Normative powers like promising allow agents to effect changes to their reasons, permissions and rights by the means of communicative actions whose function is to effect just those changes. An attractive view of the normativity of such powers combines a non-reductive account of their bindingness with a value-based grounding story of why we have them. This value-based view of normative powers however invites a charge of wishful thinking: Is it not bad reasoning to think that we have a given power (...) because it would be good? In this article, I offer a defence of the value-based view of normative powers against this surprisingly under-discussed objection. First, I clarify the challenge by distinguishing between two components of normative powers, which I call the material and normative components, respectively. Secondly, I defend the form of normative explanation involved, showing that it is needed to give convincing value-based explanations for other important normative phenomena, especially rights of autonomy. (shrink)