Real physicalism, then, must accept that experiential phenomena are physical phenomena. But how can experiential phenomena be physical phenomena? Many take this claim to be profoundly problematic (this is the ‘mind-body problem’). This is usually because they think they know a lot about the nature of the physical. They take the idea that the experiential is physical to be profoundly problematic given what we know about the nature of the physical. But they have already made a large and fatal mistake. This is because we have no good reason to think that we know anything about the physical