual sensations even when they
> weren't having any whatsoever, not even hallucinatory ones. So basically
> you'd be forced to conclude that even in normal people with unmodified
> brains, the fact that we talk about having various sensations and
> perceptions has absolutely nothing to do with the fact that we actually do
> have them. Of course anyone who sees qualia as "epiphenomal", and who sees
> physically identical zombies as a logical possibility, will say that our
> qualia don't have any *causal* effect on the physical brain, but they
> still
> usually assume some set of "psychophysical laws" which insure that the
> association between physical activity in the brain and qualia is a
> sensible
> one (somewhat akin to Leibniz's 'pre-established harmony' solution to the
> mind-body problem--see
> http://en.wikipedia.org/wiki/Pre-established_harmony
> ), so that the causal relation between the brain processing visual
> information and the brain creating verbal descriptions of what one is
> seeing
> is mirrored by a relation between visual qualia and the qualia associated
> with verbal thoughts about what one is seeing. If you don't assume such
> "sensible" psychophysical laws, then you have no basis for believing even
> now that you should trust any verbal thoughts about what you are seeing. I
> might say to myself that I can trust my visual experiences themselves
> before
> I translate them into verbal terms, but the very act of *saying* that to
> myself seems to undermine it since I can't be sure if the words 'visual
> experiences' even refer to anything--a bizarre paradoxical situation.
>
> Jesse
It is a complicated issue. Patients with psychotic illnesses can sometimes
reflect on a past episode and see that they were unwell then even though
they insisted they were not at the time. They then might say something like,
"I don't know I'm unwell when I'm unwell, but when I'm well I know I'm
well". OK, but then how do you know that you're not unwell now? How do I
know I'm not unwell now? We rely on other people telling us (although of
course we won't believe them if we lack insight into our own illness), but
in the example of fading qualia we would (a) not notice that the qualia were
fading, a kind of delusion or anosognosia, and (b) no-one else would notice
either, because by whatever mechanism the external appearance of conscious
behaviour would be kept up. So how do I know I'm not that special kind of
zombie or partial zombie now? I feel absolutely sure that I am not but then
I would think that, wouldn't I? The fact is, it happens all the time, to at
least 1% of the population.
Stathis Papaioannou
Stathis Papaioannou
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Received on Tue Feb 20 2007 - 21:01:23 PST