The recent news about a former climate-change denier changing his tune — in a study funded by fossil-fuel interests, no less — got me thinking. Well, that and the seemingly endless series of Republican debates. In watching coverage of the debates, something kept nibbling at the back of my mind, something I couldn’t put my finger on. But I finally figured it out.

In talking about global warming and evolution (and in some cases, both at once!) the Republican candidates tend to fall back on some variant of this phrase:

“It’s just a theory.”

Evolution? Just a theory. Global warming? Just a theory.

Let me back up for a second and lay out some disclosure: I believe that — no, wait a minute; strike “believe.” Evolution is real. We know evolution is real because we see it in action. Ever hear of MRSA? Methicillin-resistant Staphylococcus aureus has become a serious problem in hospitals and nursing homes over the past few years. S. aureus is a bacteria that usually lives pretty harmlessly on the human skin. Occasionally, though, it can flare up into relatively serious infections. Historically, these infections have been pretty easily treated with penicillin or other antibiotics. Then came MRSA. This nasty little critter dodges most of what we would normally throw at it, forcing doctors to bring out the big guns. Where did it come from?

Evolution. Wide use of traditional antibiotics killed off, by definition, only those strains of staph susceptible to traditional antibiotics. What was left were the ones that had mutated in such a way that traditional antibiotics didn’t wipe them out. New drugs, hardier bugs. Survival of the fittest. Sound familiar?

(As an aside: I happen to agree with Newt Gingrich that recognizing the truth of evolution doesn’t mean you can’t also believe in a divine Creator. Unless you take the Bible as word-for-word accurate, and believe that the world was created in six twenty-four-hour days — in which case, I’d like to ask you some questions about Genesis 1:27 vis-a-vis Genesis 2:22, among others — there’s nothing in evolution that precludes the idea of a Creator guiding the mutations that result in evolution. In fact, I tend to find that idea more elegant.)

So, that’s evolution. Global warming? I’ll say I’m not nearly as up on the science here, but I’m willing to take the word of ninety-seven percent of the people whose job it is to know about this stuff. Because the alternative is a laughable global conspiracy with basically no upside for the alleged conspirators. (But you know what? Even if global warming is a complete fabrication, what the hell is wrong with working to reduce waste? That’s the fundamental goal of proponents of global warming, you know: to reduce waste. Fossil fuels are absurdly inefficient, and thus expensive far out of proportion to the benefits they provide. If we can come up with more efficient, less wasteful, less expensive ways of doing things, why wouldn’t we? I don’t know about you, but my parents taught me that waste was bad. But anyway.)

My point of these disclosures is that I recognize that having these views dismissed predisposes me to not take the dismisser seriously. But you know, it’s a big world, it’s a free country, you can feel free to believe what you want to believe, you know?

The problem is when you try to support your beliefs by saying these things are “just theories.” And that’s the point I want to make here. (I know, it took me long enough.) When you say that global warming or evolution is “just a theory,” you’re either displaying 1.) a dismaying level of ignorance about the way science works, or 2.) a cynical willingness to pretend to such ignorance if you think it makes you more electable.

Here’s why I say that: “Theory” in common parlance and “theory” in the context of science are two very different things. Anyone who took a single high school-level science class ought to know this. Outside of science, we use the word “theory” to indicate an untested idea. It’s the start of the process. If you say “I’ve got a theory: It could be bunnies,”  you’re essentially announcing your intention to explore the idea that bunnies could be at the root of your problems.

But in science, that’s called a hypothesis. A theory is what happens when a hypothesis has been rigorously explored. In other words, a hypothesis becomes a theory only after evidence has been gathered.

Now, this isn’t the end of the process by any means. Scientists are always re-evaluating theories to ensure they still hold up. That’s the great thing about science: You have all these really freakin’ smart people constantly checking to make sure everything works the way we think it does, so we don’t have to. And yes, sometimes new evidence arises that disproves a theory, even a long-held one. But that doesn’t change the fact that theories are based on evidence, not just wild speculation.

So dismissing a scientific theory — especially one as well-tested as evolution — as  ”just a theory” is simply absurd. It’s like saying Earth is “just a planet.” The Grand Canyon is “just a big hole.” America is “just a country.” (U-S-A! U-S-A!) What I’m saying is that it makes you look ignorant. And then we all laugh at you. Because we’re mean.

If you want to fall back on scientific skepticism, we call all discuss things rationally, like adults. Point out holes in theories and sic the scientists on each other. I have no problem with that. There are plenty of things that well-meaning adults disagree on, and there’s just so much we don’t know. But if you try to pretend that you know more than science does — but use words to do so that betray a fundamental misunderstanding about one of the basic precepts of science — well, it makes it hard for folks who know better to take you seriously. You might as well debate the existence of gravity.

You do believe in gravity, right?