How do you feel on a scale of 1-10? Why this philosopher thinks she has a better way to quantify pain

The idea is that the colloquial descriptions people use to describe pain sensations could be linked reliably to the words and concepts doctors use to describe pain, like somatic or neuropathic, acute or chronic

Joseph Brean 5 minute read May 20, 2022

Philosopher Rachel Katz is developing an ontology of pain to bridge patient descriptions with medical concepts. Deb Ransom / Ottawa Sun

In the long-running annual series Oh, The Humanities! the National Post surveys academic scholarship at the Congress of the Humanities and Social Sciences, which is entirely virtual this year, from May 12-20.

Ingenious Pain, a popular 1997 novel about an 18th century English man who did not feel pain, begins with an autopsy in a barn.

As two doctors cut open the body of this peculiar man, who as a boy was an audience plant for a snake oil salesman to prove the powers of an elixir by submitting to deliberate burning and impalement, they eagerly anticipate a scientific breakthrough on the nature of pain. They even brainstorm the title of their learned report: “Some Thoughts, hm, upon the Case of the late Jm Dyer. An Enquiry into… the Curious and Remarkable… who until his twenty-something year was insensible to… knew not… entirely without all sensation… feeling… knowledge of… pain. With proofs, illustrations, exhibits and so forth.”

This would not have been the first such Enquiry. Pain has flummoxed philosophers, novelists, scientists and doctors alike since any of those professions existed. Wonderment at pain is as old as pain, or at least as old as wonderment. So the doctors did not find the secret truth about pain in Dyer’s entrails or beneath his scalp. They tried to pin down pain in the real world, and failed as usual.

Rachel Katz, a philosopher of ethics at the University of Toronto, is making a related effort to find the philosophical foundations of pain. She thinks the standard 10-point scale of how doctors ask patients to quantify pain is inadequate to the task and “frustrating,” and so are all the pain management apps that track it.

So she envisions a better one, an app that could automate the diagnosis of pain. It would map the colloquial expressions for pain onto the clinical concepts of medicine, making each patient’s reporting more useful, and offering aggregate data for studying pain across populations.

“By doing that, you potentially get a much clearer idea of what a patient’s experience is,” she told the Canadian Society for the History and Philosophy of Science. “Physicians still can’t read a patient’s mind. That’s still an issue.”

There are many words for pain, from mild discomfort to excruciating agony. Pain has qualities. It can ache or throb or sting. It has location, but also spatial dimensions. It can radiate, or focus. It has magnitude. It has both effect and affect. You can sometimes tell when someone is in pain just by how they look, or act. Pain sometimes goes along with other symptoms, such as nausea.

The idea is that the colloquial descriptions people use to describe those sensations could be linked reliably to the words and concepts doctors use to describe pain, like somatic or neuropathic, acute or chronic.

To do this, her goal is to develop what philosophers call an ontology, which is Greek for “theory of being.” Like a universal definition, this formal conceptual framework would bridge the patient’s vocabulary to the doctor’s by connecting both to the fundamental reality of pain.

This is not as abstract as it sounds. A similar ontology exists for genes and has been used to guide data collection in the study of model organisms.

Pain is trickier, though, because it involves subjective experience. But if you could do it for pain, you might be able to do it for other sensations like fatigue, anxiety or depression, all of which are presently tracked with clinical ten-point scales that are just as limited and coarse.

The International Association for the Study of Pain has a widely accepted definition of pain as “an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage.”

The trouble, philosophically, is there are three possibilities captured here: tissue damage, potential tissue damage, and something that feels like tissue damage but is not. The breadth of this definition is also its weakness.

Intuitively, people tend to think of pain as the body’s fire alarm, as if there were a finely tuned evolutionary system for producing pain as an alert in response to some precise harmful stimulus. But this turns out to be simplistic. People feel pain with no understandable cause. They feel pain in limbs they no longer have. The placebo effect, still mysterious, is largely an effect on pain. Pain is susceptible to shifts in attention, to distraction, to counter-stimulation. Scratching, for example, sometimes eases minor skin pain by applying more pain that, somehow, covers it up.

The privacy of subjective experience is not necessarily an insurmountable problem. Colour vision is also a private subjective experience, but the physiology and physics of it can be described so well that the classic late night half-baked dorm room philosophy question — what if my experience of “red” is different than yours? — can be objectively answered, more or less. It is not.

You cannot do that with pain, not as easily anyway. For one thing, colour vision is emotionally neutral. Pain is almost always unpleasant. So the ways people experience, respond to and describe pain can be culturally different.

Katz sketched the various pitfalls of creating an app to resolve that variation, and the possible limitations across languages and in pre-verbal children. From her audience, there was concern that she was not proposing an actual ontology, but more like a taxonomy, a way to classify pains without technically saying what they are. She disagreed.

“I argue that the use of an ontology to partially automate a patient’s diagnosis could reduce instances of misdiagnosis and protect patients from racism and misogyny within the biomedical system,” Katz wrote.

“I see this very much as the beginning of something,” she said.

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