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Chronic Pain
Can Pain Be Defined?
A philosophical puzzle has become a medical priority.
Posted July 18, 2021 Reviewed by Devon Frye
We are all familiar with pain. Some of us, unfortunately, are much more familiar with it than others. Yet a definition of pain has long proven elusive.
Why is pain so difficult to define? Perhaps because pain has two aspects, one physical and objective and the other wholly subjective.
Consider the physical aspect of pain. If I burn my hand, I will typically feel pain, and that pain will be felt in the hand I burned. Treating the burn will, typically, treat the pain. In this sense, pain is a local and physical condition—not so different from the burn itself.
Consider the subjective aspect of pain. While a doctor can see that she has treated my burn, she cannot see whether she has treated my pain. Whether I am in pain or not is something that I am uniquely positioned to deliver an opinion on. In this sense, pain feels like it is outside the ken of medicine. It feels like it resides, ultimately, in the subjective and incorrigible perspective of the individual.
Why the Definition of Pain Matters
Should we define pain as a physical and local phenomenon or as a subjective and personal one? This philosophical problem has, in recent decades, become a medical one as well.
The medical community has increasingly come to see pain as a treatable condition in its own right, and not simply a symptom of other, underlying, conditions. In its boldest form, this attitude is expressed in the claim that pain is the "fifth vital sign" (alongside temperature, pulse, respiration rate, and blood pressure). Institutionally, this movement has seen the emergence of pain medicine as a medical specialty in its own right, with its own fellowships, journals, and professional associations.
In 1979, the International Association for the Study of Pain (IASP) proposed the following definition of pain:
An unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage.
This definition artfully incorporates the physical aspect of pain ("actual or potential tissue damage") as well as its subjective aspect ("unpleasant sensory and emotional experience"), binding them together and sidestepping centuries of philosophical conflict with the cagey word "associated."
Last year, however, the IASP announced that this definition was inadequate. They replaced it with the following definition of pain:
An unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage.
What has changed, and why?
One notable change is the omission of the term "described." The IASP committee felt that the inclusion of this criterion wrongly privileged persons with the capability of verbal descriptions, at the expense of infants, non-verbal adults, and non-human animals.
Another notable change is that pain no longer needs to be associated with (or described in terms of) tissue damage. Instead, it need only resemble the kind of experience associated with tissue damage. Notably, fibromyalgia is a leading cause of chronic pain but does not appear to actually involve any tissue damage. The appeal to resemblance is crucial in accommodating a widespread diagnosis as a cause of chronic pain. It is also philosophically telling.
Here is a trade secret of philosophy. Philosophers are supposed to be in the business of giving definitions, but philosophers spend most of their time showing that definitions do not work. Justice is not giving what is owed. The good is not what we desire to desire. Knowledge is not justified true belief.
Some have advocated a kind of conditional surrender in the struggle for definitions. Maybe we can never, or hardly ever, give reductive definitions or analyses of the things that matter most to us. But we can do something near enough. We can define our terms by pointing (with gestures or with words) to certain paradigm cases, and then defining our terms with reference to those paradigms.
The new IASP definition should be understood as a definition of this kind. We define a paradigm case of pain: a certain kind of unpleasant experience associated with tissue damage. Pain is to be defined as that experience, or any experience that resembles that experience. Thus the experience produced by fibromyalgia counts as pain because it resembles the experience produced by a burn or a toothache.
But this definition raises questions as well. For one: how much resemblance is needed? After all, everything resembles everything else in some respect, so how much resemblance is needed for a sensation to count as pain, and how is that resemblance measured? And who says whether this sensation is one that resembles pain? If it is the individual subject who decides, how is there any objective constraint on the notion of pain at all?
This last question may have been one the philosopher Ludwig Wittgenstein's had in mind in his "private language argument." Thus he writes, in section 293 of the Philosophical Investigations:
If I say of myself that it is only from my own case that I know what the word "pain" means—must I not say the same of other people too? And how can I generalize the one case so irresponsibly?
Suppose everyone had a box with something in it: we call it a "beetle." No one can look into anyone else's box, and everyone says he knows what a beetle is only by looking at his beetle. Here it would be quite possible for everyone to have something different in his box... But suppose the word "beetle" had a use in these people's language? If so it would not be used as the name of a thing.
What would it mean for pain to not be a thing? And, to return to our question, what would be a definition of pain that captured the subjective perspective of the individual while still being objective enough to ground clinical practice? Now physicians, as well as philosophers, feel the need to provide adequate responses to such questions. Given their depth and difficulty, the company is welcome.
