MORE THAN A ‘THEORY’….By way of John Cole, we see that James Q. Wilson helped highlight one of my biggest pet peeves in all of public policy discourse: when opponents of modern science dismiss evolutionary biology as “only a theory.”

People use “theory” when they mean a guess, a faith or an idea. A theory in this sense does not state a testable relationship between two or more things. It is a belief that may be true, but its truth cannot be tested by scientific inquiry. One such theory is that God exists and intervenes in human life in ways that affect the outcome of human life. God may well exist, and He may well help people overcome problems or even (if we believe certain athletes) determine the outcome of a game. But that theory cannot be tested. There is no way anyone has found that we can prove empirically that God exists or that His action has affected some human life. If such a test could be found, the scientist who executed it would overnight become a hero.

Evolution is a theory in the scientific sense. It has been tested repeatedly by examining the remains of now-extinct creatures to see how one species has emerged to replace another. Even today we can see some kinds of evolution at work, as when scholars watch how birds on the Galapagos Islands adapt their beak size from generation to generation to the food supplies they encounter.

The point of Wilson’s piece was to dismiss intelligent-design creationism, but thankfully, he also took time to deal with this confusion surrounding “theories.” Watch any conflict over evolution and, within minutes, you’ll hear a creationist insist that students should be exposed to competing “theories” and that the “theory of evolution” is no better than any other “theory.” The idea is to suggest that if the science were absolutely true, it’d be called the “fact of evolution.”

It’s maddening, and yet, the reality-based crowd has to keep dealing with it. The National Academy of Sciences, one of the world’s most respected institutions of scientific and engineering research, took this on a few years ago.

Scientists most often use the word “fact” to describe an observation. But scientists can also use fact to mean something that has been tested or observed so many times that there is no longer a compelling reason to keep testing or looking for examples. The occurrence of evolution in this sense is a fact. Scientists no longer question whether descent with modification occurred because the evidence supporting the idea is so strong.

Gravity is a theory; just like electromagnetism, plate tectonics, general relativity, and evolution. But that won’t stop a few misguided souls in Georgia (and elsewhere) from insisting that science textbooks feature warning labels that tell students that evolution “is a theory, not a fact.”

The mind reels.

Steve Benen

Follow Steve on Twitter @stevebenen. Steve Benen is a producer at MSNBC's The Rachel Maddow Show. He was the principal contributor to the Washington Monthly's Political Animal blog from August 2008 until January 2012.