 |
|
The knot in
the brain
A.C.
Grayling, reader in Philosophy, Birkbeck College, University of London |
Science is piercing the mystery of the brain, but consciousness remains an enigma. |
Philosophers
since Descartes have striven to understand the connections between the material world,
the body and the mind. Have brain scans brought us to the verge of an answer?
Among the most important
questions still facing human enquiry are those about the mind and its place in nature.
What is mind, and what is it relation to body? How should we best understand our
common sense concepts of such mental phenomena as belief, desire, intention, emotion,
reason and memory? How does the grey matter of the brain give rise to our rich and
vivid experiences of colour, sound, texture, taste and smell?
Discussion of the mind-body problem was given an especially sharp form by Descartes.
He argued that everything that exists falls under the heading either of material
substance or mental substance, where “substance” is a technical term denoting the
most basic kind of existing stuff. He defined the essence of matter as occupancy
of space, and the essence of mind as thought. But by thus making matter and mind
so different, he raised the seemingly insuperable problem of how they interact. How
does a bodily event like pricking oneself result in the mental event of feeling pain?
How does the mental event of thinking “it’s time to get up” cause the bodily event
of rising from bed?
Descartes himself did not have an answer, and his successors had to resort to heroic
solutions to the problem his theory had bequeathed. Their strategy was to accept
dualism but to argue that mind and matter do not in fact interact, their appearance
of doing so being the result of the hidden action of God. Thus for Leibniz, God acted
like a clockmaker, setting the mental and material realms going in exact unison at
the universe’s beginning so that they thereafter act in parallel.
A much more plausible alternative, however, is monism: namely, the view that there
is only one substance. Three possibilities rise to the fore. One is that there is
only matter. The second is that there is only mind. The third is that there is a
neutral substance which gives rise to mind and matter. Each of the three has had
proponents but it is the first option–the reduction or annexation of all mental phenomena
to matter–which has been most influential.
One materialist approach is the “identity theory,” which asserts that mental states
are literally identical with states or processes in the brain. In its earliest form,
it asserted that types of mental phenomena are nothing other than types of brain
occurrences, but this was quickly seen to be too sweeping, for a particular mental
event (e.g. a mental image of the Eiffel tower) might in my brain activate one set
of cells, while in yours another.
A
football match between sociologists and physicists
On the basis of this theory, a number of philosophers currently maintain that as
neuroscience advances, we will be able to eliminate the old-fashioned and imprecise
mental vocabulary we standardly use. Research in neurology and cognitive science
have built an overwhelming case for accepting a very intimate relation between mental
and neurological phenomena. Neuroscientists now have highly detailed empirical knowledge
of brain function and its relation to mental activity, and are able to locate the
seat of many conscious processes in precisely defined brain structures.
But these advances only serve to correlate brain activity with mental occurences;
they do not explain how the former actually produces the latter. Given the persistent
difficulties in identifying that relation precisely, various strategies are proposed.
One is to accept that our ways of talking about mental and physical phenomena are
irreducibly different, even though they are about the same thing. Imagine, for example,
how sociologists and physicists would respectively describe a football match, each
focusing upon features which his particular science can address to describe the same
thing.
The
film inside the mind
Consciousness,
on the other hand, can appear much easier to understand than the relation between
mind and body: anyone capable of thinking is after all intimately conscious of being
conscious. But consciousness is by far the most perplexing mystery facing philosophy
and the neurological sciences. Some philosophers, in the tradition of Descartes,
think that it is too hard for human intelligence to understand. Others even claim
that there is no such thing as consciousness; we are actually zombies, just very
complicated ones. In defiance of these views, enquirers have profited from powerful
new investigative tools, especially brain scanning devices, to watch brains at work.
One result is a great increase in knowledge of brain function and a refined understanding
of the correlation between specific brain areas and specific mental capacities.
The central problem remains, however, of how coloured pictures, evocative smells
and sounds arise in the head as if it were an inner cinema-show. One recent theory
offered by neurophysiologist Antonio Damasio is that consciousness begins as self-reflexive
awareness constituting a primitive level of selfhood, a powerful but vague awareness
of being “I.” Emotional relations to an evolving self and external objects then construct
a model of the world, a feeling of knowing, giving each of us the sense that we are
the owner and viewer of a movie-within-the-brain.
Consciousness has arisen amongst higher mammals, according to these theories, because
of its survival advantage–an organism’s appropriate use of energy and protection
from harm are much enhanced when it is able to place itself in a map of the environment
and make plans about the best courses of action in it. Creatures which are merely
biological automata, even if highly sensitive to their surroundings, would not be
as adaptive as creatures that are genuinely conscious
Debate about the mind has certainly resulted in a widespread consensus that mind
is part of nature and amenable to investigation by scientific means, but there are
still fundamental mysteries about what it is and how it relates to the rest of nature.
The next great leap in understanding the mind will doubtless involve a conceptual
and scientific revolution of such magnitude that we cannot at present envisage it. |
|
|
