Darwin's Dangerous Idea (15 page)

term of abuse, is "reductionism." Those who yearn for skyhooks call those who eagerly settle for cranes "reductionists," and they can often make reductionism seem philistine and heartless, if not downright evil. But like

• See also his discussion of Lewontin, Rose, and Kamin's (1984 ) idiosyncratic version of most terms of abuse, "reductionism" has no fixed meaning. The central reductionism—Dawkins aptly calls it their "private bogey"—in the second edition of
The
image is of somebody claiming that one science "reduces" to another: that
Se!ftsh Gene (I989z\
p. 331.

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Who's Afraid of Reductionism?
83

thing, from
greedy reductionism,
which is not. The difference, in the context A more reasonable and realistic fear is that the greedy abuse of Darwinian of Darwin's theory, is simple: greedy reductionists think that everything can reasoning might lead us to deny the existence of real levels, real complex-be explained without cranes; good reductionists think that everything can be ities, real phenomena. By our own misguided efforts, we might indeed come explained without skyhooks.

to discard or destroy something valuable. We must work hard to keep these There is no reason to be compromising about what I call good reduc-two fears separate, and we can begin by acknowledging the pressures that tionism. It is simply the commitment to non-question-begging science with-tend to distort the very description of the issues. For instance, there is a out any cheating by embracing mysteries or miracles at the outset. (For strong tendency among many who are uncomfortable with evolutionary another perspective on this, see Dennett 1991a, pp. 33-39.)
Three
cheers for theory to exaggerate the amount of disagreement among scientists ("It's just a that brand of reductionism—and I'm sure Weinberg would agree. But in their theory, and there are many reputable scientists who don't accept this"), and I eagerness for a bargain, in their zeal to explain too much too fast, scientists must try hard not to overstate the compensating case for what "science has and philosophers often underestimate the complexities, trying to skip whole shown." Along the way, we will encounter plenty of examples of genuine layers or levels of theory in their rush to fasten everything securely and ongoing scientific disagreement, and unsettled questions of fact. There is no neatly to the foundation. That is the sin of greedy reductionism, but notice reason for me to conceal or downplay these quandaries, for no matter how that it is only when overzealousness leads to falsification of the phenomena they come out, a certain amount of corrosive work has already been done by that we should condemn it. In itself, the desire to reduce, to unite, to explain Darwin's dangerous idea, and can never be undone.

it all in one big overarching theory, is no more to be condemned as immoral We should be able to agree about one result already. Even if Darwin's than the contrary urge that drove Baldwin to his discovery. It is not wrong to relatively modest idea about the origin of species came to be
rejected
by yearn for simple theories, or to yearn for phenomena that no simple (or science—yes, utterly discredited and replaced by some vastly more powerful complex!) theory could ever explain; what is wrong is zealous (and currently unimaginable) vision—it would still have irremediably sapped misrepresentation, in either direction.

conviction in any reflective defender of the tradition expressed by Locke. It Darwin's dangerous idea is reductionism incarnate,9 promising to unite and has done this by opening up new possibilities of imagination, and thus utterly explain just about everything in one magnificent vision. Its being the idea of destroying any illusions anyone might have had about the soundness of an an
algorithmic
process makes it all the more powerful, since the substrate argument such as Locke's
a priori
proof of the
inconceivability
of Design neutrality it thereby possesses permits us to consider its application to just without Mind. Before Darwin, this was inconceivable in the pejorative sense about anything. It is no respecter of material boundaries. It applies, as we that no one knew how to take the hypothesis seriously. Proving it is another have already begun to see, even to itself. The most common fear about matter, but the evidence does in fact mount, and we certainly can and must Darwin's idea is that it will not just explain but
explain away
the Minds and take it seriously. So whatever else you may think of Locke's argument, it is Purposes and Meanings that we all hold dear. People fear that once this now as obsolete as the quill pen with which it was written, a fascinating universal acid has passed through the monuments we cherish, they will cease museum piece, a curiosity that can do no real work in the intellectual world to exist, dissolved in an unrecognizable and unlovable puddle of scientistic today.

destruction. This cannot be a sound fear; a
proper
reductionists explanation of these phenomena would leave them still standing but just demystified, unified, placed on more secure foundations. We might learn some surprising CHAPTER 3:
Darwin's dangerous idea is that Design can emerge from mere
or even shocking things about these treasures, but unless our valuing these
Order via an algorithmic process that makes no use of pre-existing Mind.

things was based all along on confusion or mistaken identity, how could
Skeptics have hoped to show that at least somewhere in this process, a
increased understanding of them diminish their value in
helping hand (more accurately, a helping Mind) must have been provided
—
a

-.10

skyhook to do some of the lifting. In their attempts to prove a role for
our eyes?

skyhooks, they have often discovered cranes: products of earlier algorithmic
processes that can amplify the power of the basic Darwinian algorithm,
making the process locally swifter and more efficient in a nonmiraculous
way. Good reductionists suppose that all Design can be explained without
9. Yes, incarnate. Think about it: would we want to say it was reductionism
in spirit?

skyhooks; greedy reductionists suppose it can all be explained without
10. Everybody knows how to answer this rhetorical question with another: "Are you so
cranes.

in love with Truth at all costs that you would want to know if your lover were unfaithful to you?" We are back where we started. I for one answer that I love the world so much that I
am sure I want to know the truth about it.

84 UNIVERSAL ACID

CHAPTER 4:
How did die historical process of evolution actually make the
Tree of Life? In order to understand the controversies about the power of
natural selection to explain the origins of all the Design, we must hrst learn
CHAPTER FOUR

how to visualize the Tree of Life, getting clear about some easily misunderstood features of its shape, and a few of the key moments in its history.

The Tree of Life

1. How SHOULD WE VISUALIZE THE TREE OF LIFE?

Extinction has only separated groups: it has by no means made them;
for if every form which has ever lived on this earth were suddenly to
reappear, though it would be quite impossible to give definitions by
which each group could be distinguished from other groups, as all
would blend together by steps as fine as those between the finest
existing varieties, nevertheless a natural classification, or at least a
natural arrangement, would be possible.

—CHARLES DARWIN,
Origin,
p. 432

In the previous chapter, the idea of R-and-D work as analogous to moving around in something I called Design Space was introduced on the fly, without proper attention to detail or a definition of terms. In order to sketch the big picture, I helped myself to several controversial claims, promising to defend them later. Since the idea of Design Space is going to be put to heavy use, I must now secure it, and, following Darwin's lead, I will once more begin in the middle, by looking first at some
actual
patterns in some relatively well-explored spaces. These will serve as guides, in the next chapter, to a more general perspective on
possible
patterns, and the way in which certain sorts of processes bring possibilities into reality.

Consider the Tree of Life, the graph that plots the time-line trajectories of all the things that have ever lived on this planet—or, in other words, the total fan-out of
offspring.
The rules for drawing the graph are simple. An organism's time line begins when it is born and stops when it dies, and either there are offspring lines emanating from it or there aren't. The close-up view of an organism's offspring lines—if there are any—would vary in
appearance depending on several facts: whether the organism reproduces by fission or budding, or giving birth to eggs or live young, and whether the

86 THE TREE OF LIFE

How Should We Visualize the Tree of Life?
87

parent organism survives to coexist for a while with its offspring. But such
lier
on top and
later
on the bottom, in which case our diagram shows microdetails of the fan-out will not in general concern us at this time. There ancestors and their
descendants.
Darwin used this convention when he spoke is no serious controversy about the fact that all the diversity of life that has of speciation as modification with
descent,
and of course in the title of his ever existed on this planet is derived from this single fan-out; the contro-work on human evolution,
The Descent of Man, and Selection in Relation to
versies arise about how to discover and describe
in general terms
the various
Sex
(1871). Alternatively, we can draw a tree in normal orientation, so it forces, principles, constraints, etc., that permit us to give a scientific looks like a tree, on which the later "descendants" compose die limbs and explanation of the patterns in all this diversity.

branches that
rise,
over time, from the trunk and the initial roots. Darwin also The Earth is about 4.5 billion years old, and the first life forms appeared exploited this convention—for instance, in the only diagram in
Origin
—but quite "soon"; the simplest single-celled organisms—the
prokaryotes
—ap-also, along with everyone else, in uses of expressions that align
higher
with peared at least 35 billion years ago, and for probably another 2 billion years,
later.
Both metaphor groups coexist with little turbulence in the language that was all the life there was. bacteria, blue-green algae, and their equally and diagrams of biology today. (This tolerance for topsy-turvy imagery is not simple kin. Then, about 1.4 billion years ago, a major revolution happened: restricted to biology. "Family trees" are more often than not drawn with the some of these simplest life forms literally joined forces, when some bacteria-ancestors at the top, and generative linguists, among others, draw their like prokaryotes invaded the membranes of other prokaryotes, creating the derivational trees upside down, with the "root" at the top of the page.) Since I have already proposed labeling the vertical dimension in Design
eukaryotes
—cells with nuclei and other specialized internal bodies (Mar-Space as a measure of amount of Design, so that
higher
=
more designed,
we gulis 1981). These internal bodies, called
organelles
or
plastids,
are the key must be careful to note that in the Tree of Life (drawn right-side-up, as I design innovation opening up the regions of Design Space inhabited today.

propose to do )
higher = later
(and nothing else ). It does not
necessarily
The
chloroplasts
in plants are responsible for photosynthesis, and
mito-mean more designed. What is the relation between time and Design, or what
chondria,
which are to be found in every cell of every plant, animal, could it be? Could things that are more designed come first and fungus—every organism with nucleated cells—are the fundamental oxygen-processing energy-factories that permit us all to fend off the Second Law of Thermodynamics by exploiting the materials and energy around us. The prefix "eu" in Greek means "good," and from our point of view the eukaryotes were certainly an improvement, since, thanks to their internal complexity, they could specialize, and this eventually made possible the creation of multicelled organisms, such as ourselves.

That
second
revolution—the emergence of the first multicelled organisms—had to wait 700 million years or so. Once multicelled organisms were on the scene, the pace picked up. The subsequent fan-out of plants and animals—from ferns and flowers to insects, reptiles, birds, and mammals—

has populated the world today with millions of different species. In the process, millions of other species have come and gone. Surely many more species have gone extinct than now exist—perhaps a hundred extinct spe-cies for every existent species.