Passage from Chapter 1,
"What to Do Next"
by William H. Calvin
Science Masters (BasicBooks in the US,
Weidenfeld and Nicolson in the UK)
? 1996 William H. Calvin; Reprinted with permission from Science Masters
(Issue 8 ? posted May 16, 1997; archived May 30, 1997)
Editor's Note: How Brains Think is a marvelously provocative
book that "tries to fathom how our inner life evolves from one second to
the next, as we steer ourselves from one topic to another, as we create and
reject alternatives." Author William Calvin suggests that "the
bootstrapping of new ideas works much like the immune response or the
evolution of a new animal species ? except that the brain can turn the
darwinian crank a lot faster, on the time scale of thought and action."
Drawing on anthropology, evolutionary biology, linguistics, and the
neurosciences,
this book is an expansion of Calvin's article "The Emergence of
Intelligence"
from Scientific American's October 1994 special issue of Life in the
Universe.
Piaget used to say that intelligence is what you use when
you don't know
what to do (an apt description of my present predicament as I attempt to
write about intelligence). If you're good at finding the one right answer to
life's multiple-choice questions, you're smart. But there's more to being
intelligent - a creative aspect, whereby you invent something new "on the
fly." Indeed, various answers occur to your brain, some better than
others.
Every time we contemplate the leftovers in the
refrigerator, trying to
figure out what else needs to be fetched from the grocery store before
fixing dinner, we're exercising an aspect of intelligence not seen in even
the smartest ape. The best chefs surprise us with interesting combinations
of ingredients, things we would ordinarily never think "went together."
Poets are particularly good at arranging words in ways that overwhelm us
with intense meaning. Yet we're all constructing brand-new utterances
hundreds of times every day, recombining words and gestures to get across a
novel message. Whenever you set out to speak a sentence that you've never
spoken before, you have the same creativity problem as the chefs and poets -
furthermore, you do all your trial-and-error inside your brain, in the last
second before speaking aloud.
We've lately made a lot of progress in locating some
aspects of semantics in
the brain. Frequently we find verbs in the frontal lobe. Proper names, for
some reason, seem to prefer the temporal lobe (its front end; color and tool
concepts tend to be found toward the rear of the left temporal lobe). But
intelligence is a process, not a place. It's a way, involving many brain
regions, by which we grope for new meanings, often
"consciously."
The more experienced writers about intelligence, such as
IQ researchers,
steer clear of the C word. Many of my fellow neuroscientists avoid
consciousness as well (some physicists, alas, have been all too happy to
fill the vacuum with beginner's mistakes). Some clinicians unintentionally
trivialize consciousness by redefining it as mere arousability (though to
talk of the brain stem as the seat of consciousness is to thereby confuse
the light switch with the light!). Or we redefine consciousness as mere
awareness, or the "searchlight" of selective attention.
They're all useful lines of inquiry but they leave out
that activism of your
mental life by which you create - and edit and recreate - yourself. Your
intelligent mental life is a fluctuating view of your inner and outer
worlds. It's partly under your control, partly hidden from your
introspection, even capricious (every night, during your four or five
episodes of dreaming sleep, it is almost totally out of control). This book
tries to fathom how this inner life evolves from one second to the next, as
you steer yourself from one topic to another, as you create and reject
alternatives. It draws from studies of intelligence by psychologists, but
even more from ethology, evolutionary biology, linguistics, and the
neurosciences.
There used to be some good reasons for avoiding a
comprehensive discussion
of consciousness and the intellect. A good tactic in science, especially
when mechanistic-level explanations don't help structure your approach to a
fuzzy subject, is to fragment the problem into bite-size pieces - and that
is, in some sense, what's been going on.
A second reason was to avoid trouble by camouflaging the
real issues to all
but insiders (maintaining deniability, in the modern idiom). Whenever I see
words that have everyday meanings but also far more specific connotations
used only by insider groups, I am reminded of code names. Several centuries
ago, an uncamouflaged mechanistic analogy to mind could get you into big
trouble, even in relatively tolerant western Europe. Admittedly, Julien Offroy de la
Mettrie didn't merely say the wrong thing in casual conversation: this
French physician (1709-1751) published a pamphlet in which he wrote of human
motivations as if they were analogous to energy-releasing springs inside
machines.
That was in 1747; the year before, La Mettrie had fled to
Amsterdam from his
native France. He had written a book, it seems, entitled The Natural
History of the Soul. The Paris parliament had disliked it to the point
of ordering all copies burned.
This time, La Mettrie took the precaution of publishing
his pamphlet,
entitled Man a
Machine, anonymously. The Dutch, considered the most tolerant people in
Europe, were scandalized and tried with a vengeance to discover who the
pamphlet's author was. They nearly found out, and so La Mettrie was forced
to flee once more - this time to Berlin, where he died four years later, at
the age of forty-two.
Though he was clearly ahead of his time, La Mettrie didn't
invent the
machine metaphor. That's usually ascribed to Rene
Descartes
(1596-1650), writing a century earlier, in his De Homine. He too
had moved
to Amsterdam from his native France, at about the same time that Galileo was
getting into trouble with the Vatican over the scientific method itself.
Descartes didn't have to flee Holland, as did La Mettrie; he took the
precaution, one might say, of publishing his book a dozen years after he was
safely dead.
Descartes and his followers weren't trying to banish all
talk of spirits;
indeed, one of their characteristic concerns was to identify exactly where
in the brain lay the "seat of the soul." This endeavor was a continuation of
a scholastic tradition which focused on the big reservoirs of cerebrospinal
fluid inside the brain called the ventricles. Religious scholars of 500
years ago thought that the subdivisions of the soul were housed in these
cavities: memory in one; fantasy, common sense and imagination in another;
rational thought and judgment in a third. Like the bottle with the genie
inside, the ventricles were supposedly containers for spirits. Descartes
thought that the pineal gland was a better locale for the seat of
government, on the grounds that it was one of the few brain structures that
didn't come in pairs.
Here at the fin de millennium, though there are theocratic
countries where
using code names would still be a good idea, we are generally more at ease
when it comes to machine metaphors for mind. We can even discuss principled
grounds for disputing any analogy of mind to machine. Minds, the argument
goes, are creative and unpredictable; the machines we know are unimaginative
but reliable - so machines such as digital computers initially seem like an
unreasonable analogy.
Fair enough. But what Descartes established was that it
was useful to talk
of the brain as if it were a machine. You tend to make progress that way,
peeling away the layers of the onion. Even if there is "something else"
hidden beneath the obscuring layers, the scientist tentatively assumes that
there isn't anything fundamentally unknowable, in order to test the
alternative explanations. This scientific tactic -
not to be confused with a scientific conclusion - has produced a revolution
in how we see ourselves.
Mechanistic approaches to mind were, for a long time,
missing an essential
ingredient: a bootstrap mechanism. We're used to the idea that a fancy
artifact such as a watch requires an even fancier watch designer. It's
common sense - just as Aristotle's physics still is (despite being
wrong).
But, ever since Darwin, we've known that fancy things can
also emerge
(indeed, self-organize) from simpler beginnings. Even highly educated
people, as the philosopher Daniel Dennett notes in the preface to Darwin's
Dangerous Idea, can be uncomfortable with such bootstrapping notions
:Darwin's theory of evolution by
natural selection has always fascinated me, but over the years I have found
a surprising variety of thinkers who cannot conceal their discomfort with
his great idea, ranging from nagging skepticism to outright hostility. I
have found not just
lay people and religious thinkers, but secular philosophers, psychologists,
physicists, and even biologists who would prefer, it seems, that Darwin were
wrong.
But not all. Only fifteen years after the 1859 publication of On the Origin
of Species, the psychologist William
James was
writing letters to friends about his notion that thought involved a
Darwinian process in the mind. More than a century later, we are only
beginning to flesh out this idea with appropriate brain mechanisms for
Darwinism. For several decades, we've been talking about selective survival
of overproduced synapses. And that's only the cardboard version of
Darwinism, analogous to carving a pattern into a wood block. Now we're also
seeing brain wiring that could operate the full-fledged Darwinian process,
and probably on the milliseconds-to-minutes time scale of
consciousness.
This shaping-up-the-improbable version of Darwinism
involves generating lots
of copies of certain cerebral firing patterns, letting them vary somewhat,
and then letting variants compete for dominance over a workspace (rather as
those variants called bluegrass and crabgrass compete for my back yard). The
competition is biased by how well those spatio-temporal firing patterns
resonate with the "bumps and ruts
in the road" - the memorized patterns stored in the synaptic strengths. Such
Darwin Machines are a favorite topic of mine, as you'll see.
William Calvin is a theoretical neurophysiologist at the University of
Washington. Besides authoring several books and articles on brains and
human evolution, he produces the webzine Science Surf
and has written two
novels for the Internet -
Synchronized and
Unlisted (read both on the Web to the accompaniment of Bach).
How Brains Think
