While ghost-writing for the Conservative Missionary and the Libertarian Missionary, I found myself reflecting on the principles of good debating. I realize that debating can just be a sophistical exercise. But it doesn't have to be. In fact, it has obvious truth-seeking advantages over the straightforward lecture format. For starters, debaters usually have a knowledgeable opponent to keep them honest. Even better, debate gives people a chance to put the other side "on the stand" - to publicly ask them the tough questions people normally evade, then say, "Yes or no, Mr. Such-and-such?"
In any case, here are my candidate principles of good debating. They're not primarily about winning, but about deserving to win. But I do think that they are crowd-pleasing as well as truth-seeking.
Principle #1: Strive to address people who don't already agree with you. Realistically, you'll at best change the minds of the undecided. But the best way to sway the undecided is to reach out to your most intransigent opponents.
Principle #2: Talk to your opponent like he's your best friend, even if he does the opposite. Not only are ad hominem arguments invalid, but they send the signal that you lack better arguments. You'll also think harder and more creatively about your position once you spurn invective.
Principle #3: Split your time between talking to your audience and talking to your opponent. The optimal balance might not be 50/50 exactly, but you should spend a goodly amount of time both appealing directly to your opponent, and pointing out his blind spots.
Principle #4: If you're uncomfortable publicly defending aspects of your position, reconsider your position. In extremely oppressive societies, keeping your thoughts to yourself is common sense. But in modernity's largely open societies, your discomfort says more about the quality of your beliefs than the unfairness of the world.