  Discrimination is prohibited by six of the core international human rights documents. The vast majority of the world’s states have constitutional or statutory provisions outlawing discrimination (Osin and Porat 2005). And most philosophical, political, and legal discussions of discrimination proceed on the premise that discrimination is morally wrong and, in a wide range of cases, ought to be legally prohibited. However, co-existing with this impressive global consensus are many contested questions, suggesting that there is less agreement about discrimination than initially meets the eye. What is discrimination? Is it a conceptual truth that discrimination is wrong, or is it a substantive moral judgment? What is the relation of discrimination to oppression and exploitation? What are the categories on which acts of discrimination can be based, aside from such paradigmatic classifications as race, religion, and sex? These are some of the contested issues.