 Introspection is the capacity to inspect the present contents of one’s own mind. Through introspection, one knows what mental states one is currently in: whether one is thirsty, tired, excited, or depressed. Compared with perception, introspection appears to have a special status. It is easy to see how a perceptual seeming can go wrong: what looks like a cup of coffee on the table might be just be a clever hologram that’s visually indistinguishable from an actual cup of coffee. But can it introspectively seem to me that I have a headache when in fact I do not? It is not easy to see how it could be. Thus introspection is widely thought to enjoy a special kind of immunity to error. But what does this amount to?