Distinguish facts that are normative and facts that have normative importance in the sense that these facts give us reasons. Two examples would be the facts that
(J) your wine is poisoned; and that
(K) the fact stated by (J) gives you a reason not to drink your wine.
Of these facts, (J) is natural and (K) is normative. But it is (J), the natural fact, which has normative importance, in the sense of reason-giving force... Whenever some natural fact gives us a reason, there is also the normative fact that this natural fact gives us this reason.
It is easy to overlook such normative facts... if we say that natural facts of certain kinds are reasons to act in certain ways, we may be led to assume that, to defend the view that there are normative reasons, it is enough to claim that there are natural facts of these kinds. That is not so. We must also claim that these natural facts have the normative property of being reasons. And this claim, property, and fact might all be irreducibly normative.
In subsequent chapters, Parfit similarly notes the importance of distinguishing right-making features of an act (e.g. maximizing happiness, or whatever) from the property of being right.