  As discussed in section 3 below, inverted spectrum scenarios have a wide range of philosophical uses, and come in a correspondingly wide range of flavors. It is not always required, for example, that Invert and Nonvert are behaviorally alike. But suppose that a behaviorally undetectable scenario is needed, and moreover one that is genuinely possible. With the assumption that Invert is otherwise normal, we just saw that Locke’s behaviorally undetectable scenario is not possible. Without relaxing the simple assumption about Invert, can we find one that is?