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Science Talk

Darwin's Influence on Modern Thought

On the 150th anniversary of the publication of Charles Darwin's Origin of Species, we review Darwin's influence on the the modern world, as analyzed by Ernst Mayr, one of the 20th century's most prolific evolutionary theorists. We review Mayr's July 2000 Scientific American article, "Darwin's Influence on Modern Thought". The original, complete essay is temporarily available free of charge at http://snipurl.com/darwinsciam

Steve: Hi, this is Steve Mirsky for Science Talk, the weekly podcast of Scientific American . November 24th is the 150th anniversary of the publication of certainly one of the most influential books of all time, Darwin’s Origin of Species. In 1999 Scientific American received an unsolicited manuscript from Ernst Mayr, one of the most important evolutionary biologists and evolutionary theorists of the 20th century. We published that article—I was privileged to be the editor of that article and in honor of the Darwin anniversary, we have released that article from behind the pay wall archive. It’s available free on our web site for the next 30 days. Ernst Mayr, M-A-Y-R. I had the privilege as I say of editing him and then interviewing him on his 100th birthday. He continued to publish after the age of 100; he finally passed away at the age of a hundred and a half in February of 2005. The article that we published appeared in the July 2000 issue of Scientific American . It was called "Darwin’s Influence on Modern Thought." As I say the entire article is available free on our web site. I’m not going to read the whole article, but I will read the whole introduction and then summarize the article for you.

"Darwin's Influence on Modern Thought" by Ernst Mayr

Clearly, our conception of the world and our place in it is, at the beginning of the 21st century, drastically different from the zeitgeist at the beginning of the 19th century. But no consensus exists as to the source of this revolutionary change. Karl Marx is often mentioned; Sigmund Freud has been in and out of favor; Albert Einstein’s biographer Abraham Pais made the exuberant claim that Einstein's theories "have profoundly changed the way modern men and women think about the phenomena of inanimate nature." No sooner had Pais said this, though, than he recognized the exaggeration. "It would actually be better to say 'modern scientists' than 'modern men and women,'" he wrote, because one needs schooling in the physicist’s style of thought and mathematical techniques to appreciate Einstein’s contributions in their fullness. Indeed, this limitation is true for all the extraordinary theories of modern physics, which have had little impact on the way the average person apprehends the world.

The situation differs dramatically with regard to concepts in biology. Many biological ideas proposed during the past 150 years stood in stark conflict with what everybody assumed to be true. The acceptance of these ideas required an ideological revolution. And no biologist has been responsible for more—and for more drastic—modifications of the average person's worldview than Charles Darwin.

Darwin's accomplishments were so many and so diverse that it is useful to distinguish three fields to which he made major contributions: evolutionary biology; the philosophy of science; and the modern zeitgeist. Although I will be focusing on this last domain, for the sake of completeness I will put forth a short overview of his contributions—particularly as they inform his later ideas—to the first two areas.

At this point Dr. Mayr goes into a section that is sub-headed 'A Secular View of Life' and he goes into four insights that serve as the foundation for Darwin’s founding of a new branch of the actual philosophy of science. For example, Darwin introduced historicity into science. Evolutionary biology, in contrast with physics and chemistry, is a historical science—the evolutionist attempts to explain events and processes that have already taken place. Dr. Mayr then goes into the four major contributions that Darwin made to the field of evolutionary biology. The first is the nonconstancy of species, or the modern conception of evolution itself. The second is the notion of branching evolution, implying the common descent of all species of living things. Up until 1859 all evolutionary proposals endorsed linear evolution, a teleological march toward greater perfection that had been in vogue since Aristotle. Darwin further noted that evolution must be gradual, with no major breaks or discontinuities and finally, he reasoned that the mechanism of evolution was natural selection and those four insights serve as the foundation for Darwin's founding of a new branch of the philosophy of science, a philosophy of biology because Darwin introduced history into science. Evolutionary biology, unlike physics and chemistry, is a historical science. The researcher is attempting to explain events and processes that have already taken place.

Dr. Mayr then goes into natural selection for a few paragraphs. The discovery of natural selection, by Darwin and by Alfred Russel Wallace, must be counted as an extraordinary philosophical advance because the principle remained unknown throughout more than 2,000-years of philosophy ranging from the Greeks to Hume, Kant and the Victorian era. The concept of natural selection has remarkable power for explaining directional and adaptive changes. It consists of two parts, a random generation of variation followed by a non-random selection among the variation. The truly outstanding achievement of the principle of natural selection is that it makes unnecessary the invocation of "final causes"—that is, any teleological forces leading to a particular end, nothing is pre-determined. By adopting natural selection, Darwin settled the several-thousand-year-old argument among philosophers over chance versus necessity. Change on the Earth is the result of both, the first step being dominated by randomness, the second by necessity. In the next section, subtitled, 'The Darwinian Zeitgeist,' Dr. Mayr goes into various aspects of Darwinism.

First, Darwinism rejects all supernatural phenomena and causations. The theory of evolution by natural selection explains the adaptedness and diversity of the world solely materialistically. It no longer requires God as creator or designer, although one is certainly still free to believe in God even if one accepts evolution. Second, Darwinism refutes typology. From the time of ancient Greeks, the general concept of the diversity of the world emphasized its invariance and stability. This view point is called typology, or essentialism. The members of each class were thought to be identical, constant, and sharply separated from the members of other essences.

Variation, in contrast, is nonessential and accidental. A triangle illustrates essentialism: all triangles have the same fundamental characteristics and are sharply delimited against quadrangles or any other geometric figures. An intermediate between a triangle and a quadrangle is inconceivable. Typological thinking, therefore, is unable to accommodate variation and gives rise to a misleading conception of, for example, human races. For the typologist, Caucasians, Africans, Asians or Inuits are types that conspicuously differ from other human ethnic groups. This mode of thinking leads to racism. Although the ignorant misapplication of evolutionary theory known as "Social Darwinism" often gets blamed for justifications of racism, adherence to the disproved essentialism preceding Darwin in fact can lead to the racist viewpoint.

Darwin completely rejected typological thinking and introduced instead the entirely different concept now called population thinking. All groupings of living organisms, including humanity, are populations that consist of uniquely different individuals. By rejecting the constancy of populations, Darwin helped to introduce history into scientific thinking and to promote a distinctly new approach to explanatory interpretation in science.

Darwin's theory of natural selection also made invocation of teleology unnecessary. From the Greeks onward, there existed a universal belief in the existence of a teleological force in the world that led to ever greater perfection. This "final cause" was one of the causes specified by Aristotle. Darwinism swept such considerations away.

Darwin does away with determinism. Laplace notoriously boasted that a complete knowledge of the current world and all its processes would enable him to predict the future to infinity. Darwin, by comparison, accepted the universality of randomness and chance throughout the process of natural selection. Despite the initial resistance by physicists and philosophers, the role of contingency and chance in natural processes is now almost universally acknowledged.

Darwin developed a new view of humanity and, in turn, ironically a new anthropocentrism. Of all Darwin's proposals, the one his contemporaries found most difficult to accept was that the theory of common descent applied to Man. For theologians and philosophers alike, Man was a creature above and apart from other living beings. The application of the theory of common descent to Man deprived man of his former unique position.

Ironically, though, these events did not lead to an end to anthropocentrism. The study of man showed that, in spite of his descent, he is indeed unique among all organisms. Human intelligence is unmatched by that of any other creature. Humans are the only animals with true language, including grammar and syntax. Only humanity, as Darwin emphasized, has developed genuine ethical systems and thus Darwin provided a scientific foundation for ethics. The question is frequently raised, as to whether evolution adequately explains healthy human ethics. Many wonder how, if selection rewards the individual only for behavior that enhances his own survival and reproductive success, such pure selfishness can lead to any sound ethics. The widespread thesis of social Darwinism, promoted at the end of the 19th century was that evolutionary explanations were at odds with the development of ethics.

We now know, however, that in a social species not only the individual must be considered—an entire social group can be the target of selection. Darwin applied this reasoning to the human species in 1871 in The Descent of Man . The survival and prosperity of a social group depends to a large extent on the harmonious cooperation of the members of the group, and this behavior must be based on altruism. Such altruism, by furthering the survival and prosperity of the group, also indirectly benefits the fitness of the group's individuals. The result amounts to selection favoring altruistic behavior.

Finally, Dr. Mayr summarizes the arguments he makes throughout the rest of the article. He writes, no educated person any longer questions the validity of the so-called theory of evolution, which we now know to be a simple fact. We will now get letters from various disgruntled listeners who contend that they are very well educated because they hold some degree from some renowned university and yet they still do not accept evolution. To those listeners, I recommend the scene near the end of The Wizard of Oz , when the wizard explains, what a diploma is and how it differs from having actual intelligence. Dr. Mayr goes onto say, I hope I have successfully illustrated the wide reach of Darwin's ideas. Yes, he established a philosophy of biology by introducing the time factor, by demonstrating the importance of chance and contingency, and by showing that theories in evolutionary biology are based on concepts rather than laws. But furthermore—and this is perhaps Darwin's greatest contribution—he developed a set of new principles that influence the thinking of every person: the living world, through evolution, can be explained without recourse to supernaturalism; essentialism or typology is invalid, and we must adopt population thinking, in which all individuals are unique (vital for education and the refutation of racism); natural selection, applied to social groups, is indeed sufficient to account for the origin and maintenance of altruistic ethical systems; cosmic teleology, an intrinsic process leading life automatically to ever greater perfection, is fallacious, with all seemingly teleological phenomena explicable by purely material processes; and determinism is thus repudiated, which places our fate squarely in our own evolved hands.

So that's a condensation of the full contents of the article, "Darwin's Influence on Modern Thought" by Ernst Mayr, which appeared in the July 2000 issue of Scientific American . Again it is now out from behind the pay wall, where it will remain for free access for the next 30 days. If you would like to access it, you can go to http://snipurl.com/darwinsciam, all one word, Darwin-s-c-i-a-m or just shop around on our website and you’ll find it prominently displayed. For Science Talk, the weekly podcast of Scientific American, I'm Steve Mirsky, thanks for clicking on us.

 [The above text is an exact transcript of the audio in the podcast.]

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