The war on climate science has evolved rapidly over the past decade, with talking points surging and subsiding in wave after wave: The planet is not warming. The planet might be warming, but the scientific uncertainty is too great to be sure. The planet was warming, but the warming stopped. The planet is warming, but not because of anything that humans are doing. The planet is warming, but that could be a good thing. The planet is warming and not in a particularly good way, but there’s not much we can do about it. The planet is warming and possibly in a very bad way, maybe even because of human activities, but fixing it would be much too expensive.

Just when it seemed that climate deniers might finally be coming to their senses, several leading voices began backpedaling. But instead of asserting that global warming isn’t occurring or isn’t human-caused, they came up with a sly new way to suggest that the scientific jury is still out: total ignorance. As in ignore-ance.

The recent rash of ignorance started with a few Republican politicians who proclaimed that their lack of scientific training makes it impossible for them to determine whether scientists are telling the truth about global warming. By last week, Republicans in Congress were even ignoring experts from their own party: the heads of the Environmental Protection Agency under four Republican administrations, who testified that global warming is real, humans are causing it, and action is needed. Republican congressmen responded by trying to block funding for EPA’s proposed carbon pollution standards. Of course they did. The only science that interests them is political science.

Weasel words. “I’m not a scientist,” said Florida Governor Rick Scott on May 27, when asked whether human activities are significantly affecting the weather. Asked whether he is now less doubtful about the human influence on climate than he was in 2011, Scott simply repeated himself: “Well, I’m not a scientist.”

On May 29, House Speaker John Boehner spouted a slight variation on the theme: “Listen, I’m not qualified to debate the science over climate change.”

“Neither he nor I are a climate scientist,” said Tennessee Republican Marsha Blackburn in a debate with television personality Bill Nye “The Science Guy” three months earlier. “He is an engineer and actor. I am a member of Congress.”

Koch Brothers spokeswoman Melissa Cohlmia was on message, too, in a recent email to The Wichita Eagle: “We are not experts on climate change,” she wrote.

The “I’m not a scientist” mantra dates back to at least 2010, when Florida Senator Marco Rubio—who recently said he’s ready to be president—questioned the human contribution to climate change. “I’m not a scientist,” he told The Miami Herald. “I’m not qualified to make that decision… there’s a significant scientific dispute about that.” In a 2012 interview with GQ magazine, Rubio gave a similar answer when asked how old the Earth is: “I’m not a scientist, man. I can tell you what recorded history says, I can tell you what the Bible says, but I think that’s a dispute among theologians, and I think it has nothing to do with the gross domestic product or economic growth of the United States.”

Gosh, who knew that Rubio is an economist, an historian, and a theologian? His resume reveals only that he is a scholar of politics and the law. Perhaps an advanced degree isn’t necessary, after all, to understand (or claim to understand) the most elementary findings in an academic field.

Ignorance is bliss.It’s easy to see what climate skeptics like about the not-a-scientist line, which the website DailyKos labeled as “climate change-mutism.” It allows them to beat a quiet retreat from earlier, scientifically dubious statements on climate change while dodging uncomfortable questions. And “I’m not qualified to debate” tacitly implies that there is a serious scientific debate about global warming.

Mutism also makes the skeptic sound humble and respectful toward science. “The beauty of the line,” writes Jonathan Chait in New York magazine, “is that it implicitly concedes that scientists possess real expertise, while simultaneously allowing you to ignore that expertise altogether.”

Although professing respect, “I’m not a scientist” is actually a way of marginalizing scientists and relegating climate dialogue to elite scientific gatherings rather than making it part of broader public policy discussions. As Pat Cunningham points out in his blog at The Oak Ridger, Republicans “should say, in effect: We’re just like you. That science stuff just confuses us. But, by God, we’re not going to let the smarty-pantses tell us how to live.”

When know-nothings know something. Unfortunately for Boehner and buddies, it doesn’t take a smarty-pants to see the complications that result from pleading ignorance about science. If non-scientists can’t understand science, what’s the point of inviting scientists to testify at congressional committee hearings on climate science? And how can congressmen understand their own handpicked witnesses well enough to form any opinions on climate policy?

Imagine if politicians applied not-a-scientist reasoning to other areas of expertise: “I’m not a doctor, so I can’t comment on the Affordable Care Act.” “I never served in the military, so I can’t take a position on nuclear weapons.” “I’m not an economist, so I’ll recuse myself from voting on the proposed federal budget.” “I’m not an engineer, so don’t expect me to have anything intelligent to say about whether my state needs any new roads or bridges.”

Even people who are scientists aren’t necessarily experts on climate. But that doesn’t prevent them or anyone else from reading and comprehending reports such as the Intergovernmental Panel on Climate Change’s latest assessment or the one the National Climate Assessment recently released by a team of more than 300 experts. The fact that most of us aren’t climate scientists is precisely why we rely on such people for credible information and authoritative analysis—and public policy makers should do the same.

Has climate denial become cheesy? Most Republicans aren’t making a point of being non-scientists, especially after President Obama skewered the phrase in a commencement speech on June 14, offering his own translation of “I’m not a scientist”: “I accept that man-made climate change is real, but if I admit it, I'll be run out of town by a radical fringe that thinks climate science is a liberal plot.” Had climate deniers been around at the dawn of the space program, Obama said, they would have told John F. Kennedy that the moon “was made of cheese.”

We can’t get a taste of the moon, yet most of us trust science enough to believe that it’s not cheddar. With climate change, we can see for ourselves: coastal flooding, melting glaciers, extreme weather. Most Americans are not as clueless about what’s causing these changes as some of their elected representatives claim to be. A Gallup poll in mid-March reported that nearly six in 10 Americans believe that pollution from human activities, rather than natural causes, is responsible for the rise in global temperatures over the past century. Even among Republicans, 41 percent agree. And most of them aren’t scientists.