Paper: The C-word, the P-word, and realism in epidemiology

My paper ‘The C-word, the P-word and realism in epidemiology‘ is now available online.

Citation

Broadbent, A. The C-word, the P-word and realism in epidemiology. Synthese (2019). https://doi.org/10.1007/s11229-019-02169-x

Abstract

This paper considers an important recent (May 2018) contribution by Miguel Hernán to the ongoing debate about causal inference in epidemiology. Hernán rejects the idea that there is an in-principle epistemic distinction between the results of randomized controlled trials and observational studies: both produce associations which we may be more or less confident interpreting as causal. However, Hernán maintains that trials have a semantic advantage. Observational studies that seek to estimate causal effect risk issuing meaningless statements instead. The POA proposes a solution to this problem: improved restrictions on the meaningful use of causal language, in particular “causal effect”. This paper argues that new restrictions in fact fail their own standards of meaningfulness. The paper portrays the desire for a restrictive definition of causal language as positivistic, and argues that contemporary epidemiology should be more realistic in its approach to causation. In a realist context, restrictions on meaningfulness based on precision of definition are neither helpful nor necessary. Hernán’s favoured approach to causal language is saved from meaninglessness, along with the approaches he rejects.

Book published: Philosophy of Medicine

My book Philosophy of Medicine (Oxford University Press) has now been published in the USA, and in paperback in the UK. Hardback date in the UK is 28 March. E-books are of course available.

I am putting together a series of YouTube videos corresponding to each of the chapters, by way of segue into the fourth industrial revolution.

The book carves out some new territory in the field, by taking a broad view of medicine as something existing in different forms, in different times and places. I argue that any adequate understanding of medicine must say something about what medicine is, given this apparent variety of actual practices that are either claimed to be or regarded as medical. I argue that, while the goal of medicine is to cure, its track record in this regard is patchy at best. This gives rise to the question of why medicine has persisted despite being so commonly ineffective. I argue that this persistence shows that the business of medicine – the practice of a core medical competence – cannot be cure, even if that is the goal. Instead, what doctors provide is understanding and prediction, or at least engagement with the project of understanding health and disease.

I also cover the familiar question of the nature of health. The naturalism/normativism dichotomy is a false one, since it elides two dimensions of disagreement, one concerning objectivity, the other concerning value-ladenness. It is obvious that these are logically distinct properties. I argue that health is a secondary property, like colour, consisting in a disposition on our part to respond to an underlying reality which, however, does not carve the world in the way that our responses do. The reason that we have this disposition to respond to the underlying properties rather than some other – the reason that we have this particular health concept – is the advantages it conferred on groups of humans during our evolutionary history. My secondary property view sees health as a non-objective but non-evaluative property, and this places it in a previously unoccupied portion of the logical space created by distinguishing clearly between the dimensions of traditional disagreement.

The second part of the book concerns the attitude we should have towards medicine, and is informed by the understanding of the nature of medicine developed in the first part. Evidence Based Medicine and Medical Nihilism are discussed. The former sets high standards for what counts as evidence. The latter basically accepts these standards and then argues that so little medical research meets these standards that we should despair of medicine, and regard even apparently well-supported interventions as probably ineffective. Both views are rejected on their merits, but a connecting theme is their location of the whole value of medicine in its curative powers. I see value in medicine beyond cure, and thus even if the arguments of EBMers and nihilists succeeded on their merits (which I deny), they would not warrant such a negative attitude to the majority of medicine.

Philosophy of medicine has had little to say about non-Mainstream traditions, beyond occasional spats with alternative therapists. The last three chapters of the book seek to remedy this. A view called Medical Cosmopolitanism is advanced (inspired by Kwame Anthony Appiah’s book and ethical position Cosmopolitanism) as an alternative to the evidence-basing and nihilistic stances. The main tenets are realism about medical facts, especially what works, epistemic humility when discussing these facts, and the primacy of practice – focusing on specific problems rather than grand principles. Realism means that we should not shy away from trying to determine whether one or another intervention is better; we should not have a “hands off” approach, even where deep and/or cultural beliefs are at stake. Epistemic humility means that when approaching disagreements we must be mindful of the less-than-distinguished history of medical claims, and must be respectful, tentative, open to changing our mind. The primacy of practice is the idea that we focus first on what to do in particular cases, since agreement here is usually easier than on larger principles.

I then apply this position to medical dissidence and decolonization of medicine. Medical dissidence occurs when traditions co-exist with a more dominant tradition and reject parts of it. Homeopathy is the paradigm case. I advocate a much more tolerant stance between disputants about alternative medicine, arguing that the reason for different views (also extending to topics such as vaccination) is that all of our medical evidence reaches us through testimony, and trust then becomes king-maker as to which medical evidence you accept. It’s no good telling someone that a trial was fantastic if they just don’t believe you, and nor are they irrational to reject evidence from a trial if they just don’t believe that the trial occurred, or was fair, or similar. Unless you run a trial yourself, you are in the position of receiving your medical information second-hand, and then trust relationships become paramount. This patchy history of medical success amply explains why trust in any given tradition might be hard to come by.

Finally, contact between medicines deriving from different cultures presents interesting epistemic and practical challenges. In former colonies, these challenges must be handled carefully. Medicine is imbued with culture, and to insist on one medicine over another can be culturally oppressive. At the same time, cosmopolitanism is committed to realism. So, no matter how deeply held a belief in the efficacy of a certain intervention or ritual, if this ritual does not work or is less effective than one provided by Mainstream Medicine (as I call it – since it is no longer strictly Western) then this fact must be confronted. Moreover, ordinary people just want efficacy: we can quibble at the periphery, but fundamentally, illness is a universal human experience, as is holding a sick child in your arms. Thus I advocate something a little more critical than “dialogue” between traditions. I invite a critical attitude. The approach must be humble, and Mainstream Medicine must concede that it may well have something to learn from, e.g., African Medicine. But decolonization must fundamentally consist in the adoption of a critical mindset, one that rejected political colonization, and that goes on to reject epistemic colonization. This critical mindset demands that African, Chinese, Indian and other traditions take the inevitable confrontation with Mainstream Medicine seriously, and seriously consider whether their various interventions and strategies are effective, just as they ask Mainstream Medicine to take these interventions and strategies seriously.