Despite our most compelling
intuitions, perhaps the most truly mysterious thing about consciousness is
simply the feeling of mystery we have about it. In this book, Humphreys intends to show us that consciousness is
(merely?) a fully-explainable byproduct of the evolution of organisms with
complex nervous systems. Consciousness
isn’t real magic, but rather a particularly good bit of stage magic,
natural sleight-of-hand so to speak.

In order to explain this
evolutionary conjuring trick, Humphreys distinguishes, at the most basic level,
between sensations and perceptions. Sensations are representations of what is
happening within the organism and produce feelings, while perceptions are
representations of what is happening in the external world and do not
themselves (directly) produce feelings.

Consciousness, according to this
view, is associated with sensations but not perceptions, and further, the
experience of consciousness is simply the expectable result of the evolution of
sensation.

Humphrey’s thesis, as he
recently restated it, may be summarized as follows:

[O]ver evolutionary time, there is a slow but
remarkable change. What happens is that the whole sensory activity gets
“privatised”: the command signals for sensory responses get
short-circuited before they reach the body surface, so that instead of reaching
all the way out to the site of stimulation they now reach only to points closer
and closer in on the incoming sensory nerve, until eventually the whole process
becomes closed off from the outside world in an internal loop within the brain.

Humphreys himself, remarking on A
History of the Mind, noted that in this book he “took a radically new
line about the nature of consciousness, arguing (in contrast to my earlier position)
that consciousness is essentially a matter of having bodily sensations rather
than of having higher level thoughts — and I proposed a theory of how
consciousness as feeling, as distinct from thinking, may have evolved.”

Although such unembarrassed claims
would seem likely, at first blush, to disappoint those who have believed
consciousness to be truly grand, it should come as no significant shock to
readers of Damasio and Dennett, both of whom have also challenged the Cartesian
world view.

The central problem many of us will
have in accepting an epiphenomenal view of consciousness is the feeling
that our consciousness is (almost literally) who we are, and that it
exists independently in the universe, distinct from everything that isn’t
us. Unhappy though it may seem,
Humphreys does a very good job of explaining how consciousness could, after all, evolve naturally in, and extend
naturally from, complex biological systems (and demonstrates that it is not at all
unique to the human species). Consciousness
is not, in this view, what we are, but rather what we are produces
consciousness. This is not intuitively
clear, of course. After all, we are
aware of a conscious self (illusory or not) that appears to be the primary
agent in our lives, and we would not ascribe this type of awareness to other
animals.

Because it broadly straddles the
field with its philosophical stance, Humphrey’s book, published over a decade
ago, still seems quite current. It
presents a progressive, stepwise argument for the evolution of consciousness
from a fundamental sensation-response form to the incredible rich experience
we, as humans, now claim to experience.
And while this book may leave the reader wondering how an amoeba’s consciousness
is then different than our own, the struggle to understand this question can
serve as a guide to sort out the differences between consciousness per se, and
the consciousness we have of being an individual self.

Humphreys clearly ranks among that
exceptional group of scientists who are also philosophers of a literary bent;
Dennett has described
him as “a great romantic scientist, which sounds like a contradiction
in terms, but it isn’t.”

Having produced at least 84 papers
and 9 books, Humphreys is renowned for his literary talent as well, and A
History of the Mind is a striking example of his writing ability. Due to the necessary complexity of the
material, some sections of the book call for careful re-reading before going
forward. And at the end, some readers
might wish that he had put the last chapter first, because in it the author so
directly recaps and reasonably summarizes the entire course of the reader’s
journey through the book. Ultimately,
however, the journey will be found well worth the effort.

© 2003 Keith Harris

Keith
Harris, Ph.D., is a clinical psychologist and supervises the research
section of the Department of Behavioral Health, San Bernardino County,
California. His interests include the empirical basis for psychotherapy
research (and its design), human decision-making processes, and the shaping of
human nature by evolutionary forces.

Categories: Psychology, Philosophical