On Mon, Sep 5, 2011 at 4:05 PM, Craig Weinberg <whatsons...@gmail.com> wrote:

>> Nothing really new has turned up in the physics underlying the brain
>> in over a century,
>
> I'm assuming you're just being thoughtlessly condescending here and
> not actually saying that physics has not changed in 100 years, or that
> the brain has some separate physics that anything else. You're not
> telling me that MRIs don't count as something new, or that quantum
> theories of consciousness are not the result of recent interpretations
> of physics.

Many discoveries have of course been made in neuroscience in the past
hundred years, eg. mapping brain function and working out its
neuropharmacology, but all these discoveries are consistent with
old-fashioned chemistry. This is in contrast to advances in astronomy,
for example. It isn't possible to explain how the sun shines without
nuclear physics.

>> a subject reasonably well-understood even in the
>> nineteenth century. However, it is possible that something
>> fundamentally novel will turn up at some future point.
>
> That's a strawman of scientific innovation. It wasn't that General
> Relativity 'turned up' at some point, or that it came to Einsteins
> attention because of some new kind substance that defied Newtonian
> mechanics - it was just his making a newer, greater sense out of
> existing perceptions.

General Relativity was something new and it made predictions that
differed from those of classical mechanics. Roger Penrose believes
that quantum gravity is important in brain function and that when the
theory of quantum gravity is eventually discovered it will be found to
be not computable, which is why he thinks computers will forever be
incapable of brainlike intelligence. As it stands, this idea is not
self-contradictory, but there is no good evidence in its support.

>>In that case,
>> the brain will still follow the laws of physics, just laws that we
>> previously didn't know about.
>
> Right. Sensorimotive interiority is what those laws will look like.

That doesn't sound like a physical law, being a rule describing how
matter or energy will behave in a particular situation. A true theory
of consciousness will, if consciousness affects behaviour, describe
how it will cause ion channels to open where chemistry predicts they
will remain closed. And even short of actually discovering these laws,
it should be obvious that ion channels are in fact opening contrary to
the laws already known.

>> The brain's behaviour will still be
>> computable and therefore the brain's consciousness will still be
>> computable if the new laws are computable.
>
> Some aspects of the brain's behaviors are computable, but others never
> have been and maybe cannot be.
>
>>If the new laws are not
>> computable it might still be possible to make artificial brain
>> components using non-computational devices, and consciousness would
>> still be preserved.
>
> I agree. I think it will likely have to be more based upon tissue
> replication than logical emulation is all.

We would have to work out what the non-computable component of the
cell is and replicate it. Are real numbers required for consciousness?
We might then need an analogue computer. Is quantum randomness
important? Then put an unstable radioisotope into the artificial
neuron. Are there tiny black holes in the microtubules? Then find out
a way to make and insert tiny black holes.

>> In a sense it is true that particle physics does not explain human
>> experience, and this is what Chalmers called the "Hard Problem" of
>> consciousness. It does not just apply to known physics, it applies to
>> any naturalistic theory of consciousness. If we show that the brain
>> contains dark matter, and the dark matter is responsible for
>> consciousness, it is still possible to say, "But when I see dark
>> matter, I don't see thoughts and feelings". And you can make that
>> observation in response to any theory at all.
>
> That's why we have to have a theory which lets consciousness be what
> it is and not have to be described in terms which are completely
> foreign to it. Consciousness is experience. Perception, pattern
> recognition, sensation, thought, feeling... That's what it is, that's
> what it does, and that's what it's made of. You can correlate them to
> external physical patterns, and you can understand their precise
> relation, and you can use one to drive the other, but you can't make
> the interior of one thing be the exactly same as the exterior of
> something else. Something that feels like we do is probably going to
> be a lot like we are.

It doesn't really explain consciousness to say it is fundamental to
matter or fundamental to function and I don't see why one should a
priori be preferred over the other as an explanation.


-- 
Stathis Papaioannou

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