Osteoporosis and risk of fracture: reference class problems are real

Elselijn Kingma argues that Christopher Boorse's biostatistical theory does not show how the reference classes it uses-namely, age groups of a sex of a species-are objective and naturalistic. Boorse has replied that this objection is of no concern, because there are no examples of clinicians' choosing to use reference classes other than the ones he suggests. Boorse argues that clinicians use the reference classes they do because these reflect the natural classes of organisms to which their patients belong. Drawing on a thorough exploration of how the disease osteoporosis is defined in adults, I argue that clinicians do indeed make choices about which reference classes to use in diagnosis. Clinicians use young adult reference classes to diagnose osteoporosis in elderly patients. They also use young female reference classes to diagnose osteoporosis in elderly males. Clinicians adjust their reference classes so that the diagnosis of osteoporosis reflects a person's risk of sustaining a fragility fracture. The ethical intuition that people with the same risk of fracture should receive the same diagnosis overwhelms the naturalistic intuition that reference classes should reflect natural classes of organisms of uniform functional design. Clinicians construct a variety of reference class types, including pathological reference classes and epidemiological population-specific reference classes, to serve this ethical intuition. I show how clinicians use several reference classes at once so that they can more accurately predict risk of fracture. Ultimately, the reference classes chosen and used in medical practice are quite different from those proposed in naturalistic philosophy of medicine.

Experimental philosophy of medicine and the concepts of health and disease

If one had to identify the biggest change within the philosophical tradition in the twenty-first century, it would certainly be the rapid rise of experimental philosophy to address differences in intuitions about concepts. It is, therefore, surprising that the philosophy of medicine has so far not drawn on the tools of experimental philosophy in the context of a particular conceptual debate that has overshadowed all others in the field: the long-standing dispute between so-called naturalists and normativists about the concepts of health and disease. In this paper, I defend and advocate the use of empirical methods to inform and advance this and other debates within the philosophy of medicine.

Biological normativity: a new hope for naturalism?

Since Boorse [Philos Sci 44(4):542-573, 1977] published his paper "Health as a theoretical concept" one of the most lively debates within philosophy of medicine has been on the question of whether health and disease are in some sense 'objective' and 'value-free' or 'subjective' and 'value-laden'. Due to the apparent 'failure' of pure naturalist, constructivist, or normativist accounts, much in the recent literature has appealed to more conciliatory approaches or so-called 'hybrid accounts' of health and disease. A recent paper by Matthewson and Griffiths [J Med Philos 42(4):447-466, 2017], however, may bear the seeds for the revival of purely naturalist approach to health and disease. In this paper, I defend their idea of Biological Normativity against recent criticism by Schwartz [J Med Philos Forum Bioethics Philos Med 42(4):485-502, 2017] and hope to help it flower into a revival of naturalist approaches in the philosophy of medicine.

Theoretical and clinical disease and the biostatistical theory

Although concepts of disease have received much scrutiny, the benefits of distinguishing between theoretical and clinical disease-and what is meant by those terms-may not be as readily apparent. One way of characterizing the distinction between theoretical and clinical conceptions of disease is by relying on Boorse's biostatistical theory (BST) for a conception of theoretical disease. Clinical disease could then be defined as theoretical disease that is diagnosed. Explicating this distinction provides a useful extension of the BST. The benefits of this approach are clearly and non-normatively demarcating disease from non-disease, while allowing for values and purpose to determine what criteria are used in clinical practice to represent a disease's underlying dysfunction. Through discussion of a variety of medical conditions, including polycystic ovary syndrome and type 2 diabetes mellitus, I explore how the relationship between BST-based theoretical and clinical disease could make sense of various features of clinical practice and medical theory. It could do this by lending focus to a nuanced understanding of the pathophysiological defects present in disease and the means by which they are assessed. This could contribute to making sense of revised nosologies and diagnostic criteria.

Is "chronic kidney disease" a disease?

Several philosophers of medicine have attempted to answer the question "what is disease?" In current clinical practice, an umbrella term "chronic kidney disease" (CKD) encompasses a wide range of kidney health states from commonly prevalent subclinical, asymptomatic disease to rare end-stage renal disease requiring transplant or dialysis to support life. Differences in severity are currently expressed using a "stage" system, whereby stage 1 is the least severe, and stage 5 the most. Early stage CKD in older patients is normal, of little concern, and does not require treatment. However, studies have shown that many patients find being informed of their CKD distressing, even in its early stages. Using existing analyses of disease in the philosophy literature, we argue that the most prevalent diagnoses of CKD are not, in fact, diseases. We conclude that, in many diagnosed cases of CKD, diagnosing a patient with a "disease" is not only redundant, but unhelpful.

Health as a clinic-epidemiological concept

I propose a clinic-epidemiological concept of health as the best description of what physicians actually think about health within medical practice. Its aim is to be an alternative to the best approach in the philosophy of medicine about health, Christopher Boorse's biostatistical theory. Contrary to Boorse's 'theoretical' approach, I propose to take health as a practical clinical concept. In the first two parts of the paper, I will present my complaints against Boorse's view that health is a theoretical concept, a 'species normal functional ability'. I will claim that Boorse's view is actually a view on normal physiology. My claim is that health is best described as the state of absence of chronic diseases or disabilities (clinic-epidemiologically associated with a morbimortality index higher than the risk of death, disease and disabilities for individuals of the same population group or reference class free of that chronic clinical conditions). Health, therefore, is not the mere absence of disease. Diseases that do not increase patients' morbimortality and disability indexes are not incompatible with health; after all, clinical health is compatible with appropriate health care and medical treatments.

Naturalism about health and disease: adding nuance for progress

The literature on health and diseases is usually presented as an opposition between naturalism and normativism. This article argues that such a picture is too simplistic: there is not one opposition between naturalism and normativism, but many. I distinguish four different domains where naturalist and normativist claims can be contrasted: (1) ordinary usage, (2) conceptually clean versions of "health" and "disease," (3) the operationalization of dysfunction, and (4) the justification for that operationalization. In the process I present new arguments in response to Schwartz (2007) and Hausman (2012) and expose a link between the arguments made by Schwartz (2007) and Kingma (2010). Distinguishing naturalist claims at these four domains will allow us to make progress by (1) providing more nuanced, intermediate positions about a possible role for values in health and disease; and (2) assisting in the addressing of relativistic worries about the value-ladenness of health and disease.