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 Grassé's The Evolution of Life.(1) Grassé, 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. Grassé 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. Grassé 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 Grassé,

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)

Grassé 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)

Grassé 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 Grassé'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 Grassé's central thesis succinctly:

The book of Pierre P. Grassé 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.

Grassé 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.