The Philosophical Breakfast Club (59 page)

After reading Sedgwick’s review, Darwin admitted to Lyell, “It is a grand piece of argument against mutability of species, and I read it with fear and trembling.”
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Darwin was determined that any book of his would
not meet the same fate. He would design his book explicitly to meet the conditions for good inductive science that the experts of the day, Whewell and Herschel, had set out in their works, so that no such criticisms could be made of his work. It would take him nearly fifteen years to achieve that goal. (Darwin was still worrying right before his book was published; he wrote to Asa Gray, the American botanist and a strong supporter of Darwin’s work, that he still felt that “my work will be grievously hypothetical, and large parts by no means worthy of being called induction, my commonest error being probably induction from too few facts.”
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)

Darwin had long been impressed with Herschel’s and Whewell’s views of science. Reading Herschel’s book on scientific method when he was an undergraduate at Cambridge “stirred up inside me a burning zeal to contribute to science,” Darwin recalled.
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Whewell also served as a kind of scientific mentor to Darwin. Darwin attended John Henslow’s botany lectures in the company of Whewell, who probably recommended Herschel’s book to his younger colleague. Darwin respected the breadth and depth of Whewell’s knowledge, calling him one of the “best conversers on grave subjects to whom I have ever listened.”
⁴⁴
He was particularly impressed by Whewell’s work on the tides, believing that he “will always rank as one of the great investigators” of the topic.
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Darwin was less awed by Whewell’s Bridgewater Treatise; one of his notes on that text mocks Whewell for his claim that the length of the solar day is twenty-four hours, with twelve hours of night, because that arrangement best suits man’s need for sleep: “whole universe so adapted!!! And not man to planets—instance of arrogance!!!”
⁴⁶
But Darwin’s close reading of the Bridgewater Treatise had led him to realize that he had to show how his theory could offer an alternative explanation for the fitness of organisms to their environment, an explanation that relied neither on pure chance nor on God’s special creation. Whewell’s more sophisticated version of the argument from design was the one Darwin knew he had to take aim at, not Paley’s more simplistic treatment. Darwin would ultimately sandwich his disagreeable view between slices of the digestible, law-based version of natural theology endorsed by Whewell: he had a quote from Whewell’s Bridgewater Treatise on the frontispiece of the book (reminding his readers that “with regard to the material world, we can at least go so far as this—we can perceive that events are brought about not by insulated interpolations of Divine Power, exerted in each particular case, but by the establishment of general laws”), and he ended
it with a stirring passage suggesting that God was a Divine Lawmaker, just as Whewell had suggested: “There is grandeur in this view of life,” Darwin tried to convince his audience, “having been originally breathed by the Creator into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been and are being, evolved.”
⁴⁷

Whewell’s writings on scientific method, along with Herschel’s, served as a model for Darwin in constructing his argument for evolution by natural selection. He read Whewell’s
History of Inductive Sciences
at least twice—his diary indicates that he had gone through the book carefully for a second time in the fall of 1838. In a letter to Whewell the following spring, Darwin told him that “to see so clearly the steps by which all the great discoveries have been come to is a capital lesson to every one, even to the humblest follower of science and I hope I have profited by it.”
⁴⁸
Two years later, after reading Herschel’s review of the
History
and the
Philosophy of the Inductive Sciences
in the
Quarterly Review
, Darwin made a note to himself: “
I must study
Whewell on Philosophy of Science.”
⁴⁹

Darwin finally published his theory in 1859, spurred on by learning that another man, Alfred Russel Wallace, had come to a very similar theory as his—Wallace had realized both the importance of the struggle for existence and the introduction of new species it helps bring about. Darwin’s hand was forced, lest he lose his standing as the “discoverer” of the theory. He did not want to end up like John Couch Adams, forever living with the indignity of taking second place in the race to scientific truth. Darwin set to work and quickly wrote his revolutionary work,
On the Origin of Species
. His book can be seen as encoding Whewell and Herschel’s philosophy of science, especially what they had considered the strongest type of evidence for a scientific theory—what Whewell had dubbed
consilience
.

Both Herschel and Babbage had already discussed the power of this kind of evidence in their works: Herschel in the
Preliminary Discourse
, and Babbage in his
Ninth Bridgewater Treatise
.
⁵⁰
But Whewell gave the most detailed and interesting description of it in his
Philosophy of the Inductive Sciences
. “The Consilience of Inductions,” he explained, “takes place when an Induction, obtained from one class of facts, coincides with an Induction obtained from another different class.”
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Whewell’s favorite example of a consilient theory was Newton’s law of universal gravitation. In the
Mathematical Principles of Natural Philosophy
, where he announced
his discovery, Newton described how his study of the moons of Jupiter showed him that they were retained in their orbits around Jupiter by a force directly proportional to the products of the masses of the moons and Jupiter, and inversely proportional to the squares of the distances of the centers of the moons from the center of the planet. His study of the earth’s moon led to the same conclusion, that our satellite was held in its orbit by a force directly proportional to the product of the masses of the moon and earth, and inversely proportional to the square of the distance between the center of the moon and the center of the earth. Similarly, Newton’s study of the planets led to the conclusion that the planets, too, were retained in their orbits around the sun by a force directly proportional to the product of the masses and inversely proportional to the square of the distances of the centers of the planets to the center of the sun. Newton found, as well, that falling bodies are governed by a force directly proportional to the product of the masses of the bodies and the earth, and inversely proportional to the square of the distances of the bodies from the center of the earth.

All these different kinds of phenomena “leapt to the same point,” as Whewell put it: they each led to the same inverse-square law of attraction, leading Newton to his universal law of gravitation, which generalized this inverse-square force of attraction even further:
every
object in the universe attracts every other object with a force directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers. Newton then used this law to account for other phenomena, such as some facts about the motion of the tides. What Newton’s law did so brilliantly was to provide a causal unification of the forces of the universe, by bringing together phenomena previously thought of as distinct, showing that they all fall under the same law and have the same cause. Who before Newton thought that the motion of planets and satellites, falling objects, and the tides were all governed by the same force? Consilience shows us, Whewell argued, that the theory is very probably true, because it would be highly unlikely for a false theory to causally unify so many diverse phenomena.

Darwin saw that his theory would be the most strongly supported if he could show how it causally unified facts in many different fields, the way Newton’s law of universal gravitation did. He set out to fulfill this requirement, observing, experimenting, reading, and collecting data of all sorts. He began to breed pigeons obsessively, seeking observational
evidence for the inheritance of characteristics such as black wing feathers or heads of diverse shapes. He studied barnacles, inquiring into every known species of that crustacean, finding tiny adaptations that made one variety more successful than another in surviving its watery environment. The study of barnacles revealed to Darwin the high rate of variation that occurred in nature. (He spent so many hours, for so many years, on barnacles, that his children grew up believing that all fathers studied barnacles. “Where does your father do his barnacles?” one of his sons asked a young friend.)
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When he finally published the
Origin of Species
, it was packed with evidence, showing how his theory of evolution by natural selection provided a causal explanation for many different kinds of facts: those in the realms of classification of organisms (how they are sorted into groups), biogeography (patterns of distribution of species), comparative anatomy (homologous structures), paleontology (especially the fossil record, which shows both the extinction of old species and the arrival of new ones), and other areas. For instance, his theory provided a causal explanation for the observed cases of homological structures, such as the wing of a bat and the arm of man, which share a similar arrangement of bones. According to Darwin’s theory, homologous structures descend from a common ancestor, and since the changes that eventually result in the branching off of different species happen gradually, the main pattern of composition remains the same.
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Similarly, the fitness of species to their environments could be causally explained by the theory; individuals
not
well suited to survive in an environment would tend to die before having the chance to reproduce, and so they would be “weeded out,” as it were, leaving only individuals that are well suited to the environment. The species
Ursus maritimus
(polar bear) has white fur not because God made it that way, but because any bears with black fur born in the snowy Arctic are hunted down by their predators and killed before reaching the age of reproduction; only white bears have the chance to survive and reproduce, creating more white bears.

When the
Origin of Species
was first published, it was a literary and scientific event. The first edition sold out on its very first day, November 24, 1859. Everyone, it seemed, was reading and talking about it. George Eliot told a friend, using the terminology from Whewell’s
History of the Inductive Sciences
, “We have been reading Darwin’s Book … just now: it makes an epoch.”
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At the same time, Darwin’s greatest fears were realized: many of the reviews lambasted the author for his faulty scientific method. Sedgwick and Owen, for example, took Darwin to task for having “departed from the true inductive track.”
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In later editions of the book, Darwin emphasized more strongly the consilience of the theory, how it explains such a wide variety of types of facts, arguing that “I cannot believe that a false theory would explain … the several large classes of facts above specified.”
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N
OT SURPRISINGLY, GIVEN
the view of God as a computer programmer that he had been endorsing for decades now, Babbage was an early convert to evolutionary theory. He had no difficulty accepting the idea that God set up His Creation so that species would evolve, naturally, without any further intervention on His part. In the opening pages of his
Passages from the Life of a Philosopher
, published in 1864, Babbage noted that Darwin’s view of our origin is “philosophic” (that is, scientific) but “unromantic.” Yet he claimed that the “continual accumulation of evidence” had convinced him that it was probably true.
⁵⁷

But Darwin was more concerned with what Herschel and Whewell would think. The year before, he had seen the two elder statesmen of science at the British Association meeting in Leeds; Whewell, at sixty-four, now white-haired and said to be “grow[ing] squarer and more Bishop-like than ever,” had been the head of the Mathematical and Physical Sciences section; Herschel, increasingly frail at sixty-six, had presided over the Chemical section; and Darwin himself had been the chair of the Zoology and Botany section.
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He sent both men copies of the book as soon as it came off the printing press. In the letter accompanying Herschel’s copy, Darwin acknowledged his debt to the older man: “Scarcely anything in my life made so deep an impression on me” as the
Preliminary Discourse
. “It made me wish to try to add my mite to the accumulated store of natural knowledge.”
⁵⁹
Although he had, Darwin believed, followed their prescriptions for gathering and presenting the best kind of evidence for a scientific theory, neither Herschel nor Whewell enthusiastically accepted evolutionary theory. Herschel’s immediate response was the most cutting: he referred to evolution by natural selection as “the law of higgedly-piggedly” (that is, a random mess), which particularly pained Darwin when he heard of it. Later, in a note added to an 1861 reprinting of his
Physical Geography
—which had originally appeared in the
Encyclopaedia Britannica
in 1859—Herschel explained that he could not accept “the principle of arbitrary and casual variation and natural selection as sufficient account, per se, of the past and present organic world.” It would be, he said, just like asserting that a process of randomly combining words could result in the works of Shakespeare or Newton’s
Principia
. Rather, Herschel argued, “an intelligence, guided by a purpose, must be continually in action to bias the directions of the steps of change.” As in his earlier letter to Lyell, Herschel continued to assert that “we do not mean to deny that such intelligence may act according to law.”
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