Philosophy of Medicine

What it asks

Medicine identifies conditions, calls them diseases, and treats them. Every step assumes an answer to what a disease is, and no answer is agreed.

One view is that disease is a biological matter: a part is not performing the function it was shaped to perform, statistically relative to the species. That is objective and looks scientific, and it has trouble with conditions that harm nobody and with harmful states that are statistically normal.

The other is that calling something a disease is partly a value judgement about which states are undesirable enough to treat. That fits the history well - homosexuality was classified as a disorder, drapetomania was invented to pathologise escape - and it makes the concept sound arbitrary in a way clinicians reasonably resist.

The recurring problems

Naturalism against normativism. Is disease a purely biological dysfunction, or does the concept contain an ineliminable value judgement? Almost every practical dispute in the field traces back to this.

What counts as evidence. The randomised trial sits at the top of the standard hierarchy, and hierarchies of evidence are themselves philosophical claims about inference. Trials establish average effects in populations; a clinician treats one person, who may not resemble the average.

Causation with populations. A drug raising risk from two per cent to three does not cause any identifiable person's illness. What the causal claim is about, and how it bears on an individual, is genuinely unclear.

Overdiagnosis. Better detection finds conditions that would never have caused harm. Treating them produces harm, and the person treated cannot know they were not helped. This is a live public health problem that is at bottom conceptual.

How it developed

Medicine was long thought to have no philosophy of its own, being applied biology plus ethics.

Two things changed that in the 1970s. Boorse's biostatistical theory in 1977 gave a precise naturalist analysis of disease - dysfunction relative to species-typical functioning - which was clear enough to be argued with, and has been argued with ever since. And bioethics grew fast enough that the conceptual questions underneath it became visible.

Evidence-based medicine in the 1990s made the second half of the field urgent. Placing trial evidence above mechanism and clinical experience was a philosophical position with enormous institutional force, and it was adopted before it was examined.

The examination since has been productive: on when mechanistic evidence should count, on what external validity means, and on why trial results so often fail to transfer to the patients in front of a doctor.

The positions within it

Naturalism and normativism about disease, with hybrid accounts holding that a condition must involve both dysfunction and harm. Evidentialism about trial hierarchies and its pluralist critics. All are in the Schools section.

Where it stands now

The evidence questions dominate now, because they have institutional consequences: what regulators approve, what guidelines say, and what a clinician may do when the trial population is not their patient.

Precision medicine sharpens the tension, since it promises to treat individuals while relying on evidence generated from groups. And the pandemic put the field's methodological questions in front of a general audience for the first time, mostly without acknowledgement that they were philosophical.