Only A Theory

August 1995

By Bob Truett

Education is a family value! But education is not a Christian family value. It never has been. Christianity has almost unanimously opposed the teaching of evolution for more than a hundred years. Recently the more moderate Christian sects may have softened this opposition, but opposition from the less cerebral sects has increased and bristled.
Present efforts by the cross folks (pun intended) involve watering down the teaching of evolution by insisting it be taught as "only a theory" while also insisting on the teaching of something called creation science. An example is the recent action of the Alabama Department of Education in adopting a policy that public schools should not teach evolution as a fact. A dedicated and knowledgeable science teacher could use this action very effectively. The best weapon such a science teacher has is the presentation of Natural Selection as a theory. The use of this weapon requires that the science teacher must really understand what evolution is and what a theory is.

During my years as a zoologist and a zoo director in Alabama I was often asked "Do you believe in evolution?" The proper answer is "No, I do not." But this requires some explanation. I do not believe in the sun rising each morning, nor do I believe in oak trees growing from acorns. I do not believe in pussy cats licking the faces of their kittens nor in children laughing and playing pranks. "Believe in" implies faith in something for which there is not evidence. It is not necessary to believe in something which we can all see happening and which constantly manifests its own truth.

Stripped of all misconceptions, evolution is like the growth of an oak or the laughter of a child. It is a natural phenomenon that is abundantly apparent to everyone who has an open eye and an open mind. Thousands of persons have observed it and used it to their advantage. Evolution was observed and remarked in ancient times by Democritus, the laughing philosopher; by Heraclitus, the obscure philosopher; and by Aristotle, the father of zoology. Evolution simply means change. The growth of the oak and the laughter of the child are familiar examples of natural change that is going on around us at all times. Nature has no other phenomena that are more ubiquitous and easily observed than change.

There is really no such thing as the "Theory of Evolution." There are theories about how evolution works but these are not properly called the theory of evolution. The best known theories about how evolution works are those that were proposed by Charles Darwin. They are properly called the Theory of Natural Selection and the Theory of Sexual Selection.

The wise teacher also needs to know the meaning of the word theory. The average person might say "I have a theory that wearing red socks always brings me good luck." Used like this the word theory means a wild guess. Wild guesses are not the stuff of which science is made. In science a good, educated guess is called a hypothesis. The purpose of a hypothesis is to provide something to submit to experimentation and evidence in an attempt to learn the truth.

So what is a theory? A proper definition of a theory in science is this: A working explanation of natural phenomena based on available evidence. The three key words in this definition are working, explanation, and evidence. These are the keys to the strength of a scientific theory. And they are the keys to teaching evolution as a theory.

The first key is working. A valid theory in science must work. We still speak of the theorem ( theory) of Pythagoras. This theory has been used thousands of times in all kinds of construction and engineering. It is a theory because it works. Even in the study of music, when you get to the part about how music works it is called music theory. The Theory of Relativity worked when the atomic bomb was detonated.
The natural selection theory about evolution can be demonstrated to work in the school laboratory. Humans will do the selecting to produce changes instead of nature doing the selecting. Using ripe banana peels the teacher can show her students how to catch Drosophila melanogaster, the fruit fly. These flies are easy to maintain in captivity, they reproduce rapidly, and this is a very changeable species. Within one semester the teacher can help the students to use selective breeding to produce flies with no wings, or with green eyes, or other spectacular variations. On the farm you can start with Anas platyrhynchos, the mallard duck and in a few generations you can change your stock of ducks to white pekin ducks by selective breeding. For centuries farmers who never heard of evolution have used selection to produce new varieties of domesticated animals and even to produce entirely new species.

Many times when teaching about evolution I have been asked, "If living things changed in the past why aren't they changing now?" It is quite evident that many species are changing right now. There are changes occurring naturally in the fields and forests. In laboratories and on farms people are controlling the changes and causing them to happen more rapidly. The Theory of Natural Selection is valid because it works.

Let us ask that same question of creation science. If god created living things in the past why can't he create something alive now? I don't mean birth because that is life from life. It is stated that god created all kinds of living things from nothing or from dust. Try this in the laboratory. Put some sterile dust into an empty cage and let the kids pray about it. They should, of course, do their praying silently or in privacy at home. Suggest that they should use great faith, even invite their ministers to help them pray. Let them demonstrate whether creationism is a valid theory by a controlled experiment to see if god can create a mouse. Saying that god did it all in six days and won't do it again is not valid because the Bible has additional creation stories such as the special preparation of a great fish to swallow Jonah (Jonah 1:17). If god made a great fish then, he can make a small mouse now. Will it work?

The next key word is explanation. Theories about evolution explain hundreds of kinds of natural phenomena for which there is no other explanation. A few examples include Batesian and Mullerian mimicry, secondary sexual characteristics as spectacular sexual dimorphism, centers of distribution, and vestiges. Creationism has no explanation for any of these things. Ask the creationist why different species of butterflies mimic each other, or why the male Scarlet Tanager looks so different from the female, or why a human has a vestige of a tail. The best he can say is "because god made it that way." That explains nothing. If all humans were satisfied with such a non-explanation there would be no science at all and we would all still be living in the Dark Ages. The purpose of science is to explain nature.

The final key word is evidence. Evidence shows us the importance of theory. In science everything should always be taught as theory. Dogmatic statements of absolute truth are the antithesis of science. The theologian is absolutely certain he is right while the scientist always questions everything and looks for the evidence. In the past science, and everything else, was controlled by the church. So scientists had to believe, or at least pretend to believe, that god ordained laws which are in control of nature. In those days when a scientist explained something he called his explanation a law. Examples include the Law of Gravity and the Laws of Thermodynamics. We still speak of these as laws even though they have been drastically changed by modern theories. They were not really laws at all.

Actually there is no such thing as natural law. When a scientist finds an explanation for natural phenomena she should never call that explanation a law. Every scientific explanation that works and fits the available evidence is a theory and every theory should be subject to revision as more evidence becomes available. The very essence of science is its reliance upon the latest and best evidence. The strength of evolution is in the fact that it is theory. It is flexible enough to change when more and better evidence becomes available. The weakness of creationism is that it rests only on faith and not on evidence. Theologians can not rewrite the Genesis story to conform to new evidence. Therefore the creationist must constantly be hiding evidence, altering evidence, or trying to refute and explain away evidence which conflicts with the creation story.

That is the reason education is not a Christian family value. Throughout this land Christians fight bitterly against real education because it conflicts with their inflexible fables. They do not want evidence based teaching about evolution, nor about sex, nor about distant galaxies, nor about the religious views of those who wrote our constitution, nor about what persons of other religions believe, nor about the history of Christian mayhem, nor about the disaster of human overpopulation, nor about the tragic cost of criminalizing victimless behavior, nor about the religious causes of the war in Bosnia, etc. Christians like indoctrination, not education.

There are ways for any teacher to show her students how to use their brains in spite of the boundaries imposed by religion-controlled school boards. The way to make them really think about evolution is to emphasize that it is "only a theory." Then show them that only a theory is based on evidence, can be shown to work, and can explain the biology of the world around us.

Bob Truett is a Foundation member from Alabama, and is Zoo Director emeritus, Birmingham (AL) Zoo.

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