The multicultural relativism argument took a giant hit in the late nineties when the practice of female genital mutilation/circumcision began to be publicized. I remember innocently observing to a super liberal law professor that arguments for relativism began to look like pretty pale beer against such suffering. He clinched up a bit and ended the conversation rather quickly. This highlights left-wing dilemmas that someone should be documenting somewhere. I can think of a few.
1. Should you side with the non-western, third world practitioners of female circumcision or the feminists who condemn them?
2. Would you have supported the expansive reading of the Interstate Commerce Clause of the Constitution adopted by FDR if the president had instead been a Ronald Reagan type itching to reform the economy through free-market measures?
3. Would you back the radically pro-choice president or the victims of his sexually harassing behavior?
There are more, I am sure. If you have ideas, email me here.