Tag Archives: rationalism

Why Is Evolution A Theory?: A Deeper Understanding of Scientific Jargon


What’s the scoop?

By far the most common, and perhaps the most fallacious, argument against the existence of evolution is that “it is only a theory.” I doubt that I am the first to correct criticizers nor do I have any reason to believe that they will listen to me any more than they would to their biology teacher or, say, Richard Dawkins.

Nevertheless, in order to discuss more-detailed aspects of evolution on this blog in the future, I feel as though I must set a foundation by defining some basic scientific terms and how they relate to evolution, even before I go in depth as to what evolution really is.

So let’s get started, shall we?

What is a scientific theory?

Many anti-evolutionists get stuck at this first point. The word “theory” has an every day use, typically when someone speculates something without much support. For instance, I could have a “theory” that my cat is eating my donuts in the middle of the night, because my donuts keep disappearing. Well, in mild scientific terms this is closer to a predictiona reasonable guess based on preexisting knowledge, called a hypothesis. The hypothesis here is that my cat likes donuts and is a sneaky little fur-ball, so it is reasonable to predict that she is stealing my donuts. It is not until I find evidence, such as video-taping her eating them or smelling the glaze on her breath, to support my prediction and hypothesis that they can be taken seriously.

That process of catching my cat in the act and drawing a conclusion forms the basis of the scientific method: question, research, hypothesize, predict, research more, design a test, perform the test, observe, analyze results, research more, discuss results, conclude, review, allow others to review, research even more, revise, and usually repeat several times before any acceptance. In addition, your test should be reproducible, observable, quantifiable, and capable of being discredited by independent sources. This method is a technique and philosophy that is grounded in the very basal level of logic and rationalism, which use reason as a source of validity.

Whereas a “theory” is commonly used to express an untested idea, a scientific theory is essentially an over-arching group of concepts and conclusions that have been repeatedly tested, analyzed, and accepted to describe observable phenomena. These phenomena are events, facts, behaviors, and processes of the universe, and scientific theories are a means to explain, predict, and master these. We can observe these phenomena, and we hold them to be as true so as long as our model of reality is true (I’ll leave discussions of reality to the physicists and philosophers).

So, when you hear the phrase “the theory of evolution,” the theory there is a scientific theory, not the “theory” used in an every day sense, one that acts like a prediction that is not yet tested. It’s not as though scientists had a big conference one day, wrote up this long paper that explains fossils, biodiversity, and whatnot, had lunch, and left it at that. No. The theory of evolution has been changed, revised, argued, and criticized by thousands, maybe millions, of independent sources and experiments, even well-before Charles Darwin wrote On the Origin of Species in 1859. All of these independent sources and experiments followed and still follow the same scientific method founded in logic.

We can therefore say that the theory of evolution describes the fact of evolution, a phenomenon that can be observed and tested. We can see that species evolve, and the theory explains how species evolve.

What is a scientific fact?

When scientists draw conclusions, they are never set in concrete; that is, they are able to be modified through repeated tests and analyses. This is the central idea of scientific fact. As Stephen Jay Gould put it, “Science does not deal in certainty, so “fact” can only mean a proposition affirmed to such a high degree that it would be perverse to withhold one’s provisional assent.”

In other words, despite the fact (bad pun) that there are no true, 100% irreversible facts in science, we still hold things to be certain because they are so well-tested that it is ridiculous and illogical to say that they are untrue. The word “provisional” in Gould’s definition is important, because it implies that conclusions are only accepted temporarily; that is to say, they are accepted until our handy-dandy scientific-method evidence says otherwise.

In this way, science is a philosophy that is grounded in uncertainty. We all make mistakes, and so does science. But this does not mean that science always makes mistakes, and usually the mistakes that do happen are either only modified to become correct or the science that is being corrected was not really science. Perhaps the biggest mistake of “science” was believing that the sun revolved around the earth. Humans observed the rotation for thousands of years and drew the conclusion. It was not until the likes of Copernicus, Galileo, and other brilliant astronomers came along that the mistake was revised, via the scientific method. Once observable and quantifiable evidence was obtained to support the hypothesis that in fact the earth revolves around the sun, scientists changed their “provisional assent.”

Even though we once saw the revolution of the sun around the earth as a fact, we can’t really call it true science. It was not until about the 17th century that a more modern scientific model was developed. Even then, it was not the same one we see today. Therefore, many “scientific” claims before then, i.e. basically anything Aristotle said, was not the same kind of science we see today and has been debunked by modern theory.

So, just because something is observable does not mean it is a fact. To claim something is a fact, it must fit all aspects of the scientific method. Even then, it can be overturned, but only by something else that has passed the scientific method.

In Conclusion

  1. The theory of evolution describes the fact of evolution.
  2. The fact of evolution is a universal phenomenon that is supported by scientific evidence.
  3. Scientific evidence is obtained through repeated tests performed by independent sources using the scientific method.
  4. The scientific method is based on logic and rationalism.
  5. Logic and rationalism appeal to reason to justify their claims.

It is so highly unlikely that evolution will be debunked, since it is so well-supported and gets stronger every day, that scientists consider it a fact. Nevertheless, we should still question its validity for the sake of knowledge. The thing is, the more we question it and test it, the more evidence we find to support it.

What does change, though, is the theory of evolution. It is constantly modified, tweaked, and re-thought. You could say it evolves. Scientists are in perpetual disagreement as to how evolution happens, but nearly all of them agree that it does happen, because it is “perverse to withhold one’s provisional assent.” In other words, it’s just ridiculous to not believe evolution occurs.

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