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Why medical policymakers should beware Aristotle

September 21, 2010
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This coming Sunday (26th September) is ITV's Walk4Life Day, a series of organised walks in England and Wales designed to get people off their sofas and out on their feet. The event is linked to the department of health's Change4Life initiative, aimed at improving public health by promoting lifestyle changes.

Few would dispute the benefits of a good walk for both body and soul, but with so much of government thinking about health now focused on improving health rather than curing disease, what exactly is health? This was the topic of a recent interdisciplinary workshop, organised by King's College London's centre for humanities and health, which brought together doctors, philosophers and others experts.

One simple definition of health is just the absence of disease. But this definition demands a further definition: what, precisely, is disease? And this question, it turns out, is surprisingly difficult to answer. The word "disease" conjures up images of measles, cancer, schizophrenia—but what, if anything, do all these have in common?

To some philosophers, if the concept of disease is to be scientifically respectable it must be capable of explanation in value-free terms. Such philosophers, then, might wish to say that being ill is just being statistically abnormal. Thus people with hypertension count as ill because their blood pressure is much higher than the norm.  But it's not that simple. As Elselijn Kingma, fellow at the KCL centre, pointed out, blood pressure is typically raised during pregnancy, so a pregnant woman may have abnormally high blood pressure compared to the population as a whole, whilst enjoying a perfectly healthy pregnancy—that is, she's not ill. Of course if we compare her not to the population as a whole but to the sub-population of pregnant women, she's normal, so the health-as-statistical-normality theory gets the right answer. And what decides which population or sub-population we ought to consider? Perhaps value judgments need to be made here—so fixing the norms by which health and disease are to be measured is not as value neutral as some scientifically-minded philosophers would like to think.

If statistical abnormality won't do the trick, can we define disease in terms of impairment of function? Here again, a host of questions crowd in. What, as human beings, is our function? A response like "survival and reproduction" has the ring of hard science to it, but since many diseases affect us for the first time when we are past reproductive age, that notion of function doesn't get us very far.

Inspired perhaps by the rather different notion of man's "function" to be found in Aristotle, some at the workshop—including MM McCabe, professor of ancient philosophy at KCL, and Richard Smith, former editor of the BMJ—turned their backs on the idea that health is the absence of disease, in favour of a broader notion of health that brings it close to wellbeing, or leading a good life. This is certainly Aristotelian: the best life for human beings, according to Aristotle, is the life in which we perform our "function" well. It also seems to chime with the thinking behind the Change4Life initiative.

But consider someone who calmly faces imminent death from cancer, refusing to allow it to cloud their appreciation of the goods in their life, past and present. They have surely developed the art of living to perfection. But just as surely, they are ill, and if we blur the line between a strict notion of health and a broader notion of living well, then this obvious truth (the cancer patient is ill) becomes hard to articulate. The director of the Wolfson Institute of Preventive Medicine, Sir Nicholas Wald, argued that—though we need more than just statistics to understand why—being healthy may well turn out to be simply not being ill.

So does it matter whether we or the government think of health narrowly, as the absence of disease, or broadly, as more like wellbeing? After all, a nice walk will do you just as much good whatever your concept of health. But it may matter nonetheless. For a start, wellbeing is harder to achieve than absence of disease, but if the broad conception of health is adopted, there's the risk of government wasting money in pursuit of a remote target at the expense of the real and nearer one. What is more, if wellbeing is redescribed as "health," the business of formulating policy for achieving it—if there can even be such a thing—falls naturally to doctors and public health officials. But it's far from clear that something so complex and stubbornly un-medical should be left solely in their hands.

Edward Harcourt is a lecturer in philosophy at Oxford University

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