Too many liberals cannot see the incoherence of maintaining that we must respect other cultures because judgments as to right and wrong are culturally relative. They fail to see that if such judgments are indeed relative, then there cannot be any objective moral requirement that members of a given culture respect other cultures.
If all such moral judgments are culturally relative, then the members of a culture who believe that the strong have the right to enslave the weak are perfectly justified in enslaving the weak. For if right and wrong are culturally relative, then they have all the justification they could possibly have for enslaving them.
Valliecella, B. (2015) Facts, Opinions, and Common Core. Maverick Philosopher. Available http://maverickphilosopher.typepad.com/maverick_philosopher/2015/04/facts-opinions-and-common-core-1.html. Last accessed 8th Aug 2015.