Okay, I allowed a little more time to elapse between posts than I intended... Nearly three years, to be more precise, and - of course - a lot has happened in that time.
I'm calling today my 6 and a half year circumcision debate anniversary. I'm not sure if that's exactly right, and it could be a month or two either way, but I haven't kept records, and I think it's close enough. In mid 2003, I entered the public circumcision debate, and I've been involved on a daily basis ever since. I don't know how much impact I've had by myself (how can anyone identify the impact of a single person), but I figure it's more than zero. I hope so, anyway.
Anyway, at the moment I'm involved in three ongoing debates, and as a result of the events in these debates, I've been thinking about behaviour: how participants in a debate behave, and how that influences the debate. I'd like to try to codify some of the (informal) rules that I follow.
First, remember your audience. It's probably impossible to convince your opponent of anything, but other, perhaps more reasonable people are reading and they will be convinced by reasoned argument. If you're lucky, you'll hear from them privately, from time to time. So don't give up.
Second, be polite. This is the single most important rule, as few people pay attention to someone who is rude or abrasive, even if the rudeness isn't directed at them personally. An important part of this is avoid personal attacks, which includes subtle ones such as speculating about people's motives or thought processes. Remember: if someone seems like a crank to you, they probably seem like a crank to your audience, too.
Third, stick to the subject. If you're wrong, don't be tempted to change the subject. And if your opponent does, try pointing that out and stick to the subject yourself rather than joining him/her on the off-topic debate.
Fourth, if you mess up, admit it and apologise. Everyone's human, and everyone makes mistakes. It's much less annoying if you admit it.
Fifth, always provide evidence (or at least avoid making a point unless you know you can back it up with evidence).
Sixth, don't cherry-pick evidence. Present it all, both the bits that support your argument and the parts that do not. The key is to show that the weight of evidence supports your position, even if there are exceptions. And there probably are exceptions, because...
Seventh, remember that most evidence is imperfect. And some forms of evidence are better than others (see evidence-based medicine). The consequence of this is that you should expect a certain proportion of studies to be wrong, especially those of lower quality. In general, expect most studies to point in the right direction, but don't be surprised by a few that do not.
Eighth, not every battle is worth fighting. Don't spread yourself too thinly. Know when to walk away.