Dembski, Decoherence and the brain
By Ian Musgrave
Posted July 19, 2005
Over at Dembski's blog you will find him commenting on
My good friend and colleague Jeffrey Schwartz (along with Mario Beauregard
and Henry Stapp) has just published a paper in the Philosophical Transactions
of the Royal Society that challenges the materialism endemic to so much of
contemporary neuroscience. By contrast, it argues for the irreducibility of
mind (and therefore intelligence) to material mechanisms.
Unfortunately for Dembski, this is completely wrong. The paper, "Quantum physics in neuroscience and psychology: a neurophysical
model of mind-brain interaction" Jeffrey M. Schwartz, Henry P. Stapp, Mario
Beauregard, Philosophical Transactions: Biological Sciences, 2005 argues for
a quantum mechanical approach to the problem of mind-brain interaction. Quantum
mechanics may seem really weird to the non-physicist, and involve things
like "spooky action at a distance" but quantum mechanics is part of
the material world in the sense that both scientists use it and Schwartz et al.,
are using the this paper .
...brain is made up entirely of material particles and fields, and
that all causal mechanisms relevant to neuroscience can therefore be
formulated solely in terms of properties of these elements. (Emphasis
An electron is no less material in quantum mechanics for it being described
as a probability distribution. What Schwartz et al. are arguing for is a
non-mechanistic description (in the classical physics sense) of mind-brain
interaction, not a non-materialist one (in Dembski's sense). Furthermore, it is
not "irreducible" in Dembski's sense either.
Now, a few caveats. Firstly, I'm a neuropharmacologist, I grow pretend nerve
cells in dishes and try to unravel the molecular basis of nerve function and
survival. So I'm at the "reductionist" end of the neuroscience spectrum (and the
Paleyists have a thing about reductionism) and my comments on psychology are
those of an interested lay-person. On the other hand I've spent a lot of my
professional career working on neuronal calcium channels in one way or another,
so when I talk about ion channels, it's in a professional capacity. Secondly,
the mind-body problem is hard; really, really hard. And there have been no end
of books by eminent philosophers and neuroscientists on it (see the end of this
post for some suggested reading). We are far from understanding the biological
basis of consciousness, and it is one
of the top 25 questions in the journal Science's 125th anniversary
However, there is a general consensus that the "mind"  is intimately
associated with the brain. Brain damage affects the mind. Stroke can affect
personality, the ability to associate words with images. Brain tumours can
induce extreme personality changes that are reversed when the tumour is removed.
A wide variety of drugs, acting solely on brain structures, influence our minds. What is contentious is whether the "mind"
is solely generated by the brain (either directly or emergently), or whether
"mind" exists in some sense separately from the brain. Also, how can the "mind"
influence the brain if it is a construct of the brain?
The latter seems to be the starting point of Schwartz et al. They observe
that people can be trained to regulate their emotions or overcome phobias.
"Change the mind and you change the brain" is the title of a paper from one of the authors. One of their claims
seems to be that as "mental effort" is experiential and cannot be described
exclusively in material terms, we cannot use "classical physical" explanations
to describe how "mind" can change the brain. Thus they turn to quantum
mechanics. This is not new; Roger Penrose articulated a quantum mechanical view
of consciousness some time ago. However they have looked at a quantum mechanical
description of brain action in more depth than Penrose did.
I have two issues with their approach. Firstly, there is no need for some new
principle to describe what happens when people learn to overcome social phobias.
The key is that it is learning. We have known for a long time that learning
changes brain structure. Nerve firing rates are changed through use
dependent changes in nerve chemistry, new connections between nerves are forged
and existing ones re-enforced. New firing circuits are produced. This happens in
all learning, from unconscious learning of motor skills to conscious learning of
more complicated cognitive tasks. Directed attention of the sort
used in the phobia paper is also seen in non-human primates as well: it is not only a human domain.
Interestingly, there is a type of mental retardation associated with fragile X syndrome that involves "executive attention", one of
the processes Schwartz et al. talk about. A single gene disorder, it causes
these people's brains to be normal macroscopically, but with fewer
nerve connections than normal. Learning has a basis in remodeling the brain.
Learning in stroke patients can produce new nerve pathways to replace the
damaged ones and restore some degree of function. This doesn't require quantum
mechanics to explain, so why should learning which circumvents phobias be any
different to learning that circumvents stroke damage? And it is learning. In the
spider phobia paper, people are repeatedly exposed to spiders in an environment
where they learn that spiders can't harm them. The title of the paper should
have been "Change the brain and you change the mind".
Secondly, the way they describe the quantum mechanical processes in the brain
is problematic. For nerve cells to fire, calcium must
enter the nerve cell in response to a stimulus. They correctly state that
the ion channels that let calcium into nerve cells are very narrow (0.086-0.158
nm). They claim this will result in a calcium ion to be laterally confined, so
that its velocity must become large by the quantum uncertainty principle, a
cloud of probability spreads out from the ion channel. The spreading of the ion
wavepacket means that it may or may not interact with the calcium-binding
proteins that will result in neurotransmitter release, which will mean that the
nerve may or may not fire and so on until the brain is one mass of probability
and requires a quantum process to collapse it.
There are a number of problems with this. Firstly, lots of excitable tissues
have narrow calcium channels and multiple connections. Exactly the same process
occurs in the heart, where clouds of ions spread out from a calcium channel
until a large mass of cells are firing, the same goes with blood vessels. We
need no appeal to quantum mechanics to understand the heart beat, so why is the
brain in principle any different (the brain will have more quantum superimposed
states, but the heart will have several billion as well). Schwartz et al. claim
there is a minimum complexity where quantum effects will begin to dominate, but
don't provide an indication of what this minimum size is. We can have a stab at
it by looking at the minimum brain size in a conscious organism. New
Caledonian Crows are tool makers and users. When presented with a unique
problem, they can create a new tool to help them solve it. By all definitions of
the word consciousness, New Caledonian Crows are conscious entities like chimps
Yet they have a brain the size of a walnut. So Schwartz et al.'s quantum
processes must take place at these levels of cell number and connectivity. This
means that the quantum mechanical processes do occur in the heart if Schwartz et
al's interpretation is right. They will also occur in the enteric
nervous system, a thick layer of nerves that lie between two muscle layers
in the gut. Highly branching and interconnected, the enteric nervous system has
been termed a "second brain". The quantum processes that underlie Schawrtz et
al.'s model of mind-brain interaction must underlie enteric nervous system-gut
The other implication is that these processes are not confined to humans
(pace the New Caledonian Crows above), and must apply to monkeys,
marmosets and mollusks. So the quantum mechanical processes cannot be an
"irreducible" barrier between humans and animals, as Dembski hopes. Furthermore,
it is not "irreducible" in Dembski's sense. In Schwartz et al.'s model, the
conscious mind-brain interaction is an emergent property that occurs when the
number of connections are high enough for quantum properties to dominate.
Biologists are perfectly happy with emergent phenomena, and connectivity-related
emergence has been suggested to explain brain phenomena before.
Finally there is the problem of quantum
decoherence. Schwatz et al. largely dismiss it.
The brain matter is warm and wet and is continually interacting intensely
with its environment. It might be thought that the strong quantum decoherence
effects associated with these conditions would wash out all quantum effects,
beyond localized chemical processes that can be conceived to be imbedded in an
essentially classic world. Strong decoherence effects are certainly present,
but they are automatically taken into account in the von Neumann formulation
employed here. ....
I think the decoherence effects are a lot stronger than they suspect. A
calcium ion has to run the gauntlet of many, many molecules before it reaches a
binding site, it repeatedly bounces off water molecules and protein molecules.
If there is any meaningful quantum effects left by the time calcium binds to
synaptogamin, I'd be very surprised. I've measured calcium transients in nerve
cells (and so have many other people), the spread of the calcium in the nerve
terminal is at the standard diffusion rate, so it looks like the quantum effects
have been largely removed (allowing of course for the fact that we are observing
these systems, which collapses their quantum properties). Also, Schwartz et al.
talk of a single ion channel and a single calcium ion and a single calcium
binding target. But in realty in a single nerve terminal, there are many ion
channels that will be activated, letting in many calcium ions (typical nerve
terminal concentrations of calcium during a nerve impulse is around 100 nM),
which will bind to many binding sites. The statistical effects of these many
interacting calcium ions should wipe out any quantum indeterminacy.
There are many aspects of this paper that don't seem to hang together for me
outside of the issues outlined above. However, I must emphasize again that I am
a neuropharmacologist, not a physicist (I don't even play one on TV). Even
though I have forced my way to the end of both "The Emperors New Mind" and
"Shadows of the Mind" my grasp of quantum mechanics remains very basic.
But the main issue is that, even if Schwartz et al. are completely correct,
this is still a physical theory, and is still "materialist" in the sense that
scientists use the word.
- 1) Schwartz et al.'s model is a materialistic model; it uses
a quantum mechanical rather than a classical approach, but it is no less
materialistic for that.
- 2) Schwartz et al.'s model applies to all large
concentrations of interacting, excitable cells, not just conscious brains.
Consciousness is not unique in this model.
- 3) Schwartz et al.'s model applies
to conscious non-humans. It provides no distinguishing barrier between humans
- 4) Schwartz et al.'s model is not "irreducible" in Dembski's
sense, it is a version of emergence.
- 5) It is not clear if Schwartz et al's
model is really needed to explain the phenomena they need to explain.
 It needs to be noted that there are several different interpretations of
Quantum Mechanics. The most familiar will be the "many worlds"
interpretation. Another common one is a Bayesian
statistical approach. The interpretation used in this paper is Stapp's own,
and is not very widespread.
The Skeptic's Dictionary entry on Mind
Blackmore, Susan. Consciousness: An Introduction (Oxford
University Press 2003).
Dennett, Daniel Clement. Consciousness explained illustrated by
Paul Weiner (Boston: Little, Brown and Co., 1991).
Roger, The Emperor's New Mind: Concerning Computers, Minds and the Laws of
Physics, (Oxford Paperbacks. 1997)
Acknowledgements: Many thanks to the Panda's Thumb crew for help
discussion, particularly Erik for helping me with some Quantum Mechanical
Originally posted at The Panda's Thumb.