Arguing for Evolution

On August 11, 1999, the Kansas State Board of Education voted six-to-four to remove references to cosmology and evolution from the State's education standards and assessments.  The Board's decision does grave disservice to the students and teachers of the State of Kansas, as well as to science and religion everywhere.

        Students need to study the empirical evidence and concepts central to scientific knowledge to become informed and responsible citizens and to acquire suitable job skills and professional training. The Board's decision places Kansas students at a competitive disadvantage in their education and job qualification and impairs the recruitment of capable and inspired teachers, who will abhor being inhibited from teaching their best knowledge.


        Opponents to teaching the theory of evolution declare that it is only a theory and not a fact; and that science relies on observation, replication and experimentation, but nobody has seen the origin of the universe or the evolution of species, nor have these events been replicated in the laboratory or by experiment.

        When scientists talk about the "theory" of evolution, they use the word differently than people do in ordinary speech.  In everyday speech, a theory is considered to be an imperfect fact, as in "I have a theory as to what caused the explosion of TWA flight 800."  In science, however, a theory is based on a body of knowledge.

        According to the theory of evolution, organisms are related by common descent.  There is a multiplicity of species because organisms change from generation to generation, and different lineages change in different ways. Species that share a recent ancestor are therefore more similar than those with remote ancestors. Thus, humans and chimpanzees are, in configuration and genetic make-up, more similar to each other than they are to baboons or to elephants.

        Scientists agree that the evolutionary origin of animals and plants is a scientific conclusion beyond reasonable doubt.  They place it beside such established concepts as the roundness of the earth, its rotation around the sun, and the molecular composition of matter.  That evolution has occurred, in other words, is a fact.

        How is this factual claim compatible with the accepted view that science relies on observation, replication and experimentation, even though nobody has observed the evolution of species, much less replicated it by experiment? What scientists observe are not the concepts or general conclusions of theories, but their consequences. Copernicus' heliocentric theory affirms that the Earth rotates around the Sun.  Nobody has observed this phenomenon, but we accept it because of numerous confirmations of its predicted consequences. We accept that matter is made of atoms, even though nobody has seen them, because of corroborating observations and experiments in physics and chemistry.  The same is true of the theory of evolution. For example, the claim that humans and chimpanzees are more closely related to each other than they are to baboons leads to the prediction that the DNA is more similar between humans and chimps than between chimps and baboons.  To test this prediction, scientists select a particular gene, examine its DNA structure in each species, and thus corroborate the inference.  Experiments of this kind are replicated in a variety of ways to gain further confidence in the conclusion. And so it is for myriad predictions and inferences between all sorts of organisms.

        Not every part of the theory of evolution is equally certain. Many aspects remain subject to research, discussion and discovery. But uncertainty about these aspects does not cast doubt on the fact of evolution.  Similarly, we do not know all the details about the configuration of the Rocky Mountains and how they came about, but this is not reason to doubt that the Rockies exist.

        The theory of evolution needs to be taught in the schools because nothing in biology makes sense without it.  Modern biology has broken the genetic code, developed highly productive crops, and provided knowledge for improved health care.  Students need to be properly trained in biology in order to improve their education, increase their chances for gainful employment, and enjoy a meaningful life in a technological world.


        Does the teaching of evolution pose a threat Christianity or to other religions? This question can be answered in two parts.  I would first address those who profess a materialistic philosophy and seek to ground it in the theory of evolution and other scientific claims.  They point out the great success of science in explaining the workings of the universe, and claim there is no room for other kinds of explanations-no room for values, morality, or religion.  We may grant these persons their right to think as they wish, but they have no warrant whatsoever to ground this materialistic philosophy in the achievements of science. Science seeks material explanations for material processes, but it has nothing definitive to say about realities beyond its scope.  Science is a way of acquiring knowledge about ourselves and the world around us, but it is not the only way. We acquire knowledge in many other ways, such as literature, the arts, philosophical reflection, and religious experience.  Scientific knowledge may enrich aesthetic and moral perceptions, but these subjects transcend science's realm.

        Scientific knowledge cannot contradict religious beliefs, because science has nothing to say for or against religious realities or religious values. Many religious authorities have made this point. Catholic, Lutheran and other Protestant bishops have joined Jewish and other religious leaders in denying that the theory of evolution contradicts or threatens their religious beliefs.

There are, however, believers who see the theory of evolution and scientific cosmology as contrary to the creation narrative of the Book of Genesis.  We may grant these believers their right to think this, just as at the other extreme of the spectrum we grant materialists their right to deny spiritual or religious values.  But, as the counterpoint to what I said above, I will aver that Genesis is a book of religious revelations, not a textbook of astronomy or biology.  Pope John Paul II has made the point:  "The Bible speaks to us of the origins of the universe and its makeup, not in order to provide us with a scientific treatise, but in order to state the correct relationship of man with God and the universe.  Sacred Scripture wishes simply to declare that the world was created by God, and in order to teach this truth, it expresses itself in the terms of the cosmology in use at the time of the writer. The sacred book likewise wishes to tell men that the world was... created for the service of man and the glory of God. Any other teaching about the origin and makeup of the universe is alien to the intentions of the Bible, which does not wish to teach how heaven was made but how one goes to heaven."  St. Augustine had made the point many centuries earlier: "In the matter of the shape of heaven the sacred writers did not want to teach men facts that would be of no avail for their salvation."

The point made by St. Augustine and the Pope is that it is a blunder to mistake the Bible for an elementary textbook of astronomy, geology, and biology.  Instead, it is possible to believe that God created the world while also accepting that the planets, mountains, plants and animals came about, after the initial creation, by natural processes.  I can believe that I am God's creature without denying that I developed from a single cell in my mother's womb by natural processes. This is the second part of my answer to the purported opposition between scientific conclusions and religious beliefs. They do not stand in contradiction; they concern different sorts of issues, belong to different realms of knowledge.


There is one more point I wish to make in response to those who defend the special creation of the species on the grounds of their design, which they see as necessarily a product of Divine Intelligence.  The point is that not only can natural selection account for the "design" of organisms, but also it amounts to blasphemy to attribute it to God's special action.

Consider the human jaw.  We have too many teeth for the jaw's size, so that wisdom teeth need to be removed and orthodontists make a decent living straightening the other teeth.  Would we want to blame God for such defective design? A human engineer could have done better.  Evolution gives a good account of this imperfection. Brain size increased over time in our ancestors, and the remodeling of the skull to fit the larger brain entailed a reduction of the jaw. Evolution responds to the organisms' needs through natural selection, not by optimal design, but by "tinkering" as it were, by slowly modifying existing structures.  Consider now the birth canal of women, much too narrow for easy passage of the infant's head, so that thousands upon thousands of babies die during delivery.  Surely we don't want to blame God for this defective design or for the children's deaths.  Science makes it understandable, a consequence of the evolutionary enlargement of our brain. Females of other animals do not experience this difficulty.

One more example: why are our arms and our legs, which are used for such different functions, made of the same materials, the same bones, muscles and nerves, all arranged in the same overall pattern? Evolution makes sense of the anomaly.  Our remote ancestors' forelimbs were legs.  After our ancestors became bipedal and started using their forelimbs for functions other than walking, these became gradually modified, but retained their original composition and arrangement.  Engineers start with raw materials and a design suited for a particular purpose; evolution can only modify what is already there.  An engineer who would design cars and airplanes, or wings and wheels, using the same materials arranged in a similar pattern, would surely be fired.  The defective design of organisms could be attributed to the gods of the ancient Greeks, Romans and Egyptians, who fought with one another, made blunders and were clumsy in their endeavors.  But, in my view, it is not compatible with a special action by the omniscient and omnipotent God of Judaism, Christianity, and Islam.

        There is no need for warfare between science and religion. It is unfortunate that some would deprive students of a proper scientific education on religious grounds, as it is unfortunate that some seek in science arguments to negate the legitimacy of religious beliefs.

Bibliographical note

John Paul II's quotation is from his address to the Pontifical Academy of Sciences on 3 October 1981.  In his address to the Pontifical Academy of Sciences on October 22, 1996, he again deplored interpreting the Bible's teachings as scientific rather than religious, and said: "[N]ew knowledge has led us to realize that the theory of evolution is no longer a mere hypothesis.  It is indeed remarkable that this theory has been progressively accepted by researchers, following a series of discoveries in various fields of knowledge.  The convergence, neither sought nor fabricated, of the results of work that was conducted independently is in itself a significant argument in favor of this theory."  (L'Osservatore Romano, 23 October 1996.)

St. Augustine's quotation is from The Literal Meaning of Genesis, Book 2, ch. 9. In Book 3, ch. 14, he makes the remarkable statement that many animal species were not present from the beginning, but appeared later "each according to its kind and with its special properties," as a result of a natural power "present from the beginning in all living bodies." One can surmise that Augustine would have found no conflict between the theory of evolution and the teachings of Genesis, which are the subject of his commentary.

 "Arguing For Evolution" by Francisco Ayala is reprinted with permission from "The Science Teacher," February 2000 (vol. 67, no. 2), pp. 30-32.


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