Disagreement about value or about the facts?
Both within and outside ethics, people often worry about disagreements that are purely about value. Suppose that you and I completely agree about all the empirical facts about some case, yet you think that it’s absolutely forbidden to do something and I think there is absolutely nothing wrong with it. It can seem hard to see how we could ever resolve our disagreement. If after I have carefully considered the case, and still see nothing wrong, what could you possibly say that would make me see things in a different light?
Things are often a bit more complicated than this. For example, even if we agree on all the empirical facts, our moral disagreement might be due to disagreement about some metaphysical matter—say, about whether a foetus is a person. Metaphysical disagreements are also extremely hard to resolve. Then there is the old point that the way we frame factual matters, or the way we interpret some empirical evidence, might itself be shaped by our values.
Anyway, this is a common worry. But when it comes to many heated disagreements about scientific or technological advances, this worry seems to me to get the situation exactly backwards.