THE PHILOSOPHY OF PAIN: THE SENSE OF PAIN
Aware that they could no longer accept Cartesian thinking, which insisted that a sensation was no more than a mental representation of a stimulus, the International Association for the Study of Pain asked a group chaired by the psychiatrist Harold Merskey to provide a modern definition of pain. They said: 'Pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage.' They added some crucial notes: 'Pain is always subjective . . . This definition avoids tying pain to the stimulus.'
In the classical view, stimulus leads to pure sensation which leads to perception. Tissue damage leads to pure pain, which leads to pain and unpleasantness. But in the modern view, stimulus may or may not lead to perception. Tissue damage may or may not lead to pain, which is an unpleasant experience.
There were two reasons for the new definition. First, observation and introspection failed to find a correspondence between tissue damage and pain. Second, no ordinary person ever experienced a pure pain that was not accompanied by unpleasantness. It is an honest definition of what we observe in ourselves and others, and it avoids the step invented by neat-minded philosophers that there must be at first a pure sensation which is later followed by the mental value judgement, which assigned emotional value, such as unpleasantness, to the pure sensation.
You may well question the usefulness of using only the single word 'pain'. To bring order to our world, we humans are passionate classifiers. We love the act of sorting and assigning pigeon-holes. Now we have a definition of pain. Pains can be big or small but is it true that one toothache equals two headaches? Melzack, spent many years collecting words that people used to describe their pains. He found seventy commonly used words, which he sorted into categories. Some words, such as 'pricking' or 'hot', seemed to be used just to describe the stimulus itself. For each of the classes of sensory word, the words were arranged in order of intensity,- for example, 'hot', 'burning', 'scalding', 'searing'. Then there was another class of word, which he called affective, which described what the sensation was doing to the victim; for example, 'exhausting', 'sickening', 'punishing'. Finally, he separated out words which he called evaluative, which expressed the degree of suffering; for example, 'annoying', 'miserable', 'unbearable'.
Patients were presented with the full list of words arranged in boxes and they were asked to tick which words best described their pain. Try it yourself. You may disagree with the way he has arranged the words. Rearrange them. Add your own if you think words are missing. Very extensive testing of this method, which became known as the McGill pain questionnaire, showed patients falling into loose groups which were characteristic of their disease. We will return to their answers. One example has already been discussed for patients entering an emergency room where all patients were eventually in pain. They used words about their pain which did much more than describe its intensity. The word 'pain' for each person had at least three dimensions beyond its intensity. Melzack called the dimensions sensory, affective and evaluative. You might wish to describe your pain in other ways. The point here is that the single word 'pain' has several components that combine in the individual to express what they mean by their pain.
In this chapter, we have examined and criticized the proposition that the mind and body are separate entities. The individual is certainly capable of an elaborate analysis of events and of the generation of skilled responses, but these may occur with no cognitive awareness. Pure pain is never detected as an isolated sensation. Pain is always accompanied by emotion and meaning so that each pain is unique to the individual. The word 'pain' is used to group together a class of combined sensory-emotional events. The class contains many different types of pain, each of which is a personal, unique experience for the person who suffers.
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