Arizona Superintendent of Public Instruction Diane Douglas, the state’s top education official, is once again on the attack against teaching evolution in public schools. Douglas has learned that she can’t just delete it from the curriculum, especially in favor of so-called “intelligent design,” because federal courts have ruled that that’s a violation of the U.S. Constitution’s “establishment clause,” which establishes the clear separation between church and state. So she’s trying to do it through the back door, by replacing the word “evolution” with phrases that sound similar to the layman but are not.
For example, according to a recent Capitol Media Services report, instead of the requirement that students be able to evaluate how inherited traits in a population can lead to evolution, they would now have to evaluate how those traits would lead to “biological diversity,” which says nothing about how the population changes over time in response to changing conditions.
Similarly, a reference to “the mechanism of biological evolution,” in other words, how evolution happens, would be replaced with “change in genetic composition of a population over successive generations,” which says nothing about how or why such changes occur.
This is nothing new. Religious conservatives have been trying for a long time to drive these kinds of changes, with the ultimate goal of ending the teaching of evolution, on the grounds that evolution is “just a theory.” This phrase takes advantage of the average citizen’s lack of understanding that the word theory means something different to scientists than it does to the general public. Specifically, to the ordinary citizen, a theory is an idea, a guess, a supposition. It could be right, it could be wrong. To the scientist, however, this is a hypothesis, something to be tested.
A theory is something far different. Back in 2005, as part of a presentation in one of my Master’s Degree classes, I put together this list of things that a proposal must do in order to be accepted by the scientific community as a theory. It must:
- Acknowledge and account for its assumptions
- Be the most accurate and comprehensive explanation of the known facts about its subject
- Make non-obvious predictions
- Be testable, and have survived attempts to disprove it
- Be able to evolve (yes, I chose that word intentionally) to accommodate new facts—or be discarded if it can’t, and
- Not be accepted merely on the say-so of a single individual or small group.
There’s one other thing about real scientific theories: they draw on the knowledge generated by other theories. One example: paleontologists can date dinosaurs back to the Cretaceous Era because they use radiocarbon dating technologies to determine how much of a radioactive form of carbon remains in the fossilized bones. The carbon decays to another, non-radioactive form at a set rate, known as its half-life, so how much of the radioactive form there is allows the age of the fossil to be calculated. Radioactivity and half-life are concepts that come from atomic theory. So far, opponents of evolution have not attacked atomic theory and “just a theory,” for which I’m grateful.
Finally, one could ask why, if evolution is so good, it’s still a theory, not on the highest step of science’s hierarchy, a law? It’s because it has not been proven to be universal—true everywhere, all the time—the way, say, the law of gravitational attraction has been. Until we find life elsewhere in the universe, we won’t be able to test evolution for universality.
Unfortunately, too few scientists have spoken up to explain these basic requirements in public forums, and as a result, in the minds of too many people, evolution remains “just a theory,” and as such, stands on equal ground with any other such “theory” anyone else might propose, whether it’s based in fact or not.