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Tuesday, May 20, 2008

Theories, facts, laws and doubting the truth of natural selection

In my small way, I have argued for many years that part of the disagreements over origins are because terms haven't been well defined. I was thinking principally of the term, "evolution," which, to some, is mostly about, say, the emergence of antibiotic-resistant bacteria, while to others is about the origin of living things by exclusively random, purposeless processes.

I'm right about that. There is some muddy thinking about the meaning of evolution, some of it purposefully muddy, probably. Such muddiness has led to some unnecessary and avoidable disagreements on the topic of origins. However, I haven't gone far enough. There is also disagreement, or misunderstanding, about such important terms as fact, theory, law, and hypothesis, as they are used by scientists, and by the public at large. Again, such misunderstanding has led to some unnecessary and avoidable disagreement about origins, especially in statements such as "evolution is just a theory, so it doesn't need to be taken seriously." A recent article has attempted to clarify these matters.

The author, T. Ryan Gregory, writes that "Theories explain facts and are tested by generating hypotheses. No matter how much information accrues, hypotheses never become theories, and theories never graduate into laws. These terms describe three distinct aspects of science." ("Evolution as Fact, Theory and Path," Evo. Edu. Outreach (2008) 1:46–52, November 20, 2007. Quote is from p. 48.) He explains his reasoning carefully, and I believe that most all scientists, whatever their beliefs about origins, would agree with it. I also believe that non-scientists can read and understand his reasoning.

He also says:
That evolution is a theory in the proper scientific sense means that there is both a fact of evolution to be explained and a well-supported mechanistic framework to account for it. To claim that evolution is “just a theory” is to reveal both a profound ignorance of modern biological knowledge and a deep misunderstanding of the basic nature of science. (p. 50)

Gregory also points out that there is an opposite error sometimes made, namely that evidence of common descent is taken as evidence for natural selection, which, he says, does not necessarily follow.

Thanks for reading!

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