I'm glad you said this. It is a part of what I was going to say to @uumlau. I think this will hold true pretty much regardless of what you believe is moral. The first part is, like I said, practically a tautology. The second point is that self-righteousness basically impairs, as erm was saying, meta-cognitive abilities. I think when people get the idea they are in the right, it's kind of like a mandate to do what they are doing. What they are doing is good, what poses an obstacle to what they are doing is bad. One thing that would be an obstacle, is a person trying to inform you that you are mistaken. So that person's commentary will be rejected. And I think it suffices to say that no matter what you think is good, your ability be good (or good at any thing for that matter) is impaired by a refusal to process input. No matter what you think is good, if you already think you're doing it, and process no further information on what you are doing, it's going to limit your capacity to do it.