Does It Make Any Sense to Ask Whether Some Action

Does it make any sense to ask whether some action is right or wrong apart from any relation to a comparison class? Is the predicate "is right" functionally different from "is tall," "is sour," or "is located between A and B"? Don't we ask if Sam is tall in relation to Betty, or as compared with most people? We wouldn't understand what was meant by "sour" unless we had tasted sweet, would we? "Is the post office located between Main Street and First Street?" is a relational question that cannot be answered unless we had Main Street and First Street for comparison. Moral relativism asserts that "is right" needs a comparison class, too. Do you agree? Argue both pro and con sides of the issue.