 When it comes to our knowledge of other minds, the disjunctive move allows us to hold that, where behavior is genuinely expressive of another’s mental life, there our experience of her behavior will yield (sceptic-proof) knowledge of another’s mental life. Genuinely expressive behavior is being thought of not as evidence (a symptom) of another’s mental life but as a criterion of it. This, McDowellian, understanding of criteria—in contrast to Wright’s  (§1.3)—requires  that we accept behavior in at least some cases to be expressive of, a criterion of, mental states. So understood, behavioral criteria are indefeasible. This is not to say that error is not possible, as the person I encounter may be deceiving me. However, in such cases the criterion for the mental state is not satisfied. The important thing is that this possibility should not be taken to negate the fact that, when the other person is not deceiving me, my experience of her behavior can result in (sceptic-proof) knowledge that she is, for example, in pain. The genuine possibility that others may deceive me should not be taken to open up the possibility that all others may be zombies and that I am in the world  alone.[5]  (We may here consider something Wittgenstein writes (1992, 94e): “But of course it isn’t true that we are never certain about the mental processes in someone else. In countless cases we are.”)