One problem I see with such discussion is the lack of distinction between 'there is a cause for pain in the hand' and 'the brain senses pain in the hand'. One

One problem I see with such discussion is the lack of distinction between 'there is a cause for pain in the hand' and 'the brain senses pain in the hand'. One can see this nicely if you simply think of pain as light, the pain sensors as light sensors and the brain as a microprocessor, connected to the sensors. Certainly, if light is there, then the sensors will sense light, and thus, the two statements are equal in this case. However, if the sensor only senses light, one strictly does not know if there is light or not, as the sensor might malfunction. If one realizes this distinction between the existance of a state and the recognition of a state, things grow much clearer and one does realize that whatever is going on, one must consider a malfunction of the brain and nerves.