I can't speak for other quantum-mind theorists when
it comes to specifics. But this is my model.
1. The world consists of interacting 'quantum monads'
which are like the substances of classical metaphysics
in being enduring units, but possessing states whose
complexity (number of degrees of freedom, descriptive
bit complexity) is variable. What we call 'two entangled
particles' is actually a single quantum monad with
twice as many degrees of freedom as a single particle.
2. The individual self is a single quantum monad
in a very complex state. A momentary state of
consciousness is a momentary state of the monad that
is you. Physically this seems to require macroscopic
quantum states in the brain which are relevant to
cognition, so this is a hypothesis with empirical
consequences.
3. The ontology of current natural science (space,
time, quantity, causality, and not much else) is
incomplete. Current fundamental theories make use of
some but not all of the ontological variety already
apparent to us in experience, and philosophy of mind
then attempts to reduce the remaining variety
(qualia, intentionality, simultaneity) to some
combination of the naturalistic categories.
Instead, physical theory needs to be reformulated so
it has the necessary ontological diversity built in.
4. Only a quantum monad can 'have a self', think,
be aware. Classical computers consist of large numbers
of quantum monads marshalled in predictable ways,
and can formally imitate the state dynamics of a monad,
but cannot experience or think. In particular, the
representational content of computational states is
just like the semantic content of words on a page -
a matter of convention and interpretation - whereas
the natural intentional states of monads have intrinsic
intentionality.
5. On the other hand, a quantum computer at least
has the potential for mentality, because (by hypothesis)
quantum-coherent systems are actually monads. But the
actual content of a quantum computer's experience would
not need to be the content of the computations we have
it perform - there would only need to be an isomorphism
between them.
I already said some of this in a talk at
http://www.u.arizona.edu/~mjporter/tucson/01.html
(click on the transparencies to proceed through them).
Having said that, I can now make some responses.
Ben Goertzel said he thinks that
>2) The ~mind~ is a nonphysical entity -- a pattern of organization of
>patterns -- and is not intrinsically tied to any particular set of physical
>laws
As I've just said, I believe implementation matters, and
that 'pattern' is still too formal a notion to be the
whole story - it doesn't have enough 'subjective ontology'
in it.
James Rogers said
>As a general question, what part of the mind would seem to require quantum
>machinery?
The unity of consciousness, which I propose to identify as
the experience from within of an ontological unity which
we detect from without as quantum entanglement.
Let me say in passing that I don't deny that selves are
(in a sense) composite and variable, and that false beliefs
about personal constancy are certainly possible. It's just
that any first-person demonstrations that the self has parts
will remain within some ontology of the subjective - they
will break it down into drives or personalities or sensory
modalities... - nothing like elementary particles, which
result from reductionism applied in the third person; and
the phenomenon of entanglement shows that we even have
third-person evidence that the 'corpuscular' ontology is
not the full story.
Anders Sandberg said
>I don't see how quantum mechanical mechanisms would introduce anything
>ontologically new in a description of mind. Entanglement is very neat,
>but such correlations could just as well be implemented in a contrived
>classical way, so why would quantum mechanics add any new here?
Quantum mechanics in itself doesn't add the ontological
novelty I need, but it has room for it.
Ken Clements said... a lot:
>you need to tell us more about what you are calling "mind" so we have
>some way of generating falsifiable predictions about it. You also talk
>about "thoughts" without a bright line test that would say what kind of
>behavior is thought vs something like reflex. Also, where on the
>evolutional continuum is the bright line where creatures got minds and
>started having thoughts? When in your own personal development from a
>single cell did you get a "mind" and have "thoughts"?
If intentionality is the defining feature of the mental,
and intentionality can only be a property of 'quantum unities',
then there's no first-principle *behavioral* criterion for the
presence of thought; what you need to know is whether the
alleged thinking system is in a quantum-coherent state.
One shouldn't adopt this criterion until one has reason to
believe that some quantum theory of mind is correct, of course.
More to the point, ordinary empiricism is not much good for
formulating basic concepts of mind, because it already presupposes
that you're an observer having experiences. There seems to be
no alternative to introspection and philosophy at this point;
you just have to dive into the circle of phenomenology,
epistemology, and ontology, and hope you come back with something
comprehensible. In the longer run one would hope that a fully
fleshed out theory of mind would cast light on what was going
on in such investigations, in a way that would render them more
secure - but it's not at all easy. Looking for quantum coherence
in living matter seems comparatively straightforward.
I'll decline to speculate on where the dividing line between
mindless and mindful might lie in evolutionary and individual
development, but certainly my whole program of taking mind
seriously implies that such transitions objectively occur.
>One very hard thing for me to buy in the Quantum Mind speculation is
>that somehow the quantum coherence involved is not impacted by the
>strong magnetic fields used to image living chemistry in an MRI
>equipment. Small frogs have been magnetically levitated by very high
>fields (http://www.sci.kun.nl/hfml/froglev.html) without loss of neural
>activity. Humans have remained conscious through exposure to lethal
>levels of ionizing radiation that interacts directly to introduce
>disorder on the quantum level. However, micrograms of LSD can
>restructure your consciousness through straightforward chemical paths.
This is a good point. But have psychologists studied people
undergoing MRI? And it's not just a matter of MRI destroying
quantum coherence; MRI can *induce* transient quantum coherence.
So if these quantum brain states are there, the first question
is whether they're affected by MRI, the second question is
whether they're affected enough for the changes to be behaviorally,
instrumentally, or phenomenologically detectable.
As for LSD - the quantum side of the brain, if it exists, is not
some wholly separate sphere. It's going to consist of bose-condensed
phonons in protein microfilaments, or entangled electrons in
microtubules, or some similarly concrete thing that's quite
accessible to influence by the introduction of a nanomole of LSD
molecules. And there's no straightforward chemical path leading
from 'LSD' to 'new structure of consciousness' because there's
no existing chemical description of the latter.
>Brain imaging technology now lets us watch neural activity as people
>process information. Your "mind" may look like one unfathomable whole
>from the inside, but people's brain activity looks more and more
>mechanistic when view by researchers from the outside. We know that a
>specific brain structure is responsible for generating the "self." If
>this is damaged, you may still be able to answer questions on an IQ
>test, but 'you' are gone.
What brain structure is that? What is *demonstrably* gone in
these 'selfless' people - self-knowledge, self-preservation?
To be a self, in the sense of being a locus of experience,
does not logically require either of these.
On my view, the conscious brain is not a homogeneous quantum glob.
It's more like a hive of classical neural coprocessors which
interface between a distributed quantum entity and its environment.
But we may already have observed the quantum brain in action.
Quantum correlations, amplified by classical processes, might be
responsible for some already-known forms of synchronized neural
activity.
>As for the limitations of computer science re explaining thinking,
>please remember that throughout history science could not explain
>things, until it could. Consider how much the last 50 years of genetics
>have explained. We are just getting to the point of being able to
>understand how flat worms work. Do you expect we are going to go
>marching up the chain of phylogeny and suddenly hit a snag because the
>models do not include quantum computing?
Well, I already expressed my skepticism about the ability of
*computer* science to be a foundation for the science of mind...
How would you answer the three problems for a computational
theory of intentionality which I listed in my original message?
And if we are only just getting to the point of understanding
how flatworms work, there's still time for quantum phenomena to
show up even there.
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