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Darwinism's Rules of Reasoning: Johnson, Phillip

Darwinism's Rules of Reasoning

Phillip E. Johnson
Professor of Law
University of California, Berkeley

This paper was originally delivered at a plenary session of the Southwestern Anthropological Association in Berkeley, California in April, 1992. It was subsequently published in the California Anthropologist and in Rivista di Biologia (1994) (in Italian and English). A similar lecture is included in the collection Darwinism: Science or Philosophy?(Buell & Hearn ed. 1994).

My starting point is a book review which Theodosius Dobzhansky published in 1975, critiquing Pierre Grassť's The Evolution of Life.(1) Grassť, an eminent French zoologist, believed in something which he called "evolution." So did Dobzhansky, but when Dobzhansky used that term he meant neo- Darwinism, evolution propelled by random mutation and guided by natural selection. Grassť used the same term to refer to something very different, a poorly understood process of transformation in which one general category (like reptiles) gave rise to another (like mammals), guided by mysterious "internal factors" which seemed to compel many individual lines of descent to converge at a new form of life. Grassť denied emphatically that mutation and selection have the power to create new complex organs or body plans, explaining that the intra-species variation that results from DNA copying errors is mere fluctuation, which never leads to any important innovation. Dobzhansky's famous work with fruitflies was a case in point. According to Grassť,

The genic differences noted between separate populations of the same species that are so often presented as evidence of ongoing evolution are, above all, a case of the adjustment of a population to its habitat and of the effects of genetic drift. The fruitfly (drosophila melanogaster), the favorite pet insect of the geneticists, whose geographical, biotropical, urban, and rural genotypes are now known inside out, seems not to have changed since the remotest times.(2)

Grassť insisted that the defining quality of life is the intelligence encoded in its biochemical systems, an intelligence that cannot be understood solely in terms of its material embodiment. The minerals which form a great cathedral do not differ essentially from the same materials in the rocks and quarries of the world; the difference is man's intelligence, which adapted them for a given purpose. Similarly, any living being possesses an enormous amount of "intelligence," very much more than is necessary to build the most magnificent of cathedrals. Today, this "intelligence" is called information, but it is still the same thing. It is not programmed as in a computer, but rather it is condensed on a molecular scale in the chromosomal DNA or in that of every other organelle in each cell. This "intelligence" is the sine qua non of life. Where does it come from?... This is a problem that concerns both biologists and philosophers, and, at present, science seems incapable of solving it.... If to determine the origin of information in a computer is not a false problem, why should the search for the information contained in cellular nuclei be one?(3)

Grassť argued that the Darwinists who dominate evolutionary biology have failed, due to their uncompromising commitment to materialism, to define properly the problem they were trying to solve. The real problem of evolution is to account for the origin of new genetic information, and it is not solved by providing illustrations of the acknowledged capacity of an existing genotype to vary within limits. Darwinists had imposed upon evolutionary theory the dogmatic proposition that variation and innovative evolution are the same process, and then had employed a systematic bias in the interpretation of evidence to support the dogma. Here are some representative judgments from Grassť's introductory chapter:

Through use and abuse of hidden postulates, of bold, often ill-founded extrapolations, a pseudoscience has been created..... Biochemists and biologists who adhere blindly to the Darwinist theory search for results that will be in agreement with their theories.... Assuming that the Darwinian hypothesis is correct, they interpret fossil data according to it; it is only logical that [the data] should confirm it; the premises imply the conclusions.... The deceit is sometimes unconscious, but not always, since some people, owing to their sectarianism, purposely overlook reality and refuse to acknowledge the inadequacies and the falsity of their beliefs.(4)

Dobzhansky's review summarized Grassť's central thesis succinctly:

The book of Pierre P. Grassť is a frontal attack on all kinds of "Darwinism." Its purpose is "to destroy the myth of evolution as a simple, understood, and explained phenomenon," and to show that evolution is a mystery about which little is, and perhaps can be, known.

Grassť was an evolutionist, but his dissent from Darwinism could hardly have been more radical if he had been a creationist. It is not merely that he built a detailed empirical case against the neo-Darwinian picture of evolution. At the philosophical level, he challenged the crucial doctrine of uniformitarianism, which holds that processes detectable by our present-day science were also responsible for the great transformations that occurred in the remote past.

According to Grassť, evolving species acquire a new store of genetic information through "a phenomenon whose equivalent cannot be seen in the creatures living at the present time (either because it is not there or because we are unable to see it)."(5) Grassť acknowledged that such speculation "arouses the suspicions of many biologists... [because] it conjures up visions of the ghost of vitalism or of some mystical power which guides the destiny of living things...." He defended himself from these charges by arguing that the evidence of genetics, zoology, and paleontology refutes the Darwinian theory that random mutation and natural selection were important sources of evolutionary innovation. Given the state of the empirical evidence, to acknowledge the existence of some as yet undiscovered orienting force that guided evolution was merely to face the facts. Grassť even turned the charges of mysticism against his opponents, commenting sarcastically that nothing could be more mystical than the Darwinian view that "nature acts blindly, unintelligently, but by an infinitely benevolent good fortune builds mechanisms so intricate that we have not even finished with analysis of their structure and have not the slightest insight of the physical principles and functioning of some of them."(6)

Dobzhansky disagreed with Grassť fundamentally, but he acknowledged at the outset that his French counterpart knew as much about the scientific evidence regarding animal evolution as anyone in the world. As he put it,

Now one can disagree with Grassť but not ignore him. He is the most distinguished of French zoologists, the editor of the 28 volumes of Traite de Zoologie, author of numerous original investigations, and ex- president of the Academie des Sciences. His knowledge of the living world is encyclopedic.

In short, Grassť had not gone wrong due to ignorance. Then where had he gone wrong? According to Dobzhansky, the problem was that the most distinguished of French zoologists did not understand the rules of scientific reasoning. As Dobzhansky summed up the situation:

The mutation-selection theory attempts, more or less successfully, to make the causes of evolution acces- sible to reason. The postulate that the evolution is "oriented" by some unknown force explains nothing. This is not to say that the synthetic...theory has explained everything. Far from this, this theory opens to view a great field which needs investigation. Nothing is easier than to point out that this or that problem is unsolved and puzzling. But to reject what is known, and to appeal to some wonderful future dis- covery which may explain it all, is contrary to sound scientific method. The sentence with which Grassť ends his book is disturbing: "It is possible that in this domain biology, impotent, yields the floor to metaphysics."

I began with the Dobzhansky/Grassť exchange to make the point that whether one believes or disbelieves in Darwinism does not necessarily depend upon how much one knows about the facts of biology. Belief that the various types of plants and animals were created by an extension of the kind of changes Dobzhansky's experiments brought about in fruitflies is at bottom a question of metaphysics. By metaphysics, I mean nothing more pretentious than the assumptions we all make about just which possibilities are worth considering seriously. For example, Pierre Grassť was willing to consider, and eventually to endorse, the possibility that the so-called "evolution in action" which the neo-Darwinists were observing is merely a variation within the limits of the existing genotype and not a source of genuine evolutionary innovation. To put the point in the language used by some contemporary biologists, Grassť proposed to "decouple macroevolution from microevolution." Such proposals have generally foundered on the inability to establish sufficiently credible distinctive macroevolutionary mechanisms. (For example, the widely publicized "new theory" of punctuated equilibrium turned out to be just a gloss upon Ernst Mayr's thoroughly Darwinian theory of peripatric speciation.) Grassť differed from the Darwinists in that he was willing to consider the possibility that science does not know, and may never know, how new quantities of genetic information have come into the world.

From Dobzhansky's viewpoint, to consider such a possibility would be to give up on science. As Dobzhansky saw it, we already know a lot about how plants and animal populations vary in the everyday world of ecological time. Dog breeders have given us St. Bernards and dachshunds, laboratory experiments have produced monstrous fruitflies, mainland species have differentiated after migrating to offshore islands, and the ratio of dark to light peppered moths in a population changed when the background trees were dark due to industrial air pollution. To be sure, none of these examples demonstrated the kind of innovation that Grassť had in mind. In the absence of a better theory, however, Darwinists consider it reasonable to assume that these observable variations illustrate the working in ecological time of a grand process that over geological ages created fruitflies and peppered moths and scientific observers in the first place. By making that extrapolation Darwinists create a scientific paradigm which can be fleshed out with further research, and improved. For a critic to suggest the possible existence of some factor outside the paradigm is helpful only if he can also propose a research strategy for investigating it. To Dobzhansky, therefore, Grassť's insistence that the sources of new genetic information might be a mystery to our science was pointless and harmful to the cause of science.

There is a political and religious dimension to the issues Grassť and Dobzhansky were debating which must also be considered. To say as Grassť did that, in the domain of creation, "biology, impotent, yields the floor to metaphysics" is to imply something important about the relative cultural authority of biologists and metaphysicians. Whatever that might mean in France, in the United States the scientific establishment has been in conflict over evolution for generations with the advocates of creationism. Although the scientists have won all the legal battles, there are still a lot of creationists around who are very much unconvinced with what the Darwinists are telling them. How many there are depends upon how "creationism" is defined.

The most visible creationists are the Biblical fundamentalists who believe in a young earth and a creation in six 24-hour days, and Darwinists like to give the impression that opposition to what they call "evolution" is confined to this group. In a broader sense, however, a creationist is any person who believes that there is a Creator who brought about the existence of humans for a purpose. In this broad sense, the vast majority of Americans are creationists. According to a 1991 Gallup poll, 47 per cent of a national sample agreed with the following statement: "God created mankind in pretty much our present form sometime within the last 10,000 years." Another 40 per cent think that "Man has developed over millions of years from less advanced forms of life, but God guided this process, including man's creation." Only 9 per cent of the sample said that they believed in biological evolution as a purposeless process not guided by God.

The evolutionary theory endorsed by the American scientific and educational establishment is of course the creed of the 9 per cent, not the God-guided gradual creation of the 40 per cent. Persons who endorse a God-guided process of evolution may think that they have reconciled religion and science, but this is an illusion produced by vague terminology. A representative Darwinist statement of "the meaning of evolution" may be found in George Gaylord Simpson's book bearing that title. In the words of Simpson:

Although many details remain to be worked out, it is already evident that all the objective phenomena of the history of life can be explained by purely naturalistic or, in a proper sense of the sometimes abused word, materialistic factors. They are readily explicable on the basis of differential reproduction in populations (the main factor in the modern conception of natural selection) and of the mainly random interplay of the known processes of heredity. ...Man is the result of a purposeless and natural process that did not have him in mind."(7)

"Evolution" is a vague term which can be used in a variety of senses. When it means only that a certain amount of natural change occurs in nature, it has no great philosophical consequences. What Simpson was describing was something much more specific, which I prefer to call the "blind watchmaker hypothesis," after the famous book by Richard Dawkins. According to Dawkins, "Biology is the study of complicated things that give the appearance of having been designed for a purpose."(8) Dawkins wrote his book to convince the public of something that Darwinians take for granted: The appearance of purposeful design in biology is misleading, because all living organisms, including ourselves, are the products of a natural evolutionary process employing random variation and natural selection. As Dawkins explains,

Natural selection is the blind watchmaker, blind because it does not see ahead, does not plan consequences, has no purpose in view. Yet the living results of natural selection overwhelmingly impress us with the appearance of design as if by a master watchmaker, impress us with the illusion of design and planning.(9)

We might therefore say that the watchmaker is not only blind, but unconscious.

The really important meaning of "evolution" is not that creation was a gradual process that required billions of years. It is that the process was supposedly undirected and purposeless. The prestige of the scientific establishment, and of the intellectual class in general, is heavily committed to the proposition that evolution -- in the blind watchmaker sense -- is either a fact, or a theory so well supported by evidence that only ignorant or thoroughly unreasonable people refuse to believe it. If the scientists ever had to retreat on this issue, the cultural consequences could be significant. Persons who now have a prestigious status as cultural authorities would be discredited, and the political and moral positions they have advocated might be discredited with them.

That is the fear of Michael Ruse, author of Darwinism Defended. Ruse proclaims proudly that Darwinism reflects "a strong ideology," and "one to be proud of." According to Ruse, most contemporary Darwinians "show a strong liberal commitment" in both their politics and their sexual morality.(10) Advocates of creation, on the other hand, want to restore a "morality based on narrow Biblical lines" with respect to marriage and sexual behavior. Ironically Darwinism, which has at so often been associated with ideologies of racial superiority, eugenics, and unrestrained competition, is currently enlisted in the fight against that trinity of political incorrectness: racism, sexism, and homophobia. Ruse concludes his book with these stirring lines "Darwinism has a great past. Let us work to see that it has an even greater future."(11)

Such statements are equivalent to the claims of creation-science advocates that to doubt the Genesis account is to open the floodgates for all kinds of immorality. I think that Michael Ruse and Henry Morris are both right to insist that cultural acceptance of Darwinism has had important consequences for politics and morality. Recognition of this factor, however, also has important implications for how we should regard Darwinism's rules of reasoning. Are those rules designed to protect a cherished doctrine from scientific criticism -- criticism that might, wittingly or unwittingly, give aid and comfort to persons who want to deprive the Darwinist establishment of its cultural authority? If physicists were to start to proclaim that belief in the Big Bang has had wonderful political and moral consequences, and we must all work to see that the Big Bang has a wonderful future, surely we would begin to wonder about their objectivity.

Darwinism's rules of reasoning not only protect the cultural authority of Darwinists. They also permit Darwinist writers to take the mutation/selection mechanism for granted even when they are describing evidence which directly contradicts it. This feat of intellectual contortionism is strikingly illustrated by Stephen Jay Gould's book, Wonderful Life. Gould's bestseller adds a great deal to our knowledge of the "Cambrian explosion," meaning the sudden appearance of the invertebrate animal phyla, without visible ancest