Morality’s categorical imperatives point to its being non-relative.
People who start out with disparate moral views may see that in order to live together cooperatively they need to adopt a shared moral policy. Debate (on morality) is most likely to lead to convergence when convergence is itself seen to be a value to aim at. But when convergence is not of use–when there are two groups starting from disparate moral positions there will be no convergence. Reflection coupled with true belief leads to convergence over what the best course of action is, even when the parties in question are not interacting with each other.