This paper attempts a conceptualisation of authority intended to be useful across all areas where the concept is relevant. It begins by setting off authority against power, on the one hand, and respect, on the other, and then spells out S1’s authority as consisting in S2’s voluntary action performed in the belief that S1 would approve of it. While this definition should hold for authority generally, a distinction is made between three different kinds of authority according to what grounds them: (...) personal, acquired and bestowed authority. Authority thus defined is then used as an example to argue that there is a kind of property that is response-dependent , but, consisting in all and only a response, is ontologically different from both secondary qualities and value judgments. While secondary qualities are interactive in that they depend on both the object and the perceiver and on what they are like, genuinely R-D qualities depend ontologically and metaphysically only on the responder. And whil.. (shrink)