 Since he is widely misinterpreted on this point, it is important to see that Williams is only offering a necessary condition for the truth of sentences of the form “A has reason to φ”. He is not (officially) committed to the stronger claim, that the presence of some motive which is served or furthered by φing is sufficient for the possession of a reason to φ. Officially, then, Williams is not defining or fully analyzing the concept of a reason; rather, the necessary condition itself represents a threat. (We say "officially" because there are indications that Williams unofficially held a stronger view; see the final paragraphs in this piece for elaboration.)