We have all felt pain, but if asked to explain what it is,
we might be hard pressed to come up with a single
comprehensive definition. The International Association for
the Study of Pain (ISAP), a medical organization dedicated
to pain research, in 1979 convened a task force with this
very purpose, according to whom “pain is an unpleasant
sensory and emotional experience associated with actual
or potential tissue damage or described in terms of such
damage.” This definition states that pain is first of all
unpleasant, meaning that humans try to avoid it under
normal circumstances. Pain is sensory, meaning that it
involves the body’s nerves perceiving stimulation, but it
also has an emotional component involving the brain,
because it is unpleasant. Pain is associated with actual or
potential tissue damage: when you break a bone or touch
a hot stove, it hurts, letting the brain know to modify the
body’s behavior in order to prevent further damage and
allow for healing. Alternatively, pain is a feeling described
in terms of tissue damage, as in the case of a “stabbing
pain” or a “pounding headache.”