I don't encourage debates with creationists; it's a waste of time, gives them far more respect than they deserve, and leaves you feeling slimy for sharing a podium with the guy. A couple of years ago, though, I tussled with a creationist in a public forum, and I think there is a way to 'win' such a confrontation and still have some self-respect. This wasn't a full-blown debate: it was a presentation by a local creationist, Roger Melquist, in which he announced that he would be open to fielding questions afterwards. I showed up as an audience member, and my goal was simply to introduce at least a few facts into the event. Low expectations are good in this sort of thing. You aren't going to win converts, at best you're going to raise a few doubts and maybe make a few people think.

These are some revised strategy notes I scribbled up after my encounter with Melquist in Spring, 2001.

• Pack the audience. Creationists, and Melquist was no exception, usually lecture to church groups; there's no way a lone evolutionist can be a good guy in such a situation. No matter what, you're going to come across as an isolated sniper. Don't stand for it—spread the word to your peers, too. Match their flyers in local churches with similar announcements at your local university. In this case, our local biology club got wind of this talk, and they passed the word on to a philosophy of science class. There were a number of people in the audience who were capable of asking intelligent questions of the speaker, so it was more than an echo chamber for the creationists.
  Also, after I'd raised my hand a few times and asked pointed questions, Melquist started avoiding me. It was satisfying to see him pass over me to let another fellow a few rows back ask a question...and he was one of our smart young philosophy students.
• Prepare ahead of time. I'd seen some of the points this fellow was going to raise in a flyer that he distributed before hand, and he was clearly a young-earth creationist of the Walt Brown/Kent Hovind school (a sitting duck, in other words). Trust me, these guys are so predictable...a quick browse through the web sites of creationists and various online debates allowed me to put together a list of things he was likely to say, and he hit every one of 'em. A Behe- or Johnson-style speaker is a much harder target, but even there, you can practically find word-for-word outlines and refutations of what they are going to say ahead of time.
  You don't have to feel like you've got to slam him on every mistake; there will be lots, so pick and choose.
• Don't get bogged down in detail. Nobody at these things wants to hear a long lecture on evolutionary biology. Make your point in a few sentences or two, and move on. Especially since you're a member of the audience, you don't have the privilege of meandering on for 5 minutes. What helps here is a little preparation, too.
  For instance, I knew he was going to raise the tired old canard that there are no transitional fossils—they always do. I prepared a few pictures on transparencies ahead of time, and when he made his predictable claim, I was able to raise my hand and say, "what about this?" and show him a picture of Ambulocetus. When he said there was nothing to connect that to modern whales, I could just hand him a picture of Basilosaurus. When he got flustered and said that these were all just peculiar and isolated creatures, I gave him a third picture with a dozen fossils in order. I couldn't give a lecture on whale evolution, but I could say just a few words and show a few pictures and make the point that he wasn't telling everyone the whole story.
• Try to make points that anyone in the audience can understand. Even creationists can understand some simple logic, and you don't have to sell them short. One of Melquist's 'proofs' of the age of the earth was a truly bizarre calculation -- he said that every once in a while in the news you hear that a "leap second" is being added to bring the atomic clock standards into alignment with reality. By his calculation (which was way off anyway), the length of the day would have only been one hour long a mere 13,000 years ago. All I said was, "I can do you one better. We add a leap day to the year every four years. Therefore the year is getting longer by one day every four years, and 1500 years ago the year would have been only one day long." And then I mentioned that adding a leap day or second doesn't mean that the year or day is getting longer by that much, it just means that there is a discrepancy between the standards and the actual length. Everyone saw the flaw in his logic, and even those who were sympathetic to him were somewhat dubious after that.

The general consensus afterwards was that the evolutionists 'won', at least as determined by comments from other people there and the write-ups in the local newspaper. Melquist wasn't ground down into the dirt, there was no scoring, nobody went home feeling like a disillusioned idiot, but we'd managed to raise enough questions in everyone's minds that they went away thinking that our evangelical creationist didn't quite have a solid grasp on what he was talking about, and that maybe there was more to this evolution stuff than their minister claimed. The local newspaper reporter's story basically said she'd never thought much about the issue before and had thought of herself as a creationist, but after seeing the presentation, hearing the questions, and seeing how the speaker responded, she was leaning towards giving evolution a lot more credit. I think that's all we should aim for when we're looking for a 'win'.