28 | New Scientist | 2 November 2019
Book
The Feeling of Life Itself:
Why consciousness
is widespread but
can’t be computed
Christof Koch
MIT PressTHE nature of consciousness is
notoriously hard to crack and
there are so many speculative
ideas about it that it is hard to keep
track of them. Another book on
the subject may seem one too
many, but Christof Koch’s deep
synthesis of a profound theory
of consciousness and the latest
neuroscience is an exception.
At last, we have a theory of
consciousness that makes clear
and testable predictions, many
wholly unexpected. It says even
the cleverest computers can never
be conscious, while many more
species of animal than we thought
have sparks of consciousness.
More exotically, it implies that it
may be possible to experience the
great void – the deep meditative
state that mystics seek – and for
lovers to meld minds. But perhaps
most important of all, the theory
suggests that consciousness has a
function and thus why it evolved.
Koch, who runs the Allen
Institute for Brain Science in
Seattle, spent decades working
with the late Nobel laureate
Francis Crick searching for the
parts of the brain closely involved
in generating consciousness.
Koch’s knowledge of neuroscience
complements the idea at the heart
of The Feeling of Life Itself.
That idea, writes Koch, “is the
singular intellectual creation
of Giulio Tononi, a brilliant,
sometimes cryptic, polyglot and
polymath renaissance scholar”.
Tononi is a professor at
the University of WisconsinWhat is it like to be conscious?
Can a radical theory finally explain why consciousness evolved, how it works
and predict where we will find it? Alun Anderson tries a mind-stretching readwith whom Koch now
works closely. He devised the
integrated information theory of
consciousness, which drew public
attention for its “consciousness
meter”, a method of searching for
awareness in people thought to be
in vegetative states. But this is the
first book to try to explain the
theory to a general audience.
Tononi’s approach doesn’t start
in the brain or in philosophy, as
you might expect, but by asking
a simple question: what is
conscious experience like?
Its essence can be captured in
five properties, Koch believes. First
and foremost, consciousness is
“intrinsic”, a private experience.
I know that I am conscious and
have experiences but can’t
observe your consciousness or
be certain that you feel anything.
Consciousness exists for itself.
Experience is also “structured”,
containing many different things.
For example, someone sits in front
of you on the bus, traffic passes by,
your neighbour’s headphones leak
bass and so on.
And each conscious experience
is “informative”, it differs from
every other one. It is “integrated”
into one whole picture, and it is
“definite” in that you only have
one conscious experience at a
time, which can’t be reduced into
parts without losing something.
The five properties need some
thought but Koch explains them
well and lets you attempt to negate
them to prove that they “cannot
be doubted”. Let’s agree and follow
Koch with a leap from these five
properties of experience to five
matching principles that must be
obeyed for a physical system
to generate consciousness.
This is Tononi’s great
achievement. He proposes five
principles (intrinsic existence,Views Culture
MARCUS ROSE/PANOScomposition, information,
integration and exclusion) that
make it possible to see whether
any set of mechanisms, be they
neurons or electronic networks,
can generate experience. If a
system doesn’t produce intrinsic
experience, it isn’t conscious, if
the whole can be reduced to parts,
it isn’t conscious, and so on.
Tononi’s big leap is to go from
experience to a defining physical
theory of consciousness, without
dabbling with the brain. That is
truly radical.
Koch provides a metaphor to
help show how the theory deals
with “intrinsic existence”, the
private nature of consciousness.
He goes back 2400 years to Plato’s
dialogue with the “stranger
from Elea”, who argues that for
something to be said to exist, it
must affect something else, or be“ At last we have a theory
of consciousness that
makes clear, testable
predictions, many
wholly unexpected”