  Consider the representational property of having an experience of something’s looking red. By P1, this property is extrinsic, and so there is a possible world \(w\) in which a subject \(x\) has this property and \(y\)—a perfect duplicate of  \(x\)—lacks it. Solely for illustration, we may take \(w\) to be a possible world in which Nonvert and his twin Invert are both looking at a tomato in a white bowl (but perhaps the twins are on different planets). Nonvert is having an experience of something’s looking red, and Invert is not; more specifically: (i) the tomato looks red, and nothing looks green, to Nonvert; (ii) the tomato looks green, and nothing looks red, to Invert. By P2, Nonvert’s experience has \(Q_{R}\) (and not \(Q_{G})\); conversely for Invert. So Nonvert and Invert are twins whose experiences do not share qualia; in other words, qualia are not intrinsic. By P3, contradiction. Hence: