[THS] Ray Tallis: You won`t find consciousness in the brain

[Peter Webster]

http://www.newscientist.com/article/mg20527427.100-you-wont-find-consciousness-in-the-brain.html?full=true&print=true

You won't find consciousness in the brain

    * 07 January 2010 by Ray Tallis
    * Magazine issue 2742. Subscribe and get 4 free issues.
    * For similar stories, visit the The Big Idea and The Human Brain Topic Guides

Consciousness in action? It is tempting to think that's what is going on - but wrong
(Image: Hans Neleman/Getty)


MOST neuroscientists, philosophers of the mind and science journalists feel the time
is near when we will be able to explain the mystery of human consciousness in terms
of the activity of the brain. There is, however, a vocal minority of neurosceptics who
contest this orthodoxy. Among them are those who focus on claims neuroscience
makes about the preciseness of correlations between indirectly observed neural
activity and different mental functions, states or experiences.

This was well captured in a 2009 article in Perspectives on Psychological Science by
Harold Pashler from the University of California, San Diego, and colleagues, that
argued: "...these correlations are higher than should be expected given the
(evidently limited) reliability of both fMRI and personality measures. The high
correlations are all the more puzzling because method sections rarely contain much
detail about how the correlations were obtained."

Believers will counter that this is irrelevant: as our means of capturing and analysing
neural activity become more powerful, so we will be able to make more precise
correlations between the quantity, pattern and location of neural activity and aspects
of consciousness.

This may well happen, but my argument is not about technical, probably temporary,
limitations. It is about the deep philosophical confusion embedded in the assumption
that if you can correlate neural activity with consciousness, then you have
demonstrated they are one and the same thing, and that a physical science such as
neurophysiology is able to show what consciousness truly is.

Many neurosceptics have argued that neural activity is nothing like experience, and
that the least one might expect if A and B are the same is that they be
indistinguishable from each other. Countering that objection by claiming that, say,
activity in the occipital cortex and the sensation of light are two aspects of the same
thing does not hold up because the existence of "aspects" depends on the prior
existence of consciousness and cannot be used to explain the relationship between
neural activity and consciousness.

This disposes of the famous claim by John Searle, Slusser Professor of Philosophy at
the University of California, Berkeley: that neural activity and conscious experience
stand in the same relationship as molecules of H2O to water, with its properties of
wetness, coldness, shininess and so on. The analogy fails as the level at which water
can be seen as molecules, on the one hand, and as wet, shiny, cold stuff on the
other, are intended to correspond to different "levels" at which we are conscious of
it. But the existence of levels of experience or of description presupposes
consciousness. Water does not intrinsically have these levels.

We cannot therefore conclude that when we see what seem to be neural correlates
of consciousness that we are seeing consciousness itself. While neural activity of a
certain kind is a necessary condition for every manifestation of consciousness, from
the lightest sensation to the most exquisitely constructed sense of self, it is neither a
sufficient condition of it, nor, still less, is it identical with it. If it were identical, then
we would be left with the insuperable problem of explaining how intracranial nerve
impulses, which are material events, could "reach out" to extracranial objects in order
to be "of" or "about" them. Straightforward physical causation explains how light
from an object brings about events in the occipital cortex. No such explanation is
available as to how those neural events are "about" the physical object. Biophysical
science explains how the light gets in but not how the gaze looks out.

Many features of ordinary consciousness also resist neurological explanation. Take the
unity of consciousness. I can relate things I experience at a given time (the pressure
of the seat on my bottom, the sound of traffic, my thoughts) to one another as
elements of a single moment. Researchers have attempted to explain this unity,
invoking quantum coherence (the cytoskeletal micro-tubules of Stuart Hameroff at
the University of Arizona, and Roger Penrose at the University of Oxford),
electromagnetic fields (Johnjoe McFadden, University of Surrey), or rhythmic
discharges in the brain (the late Francis Crick).

These fail because they assume that an objective unity or uniformity of nerve
impulses would be subjectively available, which, of course, it won't be. Even less
would this explain the unification of entities that are, at the same time, experienced
as distinct. My sensory field is a many-layered whole that also maintains its
multiplicity. There is nothing in the convergence or coherence of neural pathways
that gives us this "merging without mushing", this ability to see things as both whole
and separate.

And there is an insuperable problem with a sense of past and future. Take memory.
It is typically seen as being "stored" as the effects of experience which leave
enduring changes in, for example, the properties of synapses and consequently in
circuitry in the nervous system. But when I "remember", I explicitly reach out of the
present to something that is explicitly past. A synapse, being a physical structure,
does not have anything other than its present state. It does not, as you and I do,
reach temporally upstream from the effects of experience to the experience that
brought about the effects. In other words, the sense of the past cannot exist in a
physical system. This is consistent with the fact that the physics of time does not
allow for tenses: Einstein called the distinction between past, present and future a
"stubbornly persistent illusion".

There are also problems with notions of the self, with the initiation of action, and with
free will. Some neurophilosophers deal with these by denying their existence, but an
account of consciousness that cannot find a basis for voluntary activity or the sense of
self should conclude not that these things are unreal but that neuroscience provides
at the very least an incomplete explanation of consciousness.

I believe there is a fundamental, but not obvious, reason why that explanation will
always remain incomplete - or unrealisable. This concerns the disjunction between
the objects of science and the contents of consciousness. Science begins when we
escape our subjective, first-person experiences into objective measurement, and
reach towards a vantage point the philosopher Thomas Nagel called "the view from
nowhere". You think the table over there is large, I may think it is small. We measure
it and find that it is 0.66 metres square. We now characterise the table in a way that
is less beholden to personal experience.
Science begins when we escape our first-person subjective experience

Thus measurement takes us further from experience and the phenomena of
subjective consciousness to a realm where things are described in abstract but
quantitative terms. To do its work, physical science has to discard "secondary
qualities", such as colour, warmth or cold, taste - in short, the basic contents of
consciousness. For the physicist then, light is not in itself bright or colourful, it is a
mixture of vibrations in an electromagnetic field of different frequencies. The material
world, far from being the noisy, colourful, smelly place we live in, is colourless, silent,
full of odourless molecules, atoms, particles, whose nature and behaviour is best
described mathematically. In short, physical science is about the marginalisation, or
even the disappearance, of phenomenal appearance/qualia, the redness of red wine
or the smell of a smelly dog.

Consciousness, on the other hand, is all about phenomenal appearances/qualia. As
science moves from appearances/qualia and toward quantities that do not
themselves have the kinds of manifestation that make up our experiences, an
account of consciousness in terms of nerve impulses must be a contradiction in
terms. There is nothing in physical science that can explain why a physical object
such as a brain should ascribe appearances/qualia to material objects that do not
intrinsically have them.

Material objects require consciousness in order to "appear". Then their "appearings"
will depend on the viewpoint of the conscious observer. This must not be taken to
imply that there are no constraints on the appearance of objects once they are
objects of consciousness.

Our failure to explain consciousness in terms of neural activity inside the brain inside
the skull is not due to technical limitations which can be overcome. It is due to the
self-contradictory nature of the task, of which the failure to explain "aboutness", the
unity and multiplicity of our awareness, the explicit presence of the past, the initiation
of actions, the construction of self are just symptoms. We cannot explain
"appearings" using an objective approach that has set aside appearings as unreal
and which seeks a reality in mass/energy that neither appears in itself nor has the
means to make other items appear. The brain, seen as a physical object, no more
has a world of things appearing to it than does any other physical object.
Profile

Ray Tallis trained as a doctor, ultimately becoming professor of geriatric medicine at
the University of Manchester, UK, where he oversaw a major neuroscience project.
He is a Fellow of the Academy of Medical Sciences and a writer on areas ranging
from consciousness to medical ethics