I wish I weren’t so surprised when I stumble into a civilized conversation online, but I am. Obviously, it’s easy when you agree with someone but less easy when you disagree.
Discovering that you disagree with another smart person is a joy. It’s an opportunity to change their mind or your own. I suspect the lack of civility typically comes from a lack of openness to change. I simply can’t participate in conversations on Neowin, Engadget, Gizmodo, or similar sites, because people seem only to be focused on proving their own points and putting down others.
Real conversation requires a certain level of openness to opposing views – a willingness to change based on what can be learned from others.