I take it that values (moral value, aesthetic value, etc.) are only knowable by ostensive definition (viz. by direct experience with the types of properties that any particular value is understood to be a token of). Now if true, I think that it is a mistake to suppose that they are merely the residue of the subjective states that they purport to be an experience of (a mere 'projection', as Mackie seems to suppose). Is it not equally true that 'objectivity' might be also coextensive with a property being "there in the world" even though the scale by which we measure it is a human construct? In other words, although the world does not come 'pre-sliced' into evaluative schemes, does it not still objectively 'answer' to the evaluative predicates we apply to it?