I'm puzzled whenever people say things such as, "I have a high tolerance for pain." How would you ever know whether your "tolerance" for pain were actually a form of insensitivity? In other words, what's the (externally observable) difference between being able to tolerate or endure pain and simply not *feeling* pain? Maybe that guy who seems admirably tough and strong-willed actually just lacks the capacity for really powerful sensations. We talk almost as though there are two parts of a person: one part which feels the pain, and another which resists.

Compare the case of pain to the heat of spicy curries or steamy saunas: I recognize certain green curries to be just as hot/spicy as certain red curries, but I have a higher tolerance for the heat/spicyness of green curries; and I can tolerate steamy saunas better than in dry saunas even when I experience them as equally hot. I am not less sensitive to the heat of green curries or the heat of a steamy sauna, but I am not bothered by them as much as I am bothered by the heat of spicy curries or dry saunas. Why isn't pain like this -- tolerated differently in different forms, or by different people, even when the amount or degree of pain is recognized to be the same?

You might think that pain just is intolerance, and that the degree of one's pain is equivalent to the degree of one's intolerance, so that finding a sauna less intolerable should be equated with finding it less painful. But since the two words, "pain" and "intolerance" are used in rather different ways, and since (as you note) people do often say they are more or less tolerant of pain, it would not a linguistic equivalence. Still, as you suggest, if the evidence for one is equally evidence of the other then perhaps they are in fact the very same thing.

I do not think the evidence for one is the same as the evidence for the other, however. Aside from introspective reports (which constitute one kind of evidence, after all), here are some (more objective) kinds of evidence that help to distinguish insensitivity to pain from tolerance of pain:

(1) A racing heartbeat and tensed muscles (showing sensitivity to pain) together with a calm demeanor (showing tolerance of pain).

(2) A spontaneous cry or flinch (showing sensitivity to pain) together with willingness to continue painful procedure or activity (showing tolerance of pain).

(3) An ability to give nuanced reports on the character of one's pain (showing sensitivity to pain) together with lack of interest in using pain medications (showing tolerance of pain).

While (1) and (2) may suggest two parts oneself -- one responding automatically and the other more reflectively resists these automatic responses, (3) suggests an interesting, if unusual, disconnect between the feeling of pain and the awfulness of pain. You may be interested to look at a recent book by Nikola Grahek, entitled Feeling Pain and Being in Pain, that describe some carefully documented cases of pain without painfulness and painfulness without pain.

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