Necessarily co-extensive predicates and reduction

Streumer argues that all normative properties are descriptive properties. His first argument is based on the principle that necessarily coextensive predicates ascribe the same property (N), and the claim that there is a descriptive predicate that is necessarily coextensive with normative predicates. From this Streumer concludes that normative properties are identical with descriptive properties. I argue that, even if we accept (N), this conclusion does not follow. Normative properties could only be descriptive properties if there is some descriptive way in which all instances of normative properties are similar. But Streumer does not show that, and the prospects for doing so are, I believe, not good. His second argument rests on the premise that the nature of normative properties cannot depend on which first order normative theory is true. I argue that this premise is false, and that the argument for it does not sit comfortably with (N)