Consciousness Is Not In The Brain
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
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
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
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
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
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.
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.
January 7, 2010