When I was a grad student, I had romantic notions about how knowledge was gained, how science was done and how democracy worked. Little by little, those notions have changed.

One blow came when I was doing field work at a 19-million-year-old fossil site in Africa. This wonderful site had six different species of fossil hominoids all living in the same place at the same time. It had been declared a national monument, and yet the shoestring budget couldn’t muster the funds to bring all the fossils back to the museum. Many had to be left to erode into dust, along with all the knowledge they could have offered.

I had the notion that scientific investigation was always well planned-out, with reasonably clear and specific expectations for how knowledge would advance. This view was challenged when my adviser at Yale explained how a crucial discovery in human evolution actually came about. They were in the field in Africa, he said, and they were really bored. No one had found much of anything and it was too hot to breathe anyway. The only thing they kept finding were piles and piles of fresh elephant dung. It’s not clear how it got started, but at some point somebody chucked a handful of elephant dung at someone, and pretty soon they were in the middle of an elephant dung slinging contest. At one point, he hit the deck to avoid getting plastered, and right in front of his eyes was a fossilized footprint. The dung-slinging escapade led to the discovery of a trail of 3 million-year-old footprints made by three individuals of the same species as the fossil hominid Lucy. Three million years ago, a volcano had erupted, and before the ashfall had hardened, these three had crossed the tuff. Two of the individuals were walking together, and the third, a tiny child, was stepping into the footprints of one of the adults. This wonderful find was the result of serendipitous elephant dung.

That’s not exactly how I thought science worked. But it turns out that gaining knowledge and doing science is a messy business, impinged on by all sorts of prosaic issues like funding and elephant dung. And I’ve come to love seeing how embedded science is in the rest of human endeavor. I’ve learned to value such stories as going to the heart of science as a very creative and very human enterprise.

But what about democracy? What about the noble Constitution? I used to think the US Constitution was fixed, an absolute guarantee of freedom of speech, freedom of religion, freedom of the press in this country. The past five years have shown me that the Constitution is valuable only insofar as people are willing to stand up for the rights it protects. Our freedoms are guaranteed only as long as ordinary, everyday people are willing to claim them–indeed, to insist on them.

People ask me, Why pour so much energy into protecting science education? Why not fight for literacy generally or any of a thousand other educational issues? I have two answers. One is easy: I know about evolution, so it makes sense that I would work on what I know best. The second is harder to grasp. And that is that freedom of religion is the bedrock foundation of liberty in this country. If we allow certain special-interest religious groups to co-opt the public school science classroom, to use it as a vehicle for converting children to religious views their parents don’t hold, if we allow them to spout outright lies about the nature and content of science, what do we really have left? If you can lie about science and get away with it, you can lie about anything.

Evolution is just the tip of the iceberg or, as the creationists put it, the leading edge of “the wedge.” The wedge they are seeking to drive through the heart of American democracy. The lies about science are not limited to evolution. Every day more lies about science seep into public consciousness. Lies about stem cell biology, lies about global warming, about clean air and water, lies about sexuality, about conception and contraception, lies about the effects of hurricanes on metropolitan infrastructure.

The war on science is a war on democracy itself. And the special weapons and tactics are rhetorical. The enemies of democracy use the language of tolerance to attack it from inside. Why, they ask, are we “censoring” the evidence for “intelligent design”? Why do we deny our teachers the “right” to use their “academic freedom” to teach “critical analysis” of evolution. Isn’t it only fair to teach both the evidence for and against evolution? All these clever ploys play well in the media on this issue and many, many others, and we will see these word games more and more in coming years. I call it the “orange is the new pink” strategy; every time the public cottons on to a catch term like “creation science” or “intelligent design,” they change to a more neutral-sounding term like “critical analysis” or “evidence against.” But defenders of American freedom are learning to stand up and say no, it really is fair to forbid teachers to lie to students, to prohibit school boards from using the power of the state to convert children to other peoples’ religions. Tolerance requires judgment.

So the rhetorical battle is pitched and the enemy is well armed. But it turns out that standing up for freedom and democracy is a lot like doing science. You start with noble principles and do the best you can, but when you get right down to it, you spend a lot of time dodging elephant dung.

Defending the Constitution is a messy business, but is it worth it? You betcha. Our future depends on it.