February 11, 2008

Is biological evolution "just a theory"?

In the creationist rhetoric we often see the claim that evolution is "just a theory." When creationists say this they are using the colloquial meaning of the word "theory" in order to pretend that evolution is just a guess, a speculation, a conjecture. While a guess or conjecture is one dictionary definition of the word "theory," when we're talking about science and how the word "theory" is being used by scientists in reference to evolution (the theory of evolution), then what we need to know is how the word "theory" is used in the context of science.

The first two definitions of "theory" as given in the American Heritage Dictionary are what are relevant to the context of science:

1. A set of statements or principles devised to explain a group of facts or phenomena, especially one that has been repeatedly tested or is widely accepted and can be used to make predictions about natural phenomena.

2. The branch of a science or art consisting of its explanatory statements, accepted principles, and methods of analysis, as opposed to practice: a fine musician who had never studied theory.

For example, we also have the theory of gravity. Gravity is not just a guess, not just a speculation, and neither is evolution. So when creationists pretend that evolution is "just a theory" in the sense of being merely some kind of guess or speculation they are not using it in the dictionary sense of the word as the word is used in science when scientists refer to the theory of evolution. The dictionary sense of the word tells us that evolution is a set of scientific principles "that has been repeatedly tested" and that "can be used to make predictions about natural phenomena."

Creationists often play games with words like this in their rhetoric to try to obfuscate the actual facts and confuse people about the proper understanding of the relevant concepts - in other words, creationists love to play all kinds of word games to misrepresent matters as much as possible - but we should be careful to clarify such words correctly as part of showing why the creationist rhetoric is wrong.

Evolution is indeed a scientific theory, not because it's merely some kind of speculation, but precisely because over the many decades since Darwin the theory has been so extensively tested and refined in a variety of ways and in a variety of areas of scientific research.