Comment by coderenegade

Who the consensus extends to is really the heart of the matter. Most people agree that killing certain people is wrong, but if they disagree on who those certain people are, there's no useful commonality. Some people believe that all killing of others is wrong, some believe that it's okay to kill others under certain circumstances (which can range from a threat to one's life, to petty "dishonor"), and some people historically believed that killing was a necessary duty (e.g. human sacrifice). There is no useful commonality to be had there. You can't appeal to the humanity of someone who doesn't see you as being the same as them, and the restrictions for inclusion as one of them can be arbitrary, broad, and fickle.

By definition, variation is the opposite of consensus.