Michael Ruse is, somewhat unusually, a professor of both philosophy and zoology. In this book he looks at how evolutionary thought developed between 1830 and 1875. The book was originally published in 1979; the text has not been revised for the new edition but Ruse has included an Afterword in which he looks at new research that has come out in the intervening years. There has been an immense outpouring of publications about Darwin and the Darwinian Revolution since his book first appeared but it still merits an honourable place, both for its insights and for its readability, enhanced by touches of humour. To some extent it covers the same territory as Peter Bowler's Evolution: the history of an idea, but its focus is narrower in time while providing more in-depth discussion of the philosophical and religious ideas of Darwin's contemporaries.
Ruse is particularly good on the personalities of those involved. They were indeed a colourful bunch. They included William Whewell, Adam Sedgwick, Baden Powell (father of the founder of the Scout movement), John FW Herschel (son of the famous astronomer William Herschel), Charles Lyell, Richard Owen, and Charles Babbage, better known for his invention of the calculating engine, as well as Charles Darwin and Thomas Henry Huxley. Many of these, especially those belonging to the older generation, were clergymen; it was impossible to be a Fellow of a college at Oxford or Cambridge at the time unless one was in Holy Orders. This inevitably coloured their views on evolution, though not always in the way one might expect.
Popular accounts of the debate about evolutionary thought in the nineteenth century often convey the impression of a straightforward conflict between secularism and religion, in which scientific secularism emerged triumphant. As Ruse makes clear, this is a considerable over-simplification: the relation between religion and science was in fact very complex, and in some ways religion actually helped the cause of science. Other factors, philosophical and social, were also involved, and Ruse's claim is that all of these elements have to be given due weight if the development of evolutionism is to be understood.
That profound changes in intellectual attitudes occurred in the nineteenth century there can be no doubt. In 1844, when Robert Chambers published his Vestiges of the Natural History of Creation, in which he argued the case for organic evolution, hardly any serious scientists accepted its main message, but when Charles Darwin published The Origin in 1859 his main claim was quickly accepted by almost all scientists concerned with the origin of organisms. In part, this was a consequence of the difference in the scientific standing of the two authors, but there were other reasons as well and it is these that Ruse seeks to elucidate.
First, there were scientific reasons to accept evolution. It made sense of the geographical distribution of species, such as finches and tortoises on the Galapagos Islands, which Darwin described and which was hard to explain on any other assumption. Also, by the 1860s more was known about the fossil record than had been known in 1844, and it was becoming increasingly difficult to doubt that progression had occurred during geological time. Darwin was therefore able to draw on a more ample arsenal of scientific facts; indeed, he had made significant contributions to that arsenal himself.
Of course, Darwin was not merely advocating evolution as a process, he put forward a mechanism by which it could occur. Chambers had not provided a plausible cause for evolution, but Darwin did, with his mechanism of natural selection. However, this idea had its problems: estimates of the age of the earth seemed not to allow enough time for evolution, and many people doubted if natural selection could be powerful enough to produce new species as opposed to mere variations. Even T.H.Huxley, "Darwin's bulldog", was relatively uninterested in natural selection and tended to downplay its importance. But field naturalists such as Henry Walter Bates found it invaluable as an explanation for insect mimicry and his work was cited by Darwin in later issues of The Origin.
The second area of change was in philosophy. Many of the older scientists were idealists, Platonists, who favoured the view that species were immutable Types. Huxley, on the other hand, was not a Platonist and criticized his older colleagues on that ground. This change was both a cause and a consequence of other changes, in religious thought and in society at large, that were occurring at this time. Ruse points to innovations in the educational system leading to a reduced emphasis on the Classics and a weakening in the influence of religion. Not surprisingly in view of his professional background, Ruse pays considerable attention to the philosophical principles espoused by the main participants in the debate. There was a prevailing assumption, to which Darwin himself largely subscribed, that physics, and especially astronomy, provided the explanatory model to which other sciences ought to aspire.
The third class of change affected religion. Chambers had been attacked on religious grounds: he was held to have threatened the special position of man and to have left no room for God's design. Similar criticisms were made of Darwin but less strongly. However, religion, Ruse believes, also helped Darwinism. The argument from design prepared people's minds for evolutionism, while thinkers such as Baden Powell thought of God as working through unbroken natural laws rather than through miracles.
In the 1830s and 1840s religion was a thorny problem for many people. Partly this was a reaction to science; Ruse thinks that the attempt to reconcile science and revelation was a particularly British preoccupation (as perhaps it still is). And conventional religion was also under threat from another source: German Biblical criticism. As a result, some prominent clergymen, including Lyell, had moved a long way towards Deism (natural as opposed to revealed religion).
Lyell is a particularly interesting figure in the present context. His Principles of Geology accompanied Darwin on his voyage in the Beagle and had a major influence on his thought. As a Deist, he was unhappy about introducing miracles to explain the origin of species; unlike Whewell, who thought it was compatible with science. Ruse sums this up neatly by saying that Lyell wanted a world left alone by God, in which organisms struggle for survival under the threat of extinction, whereas Whewell wanted to see God hovering protectively over his creation.
Fourthly, there were social and political influences. In the 1830s there was a real fear that revolution might spread to Britain from abroad; by 1860 this was no longer the case. And in the second half of the century it was possible for a man to become a professional scientist without private means and without taking Holy Orders: a change that helped to weaken the influence of religion.
It is difficult to describe all these developments without falling into circularity, because each type of cause influenced, and was influenced by, the others, but in a way this is precisely Ruse's point. He insists that there were many different threads intertwining among themselves and that it is misleading to oversimplify the argument by concentrating on what appear to be the "real" issues. I think he makes a convincing case for this claim. He finds no need to alter his views in this reissue of the book, as he explains in the Afterword, though I was glad to see that he softens his earlier criticism of Huxley, whom I have always rather liked. I was even more glad to read that he strongly dissociates himself from "social constructivism" in the history of science. He states emphatically that "Charles Darwin was telling us real truths about a real world". There is no question of organic evolution being a human-created fiction.
Ruse is, however, rather despondent about the present position of evolution studies as an academic discipline. He is concerned that evolution is often seen to be "popular science" and is usually linked with ecology, instead of being accorded the importance it deserves. There is indeed a paradox here, which Ruse perhaps fails to bring out fully. He mentions that in the USA today there are ten times as many departments of molecular biology as of evolution, but he does not point out that it is impossible to understand molecular biology adequately unless it is seen in an evolutionary context. The interesting question, therefore, is why this fact is not always recognized.
Much the same failure to take account of Darwinism exists within medicine. The origins of many diseases can only be understood from an evolutionary viewpoint (Charlton BG; Nesse RM, Williams GC). Immunology, which is basic to modern medicine, is an evolutionary science through and through (Tauber AI). And yet "Darwinian medicine" is hardly a dozen years old; even today, few doctors are familiar with the term. There is a sense in which the Darwinian revolution has still hardly begun.