The topic of evil brought us to the topic of pain. Herewith, some distinctions and theses for your examination. With regard to physical pain, at least, we ought to distinguish among:
a) The physical substratum of the pain. The cause of the pain. In the case of lower back pain, for example, a pinched nerve. But not just the salient cause, e.g. the pinched nerve, but the totality of causal conditions in the body that 'underpin' the experience of pain. All that makes up the physical substratum of a physical pain.
b) The pain-as-felt, the felt pain. This is the pain one experiences or lives through. Pain as Er-lebnis. The phenomenal pain to which the subject of pain alone has access. (Access to the physical substratum is public; access to the felt pain is private.) With respect to felt pain, esse est percipi, to be is to be perceived. So for a felt pain, appearance and reality coincide. Its being as a mental datum is exhausted by its appearing. This is not the case with the physical substratum of the pain.
The felt pain factors into two aspects:
c) The sensory quale of the felt pain, its raw feel to use an old expression of Herbert Feigl. This is the qualitative content, the Nagelian what-it-is-like of the felt pain. Each pain feels like something to the one who has it, though he would be hard pressed to put this feeling into words.
d) The painfulness of the felt pain. The felt pain has a quality, but this quality is not the same as its painfulness. Thus I factor the felt pain into the sensory quale (raw feel) and the painfulness of it. Suppose I am outside in the cold and I feel a stinging sensation in my bare hands. It seems that the painfulness of this sensation depends, at least in part, on my attitude toward it, my aversion. Or consider any olfactory sensation you take to be unpleasant, the smell of cooking broccoli, say. One can learn to overcome such aversions, which is not to say that one overcomes the sensation itself. Or perhaps you are in a public restroom. You focus on the stench and remind yourself that it is only a sensation and one that betokens nothing harmful to the body. As a result of this reflection, the unpleasantness diminishes while the sensation itself remains constant. A reasonable inference from phenomena such as these is that the sensory quale of a pain and its painfulness are distinct, and not just conceptually, but in reality. In some cases it is the attitude of aversion that makes a sensory quale into a pain sensation, but I don't claim that this is true for all cases.
T1. Felt pain is mental, a conscious phenomenon. This is true of both physical and psychological pain. Physical pain, toothache, headache, backache and the like are called 'physical' because of their physical substrata -- see (a) above -- even though in themselves they are mental. Felt pain cannot be identified with any physical process. Correlated, but not identified.
T2. Felt physical pain is a conscious state with no intentional object. Pains are non-intentional experiences. They are not of or about anything in the way that believing and desiring are
object-directed. But here I need an argument since some maintain that pains exhibit intentionality or object-directedness.
Suppose we compare a visual perceiving of my foot, and a feeling of pain 'in' my foot. The perceiving of my foot is an intentional experience: the act of perceiving 'takes an accusative,' is directed to an object. The perceiving presents the foot as having such and such properties. But what does the pain present? It doesn't present damage to the foot, although there presumably is damage to the foot, a torn Achilles tendon, perhaps. The torn tendon is the cause of the pain sensation, but it is not the intentional object of the pain sensation. The torn tendon is hidden from the pain experience in the way the foot is not hidden from the visual experience. So what is the intentional object of the pain sensation? I say there is none. There is a pain sensation and its cause, but no intentional object. The cause is not presented to me by the pain sensation.
The relation of intentional experience to intentional object is nothing like the relation of pain to its cause. If X is caused by Y, then both X and Y must exist. But if X is an awareness-of Y, if X is intentionally related to Y, then Y need not exist.
For more on non-intentional experiences, see the Intentionality category.