Darwin's Dangerous Idea - Evolution and the Meaning of Life

206 BIOLOGY IS ENGINEERING The Computer That Learned to Play Checkers 207
path is the path of Artificial Intelligence, in an organism with genuine intentionality—such
as yourself—there are, right now, many parts, and some of
these parts exhibit a sort of semi-intentionality, or mere as if intention-ality,
or pseudo-intentionality—call it what you like—and your own genuine, fully
fledged intentionality is in fact the product (with no further miracle
ingredients) of the activities of all the semi-minded and mindless bits that
make you up (this is the central thesis defended in Dennett 1987b, 1991a).
That is what a mind is—not a miracle-machine, but a huge, semi-designed,
self-redesigning amalgam of smaller machines, each with its own design
history, each playing its own role in the "economy of the soul." (Plato was
right, as usual, when he saw a deep analogy between a republic and a
person—but of course he had much too simple a vision of what this might
mean.)
There is a deep affinity between the synchronic and diachronic paths to
intentionality. One way of dramatizing it is to parody an ancient anti-
Darwinian sentiment: the monkey's uncle. Would you want your daughter to
marry a robot? Well, if Darwin is right, your great-great-... grandmother was
a robot! A macro, in fact. That is the unavoidable conclusion of the previous
chapters. Not only are you descended from macros; you are composed of
them. Your hemoglobin molecules, your antibodies, your neurons, your
vestibular-ocular reflex machinery—at every level of analysis we find
machinery that dumbly does a wonderful, elegantly designed job. We have
ceased to shudder, perhaps, at the scientific vision of viruses and bacteria
busily and mindlessly executing their subversive projects—horrid little automata
doing their evil deeds. But we should not think that we can take
comfort in the thought that they are alien invaders, so unlike the more
congenial tissues that make up us. We are made of the same sorts of automata
that invade us—no halos of elan vital distinguish your antibodies from the
antigens they combat; they simply belong to the club that is you, so they fight
on your behalf.
Can it be that if you put enough of these dumb homunculi together you
make a real conscious person? The Darwinian says there could be no other
way of making one. Now, it certainly does not follow from the fact that you
are descended from robots that you are a robot. After all, you are also a direct
descendant of some fish, and you are not a fish; you are a direct descendant
of some bacteria, and you are not a bacterium. But unless dualism or vitalism
is true (in which case you have some extra, secret ingredient in you ), you are
made of robots—or what comes to the same thing, a collection of trillions of
macromolecular machines. And all of these are ultimately descended from the
original macros. So something made of robots can exhibit genuine
consciousness, or genuine intentionality, because you do if anything does.
No wonder, then, that there should be so much antagonism to both
Darwinian thinking and Artificial Intelligence. Together they strike a fundamental
blow at the last refuge to which people have retreated in the face of
the Copernican Revolution: the mind as an inner sanctum that science cannot
reach. (See Mazlish 1993) It is a long and winding road from molecules to
minds, with many diverting spectacles along the way—and we will tarry over
the most interesting of these in subsequent chapters—but now is the time to
look more closely than usual at the Darwinian beginnings of Artificial
Intelligence.
5. THE COMPUTER THAT LEARNED TO PLAY CHECKERS
Alan Turing and John von Neumann were two of the greatest scientists of the
century. If anybody could be said to have invented the computer, they did,
and their brainchild has come to be recognized as both a triumph of
engineering and an intellectual vehicle for exploring the most abstract realms
of pure science. Both thinkers were at one and the same time awesome
theorists and deeply practical, epitomizing an intellectual style that has been
playing a growing role in science since the Second World War. In addition to
creating the computer, both Turing and von Neumann made fundamental
contributions to theoretical biology. Von Neumann, as we have already noted,
applied his brilliant mind to the abstract problem of self-replication, and
Turing (1952) did pioneering work on the most basic theoretical problems of
embryology or morphogenesis: how can the complex topology—the shape—
of an organism arise from the simple topology of the single fertilized cell
from which it grows? The process begins, as every high-school student
knows, with an event of quite symmetrical division. (As Francois Jacob has
said, the dream of every cell is to become two cells.) Two cells become four,
and four become eight, and eight become sixteen; how do hearts and livers
and legs and brains get started under such a regime? 12 Turing saw the
continuity between such molecular-level problems and the problem of how a
poet writes a sonnet, and from the earliest days of computers, the ambition of
those who saw what Turing saw has
12. Two highly accessible accounts of Turing's work on morphogenesis are Hodges (
1983, ch. 7), and Stewart and Golubitsky ( 1992), which also discusses their relation to
more recent theoretical explorations in the field. Beautiful as Turing's ideas are, they
probably have at best a very attenuated application to real biological systems. John
Maynard Smith (personal communication) recalls being entranced by Turing's 1952
paper (which his supervisor, J. B. S. Haldane, had shown him), and for years he was
convinced that "my fingers must be Turing waves; my vertebrae must be Turing waves"—
but he eventually came to realize, reluctantly, that it could not be that simple and
beautiful.