Gary B. Rollman University of Western Ontario
Given the universal nature of pain, it is surprising how difficult its definition can be. A moment's reflection may, however, bring the difficulty to the fore. Can you define pain without invoking synonyms such as "hurt" or variants such as "painful?"
Further reflection may raise additional problems. Is pain a sensation, a perception, an emotion, or a thought? How should it be compared with the other sensory experiences described in this volume? Does it belong in a unique category or is it part of a continuum with pressure or heat or cold?
Individuals faced with the task of dealing with pain, whether as researchers or clinicians, need to consider these philosophical dilemmas, but they also need to get on with the task of quantifying pain, attempting to alleviate it, and addressing the efficacy of their treatments. Fascinating challenges confront them in each of these endeavors.
While there is no universally accepted definition of pain, there is, in fact, an "official" one, presented by the Subcommittee on Taxonomy of the International Association for the Study of Pain ( Merskey, 1986a). Their definition states that pain is "an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage."
Note, first, that the definition emphasizes two components of pain: the sensory and the emotional. While the two are often linked, evidence from laboratory and clinical studies suggests that they can be distinguished and, often, treated separately.
Note, also, that pain is not necessarily linked to tissue damage. In fact,