http://www.nytimes.com/2007/11/18/magazine/18wwln-lede-t.html?_r=1&ref=magaz
ine&oref=slogin
November 18, 2007
The Way We Live Now
Mind of a Rock
By JIM HOLT
Most of us have no doubt that our fellow humans are conscious. We are also
pretty sure that many animals have consciousness. Some, like the great ape
species, even seem to possess self-consciousness, like us. Others, like
dogs and cats and pigs, may lack a sense of self, but they certainly
appear to experience inner states of pain and pleasure. About smaller
creatures, like mosquitoes, we are not so sure; certainly we have few
compunctions about killing them. As for plants, they obviously do not have
minds, except in fairy tales. Nor do nonliving things like tables and
rocks.
All that is common sense. But common sense has not always proved to be
such a good guide in understanding the world. And the part of our world
that is most recalcitrant to our understanding at the moment is
consciousness itself. How could the electrochemical processes in the lump
of gray matter that is our brain give rise to
or, even more mysteriously, be
the dazzling technicolor play of consciousness, with its transports of
joy, its stabs of anguish and its stretches of mild contentment
alternating with boredom? This has been called
the most important problem in the biological sciences
and even
the last frontier of science.
It engrosses the intellectual energies of a worldwide community of brain
scientists, psychologists, philosophers, physicists, computer scientists
and even, from time to time, the Dalai Lama.
So vexing has the problem of consciousness proved that some of these
thinkers have been driven to a hypothesis that sounds desperate, if not
downright crazy. Perhaps, they say, mind is not limited to the brains of
some animals. Perhaps it is ubiquitous, present in every bit of matter,
all the way up to galaxies, all the way down to electrons and neutrinos,
not excluding medium-size things like a glass of water or a potted plant.
Moreover, it did not suddenly arise when some physical particles on a
certain planet chanced to come into the right configuration; rather, there
has been consciousness in the cosmos from the very beginning of time.
The doctrine that the stuff of the world is fundamentally mind-stuff goes
by the name of panpsychism. A few decades ago, the American philosopher
Thomas Nagel showed that it is an inescapable consequence of some quite
reasonable premises. First, our brains consist of material particles.
Second, these particles, in certain arrangements, produce subjective
thoughts and feelings. Third, physical properties alone cannot account for
subjectivity. (How could the ineffable experience of tasting a strawberry
ever arise from the equations of physics?) Now, Nagel reasoned, the
properties of a complex system like the brain don
t just pop into existence from nowhere; they must derive from the
properties of that system
s ultimate constituents. Those ultimate constituents must therefore have
subjective features themselves
features that, in the right combinations, add up to our inner thoughts
and feelings. But the electrons, protons and neutrons making up our brains
are no different from those making up the rest of the world. So the entire
universe must consist of little bits of consciousness.
Nagel himself stopped short of embracing panpsychism, but today it is
enjoying something of a vogue. The Australian philosopher David Chalmers
and the Oxford physicist Roger Penrose have spoken on its behalf. In the
recent book
Consciousness and Its Place in Nature,
the British philosopher Galen Strawson defends panpsychism against
numerous critics. How, the skeptics wonder, could bits of mind-dust, with
their presumably simple mental states, combine to form the kinds of
complicated experiences we humans have? After all, when you put a bunch of
people in the same room, their individual minds do not form a single
collective mind. (Or do they?) Then there is the inconvenient fact that
you can
t scientifically test the claim that, say, the moon is having mental
experiences. (But the same applies to people
how could you prove that your fellow office workers aren
t unconscious robots, like Commander Data on
Star Trek
?) Finally, there is the sheer loopiness of the idea that something like a
photon could have proto-emotions, proto-beliefs and proto-desires. What
could the content of a photon
s desire possibly be?
Perhaps it wishes it were a quark,
one anti-panpsychist cracked.
Panpsychism may be easier to parody than to refute. But even if it proves
a cul-de-sac in the quest to understand consciousness, it might still help
rouse us from a certain parochiality in our cosmic outlook. We are
biological beings. We exist because of self-replicating chemicals. We
detect and act on information from our environment so that the
self-replication will continue. As a byproduct, we have developed brains
that, we fondly believe, are the most intricate things in the universe. We
look down our noses at brute matter.
Take that rock over there. It doesn
t seem to be doing much of anything, at least to our gross perception. But
at the microlevel it consists of an unimaginable number of atoms connected
by springy chemical bonds, all jiggling around at a rate that even our
fastest supercomputer might envy. And they are not jiggling at random. The
rock
s innards
see
the entire universe by means of the gravitational and electromagnetic
signals it is continuously receiving. Such a system can be viewed as an
all-purpose information processor, one whose inner dynamics mirror any
sequence of mental states that our brains might run through. And where
there is information, says panpsychism, there is consciousness. In David
Chalmers
s slogan,
Experience is information from the inside; physics is information from the
outside.
But the rock doesn
t exert itself as a result of all this
thinking.
Why should it? Its existence, unlike ours, doesn
t depend on the struggle to survive and self-replicate. It is indifferent
to the prospect of being pulverized. If you are poetically inclined, you
might think of the rock as a purely contemplative being. And you might
draw the moral that the universe is, and always has been, saturated with
mind, even though we snobbish Darwinian-replicating latecomers are too
blinkered to notice.
Jim Holt, a contributing writer, is working on a book about the puzzle of
existence.