Friday, March 04, 2005

Evolution: Theory or Fact?

Time to nitpick:

The creationist cry, "Evolution is only a theory!" The biologists retort, "Evolution is both a theory and a fact!"

We've heard this point countless times, but I'd like to clarify an issue of hierarchy that is often times neglected. Evolution is a fact. We know that life on earth has changed over time, and that is the essence of the fact of evolution. Evolution is not a theory! There are, however, multiple theories for how life evolved over time.

The accepted mechanisms for how evolution occurs include both deterministic (natural selection) and stochastic processes (random changes such as genetic drift or founder events). Mutation provides the raw material upon which these forces act, but it is a weak evolutionary force on its own. Different evolutionary theories propose how the evolutionary forces interact, but they all assume naturalistic forces are responsible for evolution. There is no one "theory of evolution."

Intelligent design is not a theory. It can be classified as an untested hypothesis, and unless someone starts publishing results, it will remain an untested hypothesis. All of the accepted evolutionary theory has been tested and shown to reasonably explain some aspect of evolution. Intelligent design falls underneath the net of evolution, as it attempts to explain how life on earth has changed over time. This distinguishes it from young earth creationism, which does not acknowledge evolution as a fact. The problem with intelligent design is not that it challenges evolution, but that it is a sub par hypothesis to explain how evolution occurs.


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