Moral language persuades best when opinions are not yet formed, which is why writers of children’s literature can get away with saying things like, “Mr. Billings was an awful, horrible man with a heart of stone.” This sounds like a line from a children’s book because it employs persuasive methods that, though appropriate for children, would insult the intelligence of most adult readers.

Most moral discourse is the conversational equivalent of children’s literature. Disputants speak to one another—or, rather, at one another—as if their interlocutors failed to pay adequate attention on the day elementary morality was explained. Unaware of the projective nature of value, they marvel at their opponents’ blindness, their utter failure to see what is so perfectly obvious. Not knowing what else to do, they scold their opponents as if they were children, and scold them as if they were belligerent children when they fail to respond the first time.

What to do about this? Take a cue from good writers. Stick to the facts. Keep evaluative language to a minimum, and get rid of the most overtly judgmental, moralistic language.

-- Joshua Greene, The Terrible, Horrible, No Good, Very Bad Truth About Morality And What To Do About It