In order to get a clearer view of what argumentative civility is and why it is important, we need to begin by saying something about why we argue. Argumentation is the process of articulating our reasons for holding our beliefs. The point of articulating our reasons is to put them on display so that they may be examined and evaluated. When we argue specifically in response to disagreement, we supply our reasons for the purpose of demonstrating to our interlocutor their strength, and the comparative weakness of the reasons that support opposing views. Argumentation hence has within it the idea that one should believe only what the strongest available reasons support; it is, again, the activity of supplying reasons for the purposes of testing and evaluating them. This means that arguers are committed to the possibility of finding that their reasons are weaker than they had initially thought or that their opponent’s case is in fact stronger than expected; and when one’s reasons come up short, one may have to revise one’s belief. Unless conducted against the background commitment to the possibility of revising one’s views, argumentation is pointless.
We now are able identify civility in argument with tendencies that enable the exchange of reasons among disputants. Chief among these concerns the need for those who disagree to actually engage with each other’s reasons. This requires arguers to earnestly attempt to correctly understand and accurately represent each other’s views. For similar reasons, arguers must also give a proper hearing to their opponents’ reasons, especially when the opponent is responding to criticism. In addition, when making the case for their own view, arguers must seek to present reasons that their opponents could at least in principle see the relevance of. We can summarize these ideas by saying that civility in argument has three dimensions: Representation, Reception, and Reciprocity.The essence of incivility, then, is failing to engage with someone's reasons. Of course, rudeness tends to drown out engagement with reasons, but rudeness isn't the heart of incivlity.
Talisse and Aiken have gone for "3 Rs" and so have I, in my comment policy. Mine are "be reasonable, be relevant, and be respectful." I think this covers more or less the same ground as their more technical-sounding requirements.
Most of the time I find commenters here as civil as I could want. Things tend to degenerate only when I venture into the land of atheism--that's when we get into endless comment threads that go nowhere. One of the reasons these threads tend to be uncivil--remember, civility is engagement with reasons--is because it seems the atheosphere (pardon the hideous term) is full of people who have stories to tell about what was once done to them in some previous setting. They see a post with some connection to their stories, and they think "now's my chance to unload." And then it gets even worse--they get angry if they're denied the chance to unload. So they start off with "core" incivility--they don't offer a relevant, reasonable response to the post; and then move on to just plain rudeness.
If you've been reading my blog, you probably know I have a specific example in mind. My "Backlash Against Feminism" post talked about abusiveness toward a specific group of women (and supporters of women)--the X's, shall we say. Someone came along and said--wait, I'm not an X, and I've been abused too! This is basically like reading a post about the abuse of wives and commenting, "But wait, I'm a husband, and I've been abused too!" The comment would only make sense if someone were alleging that only wives get abused. And why would anyone say that? Likewise, why would I say that the X's are the only people ever treated abusively? It's especially strange, because I've written previous posts about non-X's being treated badly. There was nothing in my post and there is nothing anywhere in this blog to suggest I have the view that X's are the only people who have been treated badly in the atheosphere.
The X's are being treated badly, and I think it's strange (very strange) not to be willing to say so, and say it emphatically, and protest it, and take the time to understand why it's happening and how it can be prevented. (I like Phil Plait's "take" on that subject, over at Skepchick.) I don't think every time the treatment of the X's comes up we should allow the subject to quickly be changed to other transgressions. Not only is that rapid change of subject an injustice to these women, but if I write a post about the X's, it just does not engage with my argument and my reasons to divert the subject to a Y. It is, in the truest sense of the word, uncivil.