|Rising in Noah's Ark, Aurelio Luini, 1556.|
OK, that's just my first impulse. Honestly, I think there are times when it's worthwhile to argue with creationists. Not because you'll convince them of anything, mind you--you almost certainly won't. Most of them are entirely unpersuadable. In fact, changing anybody's mind about anything is extremely rare, so if your goal is to change minds, you're mostly going to be disappointed. (I've never fully learned this lesson.)
But there are still a couple of reasons having the argument could be worthwhile anyway. One is that most creationists can at least be shaken out of their smugness a little, and that's a good thing. It's possible to give them pause, and make them think--just for a second--that their claims might not be as solid as they think, and that established scientific theory might not be as shaky and fraudulent as they think. It's also common that they will say something that shows they don't understand what the theory of evolution actually says; e.g. "If we came from monkeys, why are there still monkeys?" Many creationists don't actually understand basic science. They've read just enough creationist literature to think they know how to refute it.
Which brings us to the second, and far more important reason, it can be worthwhile to have the argument: other people are usually watching, and they may still be sitting on the fence. The person you're arguing with probably won't change their mind, but some of the people overhearing it might.
But this is risky, because if you don't know your stuff, it may be the creationist who sounds more convincing. A creationist who's spent a lot of time learning how to deny science can easily win an argument over someone who doesn't know how to defend it. Let's face it--most people who believe in science don't know enough to defend it well, and even someone who knows a lot about science can be stumped temporarily by some of the claims creationists throw out. That's because it's much, much easier to cast doubt on a complex theory than it is to defend it. This is especially true if the person casting the doubt is willing to be dishonest (or just repeating dishonest or delusional claims, which is more common), or if the people listening don't know science very well. As Alberto Brandolini put it, "The amount of energy necessary to refute bullshit is an order of magnitude bigger than to produce it."
It gets worse. Even if you DO know the science well, creationists will always be able to ask questions you can't immediately answer. If they throw out a wild claim about some purported finding that contradicts evolution, it takes a lot of work to track it down and figure out what's wrong with it. Nobody, not even professional scientists, knows enough to instantly refute every claim someone might make. There are dozens of such claims that have been answered here, but there will always be more of them. It's always easier to knock a theory down than to prove it, even if the theory is true.
The point is, the person attacking a complex idea usually has an advantage over the person defending it.* So what can you do? My suggestion is that at a certain point, you have to stop playing defense and go on the offensive. I don't mean you should be offensive--that's usually counterproductive, and in fact, it's probably best to be extra polite, since people get offended over religion three times as fast as any other topic. I'm just saying we need to turn the tables. If creationists want to talk evidence, then great, let's talk evidence--including their evidence.
When you start doing that, most creationists get pretty quiet, and for good reason. True Biblical literalists believe some pretty wild things. They believe there was once a snake who talked. They believe Adam was made from dust, and Eve was made from one of his ribs. They believe that every animal on Earth--including kangaroos from Australia, raccoons from North America, and penguins from Antarctica--somehow made it to the Middle East, and then squeezed together, by the millions, onto a wooden boat (and what about plants, fungi, bacteria, protists, and viruses? Surely they were passengers too?) Creationists believe Noah lived over 900 years, that floodwaters once topped Everest, and that people speak different languages because they tried to build a tower into the sky and God didn't like it.
So let's ask them this about all those things. Let's ask them things like: What's your evidence that a snake really talked? How do you know that women were created from a rib? Is there some genetic signature of these things? Do snakes have some sort of vestigial speech organs you can see in a dissection? Do women show genetic signs of being physiologically based on bone tissue? And how did Noah make sure every strand of bacteria and virus got on the ark? How did those raccoons get across the Atlantic? What's the evidence that people once lived for hundreds of years? Or that all languages can be traced to the Middle East?
Whatever holes creationists think they can poke in science, the holes in their theories are much, much bigger. And besides, turnabout is fair play. If creationists want to ask us about our evidence...great! We've got it, and lots of it. Museums, journals, rocks and DNA are full of evidence that backs us up. All of nature backs us up. Now let's ask them about their evidence. Let's hear what they've got on that talking snake and the 900-year-old man. I'm all ears.
* That's why, if a creationist asks me for the evidence for evolution or the age of the earth, I'm going to give it to them, but I know they will find fault with it. I can't help that, and there aren't enough hours in the day to explain why their objections are wrong--especially since they won't believe it anyway. It's enough for me to know that the only people who deny things like the accuracy of radiometric dating, stratigraphic methods, the constancy of the speed of light, and the authenticity of most fossils are people with a strong religious motivation to do so. The standard view of all these things is good enough for the US Geologic Survey, NASA, the National Science Foundation, the Royal Society, and dozens of other scientific bodies listed here. It's also good enough for oil companies who just want to find oil and make money. If you read what petroleum geologists write, you'll see references to million-year time spans, geologic ages, and the ancient environments that today's rocks came from. You won't see anything about Noah's flood.