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

444 THE EMPEROR'S NEW MIND, AND OTHER FABLES
3. THE PHANTOM QUANTUM-GRAVITY COMPUTER:
LESSONS FROM LAPLAND
I am a strong believer in the power of natural selection. But I do not see
how natural selection, in itself, can evolve algorithms which could have
the kind of conscious judgements of the validity of other algorithms that
we seem to have.
—ROGER PENROSE 1989, p. 414
/ don't think the brain came in the Darwinian manner. In fact, it is
disprovable. Simple mechanisms can't yield the brain. I think the basic
elements of the universe are simple. Life force is a primitive element of
the universe and it obeys certain laws of action. These laws are not
simple and not mechanical
—KURT GODEL 2
When Penrose insists that the brain is no Turing machine, it is important to
understand what he is not saying. He is not making the obvious (and
obviously irrelevant) claim that the brain is not well modeled by Turing's
original thought-device: a smallish gadget sitting astride a paper tape, examining
one square of the tape at a time. Nobody ever thought otherwise. He
is also not merely saying that the brain is not a serial computer, a "von
Neumann machine,'' but, rather, a massively parallel computer. And he is not
just saying that the brain makes use of randomness or pseudo-randomness in
running its algorithms. He sees—though some others have not—that
algorithms availing themselves of large doses of randomness are still
algorithms within the purview of Artificial Intelligence, and still fall under
the limitations Godel's Theorem places on all Turing machines, of whatever
size and shape. 3
2. A remark made in 1971, quoted in Wang 1993, p. 133. See also Wang 1974, p. 326:
"Godel believes that mechanism in biology is a prejudice of our time which will be
disproved. In this case, one disproval, in Godel's opinion, will consist in a mathematical
theorem to the effect that the formation within geological times of a human body by the
laws of physics ( or any other laws of a similar nature ), starting from a random distribution
of the elementary particles and the field, is as unlikely as the separation by chance
of the atmosphere into its components."
3. Someone who doesn't realize this is Gerald Edelman, whose "neural Darwinism"
simulations are both parallel and heavily stochastic (involving randomness), a fact he
often cites, mistakenly, as evidence that his models are not algorithms, and that he himself
is not engaged in "strong AI" ( e.g., Edelman 1992 ). He is; his protestations to the contrary
betray an elementary misunderstanding of computers, but that just goes to show, as
The Phantom Quantum-Gravity Computer 445
Moreover, in the wake of the commentary his book provoked, Penrose
now grants that heuristic programs are algorithms as well, and acknowledges
that, if he is to find an argument against AI, he has to concede their
tremendous power to track the truths of arithmetic and everything else, if not
perfectly, then at least impressively. He offers a further point of clarification:
any computer that operates by indulging in interactions with an external
environment is an algorithmic computer provided the external environment is
itself entirely algorithmic. (If skyhooks grew like toadstools—or, more to the
point, like oracles perched on toadstools—and a computer was helped along
by its occasional communication with these skyhooks, then what it did would
be no algorithm.)
Now, with all this useful clarification in place, what does Penrose maintain?
In May 1993, I spent a week with Penrose and some Swedish physicists
and other scientists discussing our different views about these matters, at a
workshop in Abisko, a tundra-research station well north of the Arctic Circle
in Sweden. Perhaps the midnight sun helped as much as our Swedish hosts to
illuminate the path, but, in any event, I think we both came away
enlightened. Penrose proposes a revolution in physics, centered on a new—
and still unformulated—theory of "quantum gravity," which he hopes will
explain how the human brain transcends the limitations of algorithms. Does
Penrose envisage the human brain, with its special quantum-physics powers,
to be a skyhook or a crane? That was the question I went to Sweden to
answer, and the answer I came back with is this: He has definitely been
looking for a skyhook. I think he'd settle for a new crane—but I doubt that
he's found one.
Descartes and Locke, and more recently Edgar Allan Poe, Kurt Godel, and
J. R. Lucas, thought that the alternative to a "mechanical" mind would be an
immaterial mind, or a soul, to speak with tradition. Hubert Dreyfus and John
Searle, more recent skeptics about AI, have shunned such dualism and opined
that the mind is indeed just the brain, but the brain is not any ordinary
computer; it has "causal powers" (Searle 1985) that go beyond the running of
any algorithms. Neither Dreyfus nor Searle has been very forthcoming about
what special powers these might be, or which of the physical sciences might
be the right one to give an account of them, but others have wondered
whether physics might hold the key. To many of them, Penrose appears to be
a knight in shining armor.
Quantum physics to the rescue! Several different proposals have been
advanced over the years about how quantum effects might be harnessed to
give the brain special powers beyond those of any ordinary computer. J. R.
everybody in AI knows, that although you may not have "Absolute Ignorance" (as Mac-
Kenzie anonymously put it, back in chapter 3, p 65), you still don't have to understand
what you are making in order to make it.