Let me first explain, then, what I mean by moral and moral science. A moral or ethical proposition, is a statement about a rank order of preference among alternatives, which is intended to apply to more than one person. A preference which applies to one person only is a taste. Statements of this kind are often called "value judgments." If someone says, "I prefer A to B," this is a personal value judgment, or a taste. If he says, "A is better than B," there is an implication that he expects other people to prefer A to B also, as well as himself. A moral proposition then is a "common value".