In debating politics, it's simple: "Attack the idea, not the person." It's one thing to say that "that's the nuttiest idea I have ever heard;" quite another to say that "you're a nutcase (as was recently posted)," for thinking that idea. It is often easy to forget that there is a live person reading these posts on the other end of the monitor: but they are and it reflects poorly on the whole discussion, when even one person uses personal attacks.