Darwin's Dangerous Idea (5 page)

Or perhaps isn't the world really more like a vegetable than an animal?

Have we not the same reason to trace that ideal world into another ideal world, or new intelligent principle? But if we stop, and go no farther; In like manner as a tree sheds its seed into the neighboring fields, and why go so far? Why not stop at the material world? How can we satisfy produces other trees; so the great vegetable, the world, or this planetary ourselves without going on
in infinitum?
And after all, what satisfaction system, produces within itself certain seeds, which, being scattered into is there in that infinite progression? [Pt. IV.)

the surrounding chaos, vegetate into new worlds. A comet, for instance, is the seed of a world.... [Pt. VII.]

Cleanthes has no satisfactory responses to these rhetorical questions, and there is worse to come. Cleanthes insists that God's mind is
like the human
—

One more wild possibility for good measure:

and agrees when Philo adds "the liker the better." But, then, Philo presses on, is God's mind perfect, "free from every error, mistake, or incoherence in his undertakings" (Pt. V)? There is a rival hypothesis to rule out: The Brahmins assert, that the world arose from an infinite spider, who spun this whole complicated mass from his bowels, and annihilates afterwards the whole or any part of it, by absorbing it again, and And what surprise must we entertain, when we find him a stupid resolving it into his own essence. Here is a species of cosmogony, mechanic, who imitated others, and copied an art, which, through a long which appears to us ridiculous; because a spider is a little contemptible succession of ages, after multiplied trials, mistakes, corrections, animal, whose operation we are never likely to take for a model of the deliberations, and controversies, had been gradually improving? Many whole universe. But still here is

worlds might have

32 TELL ME WHY

Hume's Close Encounter
33

a new species of analogy, even in our globe. And were there a planet serve a constancy in the forms, its situation must, of necessity, have all the wholly inhabited by spiders (which is very possible), this inference would same appearance of art and contrivance which we observe at present __

there appear as natural and irrefragable as that which in our planet ascribes A defect in any of these particulars destroys the form; and the matter, of the origin of all things to design and intelligence, as explained by Clean-which it is composed, is again set loose, and is thrown into irregular thes. Why an orderly system may not be spun from the belly as well as from motions and fermentations, till it unite itself to some other regular form __

the brain, it will be difficult for him to give a satisfactory reason. [Pt. VII.]

Suppose ... that matter were thrown into any position, by a blind, unguided force; it is evident that this first position must in all probability be the most confused and most disorderly imaginable, without any resem-Cleanthes resists these onslaughts gamely, but Philo shows fatal flaws in blance to those works of human contrivance, which, along with a symme-every version of the argument that Cleanthes can devise. At the very end of try of parts, discover an adjustment of means to ends and a tendency to the
Dialogues,
however, Philo surprises us by agreeing with Cleanthes: self-preservation __ Suppose, that the actuating force, whatever it be, still continues in matter __ Thus the universe goes on for many ages in a

... die legitimate conclusion is that... if we are not contented with calling continued succession of chaos and disorder. But is it not possible that it the first and supreme cause a
God
or
Deity,
but desire to vary the expres-may settle at last... ? May we not hope for such a position, or rather be sion, what can we call him but
Mind
or
Thought
to which he is jusly assured of it, from the eternal revolutions of unguided matter, and may not supposed to bear a considerable resemblance? [Pt. XII.]

this account for all the appearing wisdom and contrivance which is in the universe?

Philo is surely Hume's mouthpiece in the
Dialogues.
Why did Hume cave Hmm, it seems that something like this might work... but Hume couldn't in? Out of fear of reprisal from the establishment? No. Hume knew he had quite take Philo's daring foray seriously. His final verdict: "A total suspense shown that the Argument from Design was an irreparably flawed bridge be-of judgment is here our only reasonable resource" (Pt. VIII). A few years tween science and religion, and he arranged to have
his Dialogues
published before him, Denis Diderot had also written some speculations that tantaliz-after his death in 1776 precisely in order to save himself from persecution.

ingly foreshadowed Darwin: "I can maintain to you ... that monsters anni-He caved in because
he just couldn't imagine
any other explanation of the hilated one another in succession; that all the defective combinations of origin of the manifest design in nature. Hume could not see how the "curious matter have disappeared, and that there have only survived those in which the adapting of means to ends, throughout all nature" could be due to chance—

organization did not involve any important contradiction, and which could and if not chance, what?

subsist by themselves and perpetuate themselves" (Diderot 1749). Cute ideas What could possibly account for this high-quality design if not an intel-about evolution had been floating around for millennia, but, like most ligent God? Philo is one of the most ingenious and resourceful competitors in philosophical ideas, although they did seem to offer a solution of sorts to the any philosophical debate, real or imaginary, and he makes some wonderful problem at hand, they didn't promise to go any farther, to open up new stabs in the dark, hunting for an alternative. In Part VIII, he dreams up some investigations or generate surprising predictions that could be tested, or speculations that come tantalizingly close to scooping Darwin (and some explain any facts they weren't expressly designed to explain. The evolution more recent Darwinian elaborations) by nearly a century.

revolution had to wait until Charles Darwin saw how to weave an evolutionary hypothesis into an explanatory fabric composed of literally Instead of supposing matter infinite, as Epicurus did, let us suppose it finite.

thousands of hard-won and often surprising facts about nature. Darwin nei-A finite number of particles is only susceptible of finite transpositions: And ther invented the wonderful idea out of whole cloth all by himself, nor it must happen, in an eternal duration, that every possible order or position understood it in its entirety even when he had formulated it. But he did such must be tried an infinite number of times __ Is there a system, an order, an a monumental job of clarifying the idea, and tying it down so it would never economy of things, by which matter can preserve that perpetual agitation, again float away, that he deserves the credit if anyone does. The next chapter which seems essential to it, and yet maintain a constancy in the forms, reviews his basic accomplishment.

which it produces? There certainly is such an economy: For this is actually the case with the present world. The continual motion of matter, therefore, in less than infinite transpositions, must produce this economy or order; and by its very nature, that order, when once established, supports CHAPTER 1:
Before Darwin,
a
"Mind-first" view of the universe reigned
itself, for many ages, if not to eternity. But wherever matter is so poised,
unchallenged; an intelligent God was seen as the ultimate source of all
arranged, and adjusted as to continue in perpetual motion, and yet pre-Design, the ultimate answer to any chain of "Why?" questions. Even David 34 TELL ME WHY

Hume, who deftly exposed the insoluble problems with this vision, and had
glimpses of the Darwinian alternative, could not see how to take it seriously.

CHAPTER 2:
Darwin, setting out to answer a relatively modest question about
CHAPTER TWO

die origin of species, described a process he called natural selection, a
mindless, purposeless, mechanical process. This turns out to be the seed of
an answer to a much grander question: how does Design come into
An Idea Is Born

existence?

1. WHAT IS SO SPECIAL ABOUT SPECIES?

Charles Darwin did not set out to concoct an antidote to John Locke's conceptual paralysis, or to pin down the grand cosmological alternative that had barely eluded Hume. Once his great idea occurred to him, he saw that it would indeed have these truly revolutionary consequences, but at the outset he was not trying to explain the meaning of life, or even its origin. His aim was slightly more modest: he wanted to explain the origin of
species.

In his day, naturalists had amassed mountains of tantalizing facts about living things and had succeeded in systematizing these facts along several dimensions. Two great sources of wonder emerged from this work (Mayr 1982). First, there were all the discoveries about the
adaptations
of organisms that had enthralled Hume's Cleanthes: "All these various machines, and even their most minute parts, are adjusted to each other with an accuracy which ravishes into admiration all men who have ever contemplated them"

(Pt. II). Second, there was the prolific
diversity
of living things—literally millions of different kinds of plants and animals. Why were there so many?

This diversity of design of organisms was as striking, in some regards, as their excellence of design, and even more striking were the patterns discernible within that diversity. Thousands of gradations and variations between organisms could be observed, but there were also huge gaps between them. There were birds and mammals that swam like fish, but none with gills; there were dogs of many sizes and shapes, but no dogcats or dogcows or feathered dogs. The patterns called out for classification, and by Darwin's time the work of the great taxonomists (who began by adopting and correcting Aristotle's ancient classifications) had created a detailed hierarchy of two kingdoms (plants and animals), divided into phyla, which divided into classes, which divided into orders, which divided into families, which divided into genera (the plural of "genus"), which divided into species.

36 AN IDEA IS BORN

What Is So Special About Species?
37

Species could also be subdivided, of course, into subspecies or varieties—

abstracting away from the grubby accidental properties of things to find their cocker spaniels and basset hounds are different varieties of a single species-, secret mathematical essences. It makes no difference what color or shape a dogs, or
Canis familiaris.

thing is when it comes to the thing's obeying Newton's inverse-square law of How many different kinds of organisms were there? Since no two organ-gravitational attraction. All that matters is its mass. Similarly, alchemy had isms are exactly alike—not even identical twins—there were as many dif-been succeeded by chemistry once chemists settled on their fundamental ferent kinds of organisms as there were organisms, but it seemed obvious that creed: There were a finite number of basic,
immutable
elements, such as the differences could be graded, sorted into minor and major, or
accidental
carbon, oxygen, hydrogen, and iron. These might be mixed and united in and
essential.
Thus Aristotle had taught, and this was one bit of philosophy endless combinations over time, but the fundamental building blocks were that had permeated the thinking of just about everybody, from cardinals to identifiable by their changeless essential properties.

chemists to costermongers. All things—not just living things— had two kinds The doctrine of essences looked like a powerful organizer of the world's of properties: essential properties, without which they wouldn't be the phenomena in many areas, but was it true of every classification scheme one particular
kind
of thing they were, and accidental properties, which were free could devise? Were there
essential
differences between hills and mountains, to vary within the kind. A lump of gold could change shape
ad lib
and still be snow and sleet, mansions and palaces, violins and violas? John Locke and others had developed elaborate doctrines distinguishing
real
essences from gold; what made it gold were its essential properties, not its accidents. With merely
nominal
essences; the latter were simply parasitic on the
names
or each kind went an essence. Essences were definitive, and as such they were words we chose to use. You could set up any classification scheme you timeless, unchanging, and all-or-nothing. A thing couldn't be
rather
silver or wanted; for instance, a kennel club could vote on a defining list of necessary
quasi-gold
or a semi'-mammal.

conditions for a dog to be a genuine Ourkind Spaniel, but this would be a Aristotle had developed his theory of essences as an improvement on mere nominal essence, not a real essence. Real essences were discoverable Plato's theory of Ideas, according to which every earthly thing is a sort of by scientific investigation into the internal nature of things, where essence imperfect copy or reflection of an ideal exemplar or Form that existed and accident could be distinguished according to principles. It was hard to timelessly in the Platonic realm of Ideas, reigned over by God. This Platonic say just what the
principled
principles were, but with chemistry and physics heaven of abstractions was not visible, of course, but was accessible to Mind so handsomely falling into line, it seemed to stand to reason that there had to through deductive thought. What geometers thought about, and proved be denning marks of the real essences of living things as well.

theorems about, for instance, were the Forms of the circle and the triangle.

From the perspective of this deliciously crisp and systematic vision of the Since there were also Forms for the eagle and the elephant, a deductive hierarchy of living things, there were a considerable number of awkward and science of nature was also worth a try. But just as no earthly circle, no matter puzzling facts. These apparent exceptions were almost as troubling to how carefully drawn with a compass, or thrown on a potter's wheel, could naturalists as the discovery of a triangle whose angles didn't quite add up to actually be one of the perfect circles of Euclidean geometry, so no actual 180 degrees would have been to a geometer. Although many of the taxo-eagle could perfectly manifest the essence of eaglehood, though every eagle nomic boundaries were sharp and apparently exceptionless, there were all strove to do so. Everything that existed had a divine specification, which manner of hard-to-classify intermediate creatures, who seemed to have por-captured its essence. The taxonomy of living things Darwin inherited was tions of more than one essence. There were also the curious higher-order thus itself a direct descendant, via Aristotle, of Plato's essen-tialism. In fact, patterns of shared and unshared features: why should it be backbones rather the word "species" was at one point a standard translation of Plato's Greek than feathers that birds and fish shared, and why shouldn't
creature with eyes
word for Form or Idea,
eidos.