by James Boyd

Created on: October 04, 2010

Among those who are not directly engaged in the physical sciences (physics, chemistry, biology, and so forth, in distinction from sociology, psychology, and other disciplines) there is a widespread misunderstanding of the term “theory”. Those who do not like the idea of evolution of living organisms, generally because it conflicts with religious belief, refer to evolution as “only a theory”. It is a theory, just like gravity and relativity are theories. It is also a fact, just like gravity and relativity.

Just like with gravity, there is no question of the existence of evolution of species, but there are a lot of theories as to mechanisms. The fossil record demonstrates clearly that living things have changed in many ways over time. Some species have become extinct and new species have arisen. Existing species have changed over time. Many of the specifics of those changes are unclear or unknown. Some have used the “missing link” concept as a method to deny the reality of evolution. There is, in fact, no problem that a link is missing. There are thousands of missing links. An organism is found as a fossil, and an earlier organism is clearly a precursor to that one. The changes from one to the other are too great to have happened all at once. Obviously, there is an intermediate form between the two, perhaps several of them. We just have not found them.

There are lots of theories about the mechanisms involved in evolution. There is a great deal of disagreement among scientists as to exactly how and why changes take place. There is no disagreement that changes actually do take place. So what we have here is evolutionary theory on the one hand and evolutionary fact on the other. We do not have to examine the fossil record to see the process of evolution. Every antibiotic-resistant microorganism is the result of natural selection. Evolutionary changes normally take very long periods of time but in this case we can watch the changes take place in just a few years.

Evolution is taught in schools because it is valid and important science, just like polymer chemistry or anatomy. There really is no controversy on this subject. Some people think they are entitled to impose their religious beliefs on scientific instruction. The Catholic Church came very close to executing Galileo for speculating that Earth might go around the sun, rather than the other way around. This was a curious error, since the Bible does not claim that the sun orbits the earth. They finally admitted their mistake, more than 300 years later.

If a school insists that students be taught the ideas of creationism, it can certainly do so, but it must be in a philosophy class, not a science class. Schools teach evolution because it is established scientific fact. It is no more a “theory”, in the sense some people seem to mean it, than the theory of gravitation or the germ theory of disease.   

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