What does the future hold for psychiatry? 

Since the National Institute of Mental Health declared its independence from the Diagnostic and Statistical Manual of Mental Disorder with the introduction of the Research Domain Criteria (RDoC) research programme, psychiatry and its philosophy have been embroiled in what some have called a ‘paradigm change’ – a move away from descriptive discrete psychological categories, towards lower-level causal accounts. ‘Levels of Analysis in Psychopathology: Cross-disciplinary perspectives’ explores a diverse set of theoretical challenges facing contemporary psychiatric practice, science and nosology. Edited by philosophers and psychiatrists Kenneth S. Kendler and Josef Parnas, and philosopher and psychologist Peter Zachar, this comprehensive volume stays true to its cross-disciplinary billing. The philosophically minded psychiatrist or psychiatrically minded philosopher will no doubt find it a valuable resource. 

The volume is divided into three parts (I, II and III) and each part is, in turn, divided into an uneven number of ‘sections’. Each section contains three individual chapters consisting first in an introduction by one of the volume’s editors, a main paper provided by one of the volume’s contributors, and a subsequent discussion or commentary provided by another contributor. 

Each main paper included in this volume began as a presentation at a three-day conference entitled ‘Multiple Levels, Explanatory Pluralism, Reductionism, and Emergence’ which was held in May 2018 in Copenhagen. The structure of the volume (with its three parts, constituent sections, introductions and discussion notes) is intended to mirror to some extent the discursive back-and-forth format of the original Copenhagen meeting. This is largely successful, however with the book’s 15-page general introduction as well as particular introductions individually opening each of the book’s 15 sections, the experience of is one of much summarising and perhaps less discussion, or at least explicit debate, than would have been ideal. The running discussion and commentary does however successfully provide a kind of ‘narrative spine’ situating the individual contributions within a more cohesive whole. In what follows, I give a short overview of the book’s 15 sections before considering sections 7 and 9 in more detail. 

Part I, ‘Neuroscience, Mechanisms and the RDoC’, kicks off with section 1 in which William Bechtel argues that psychiatric disorders may be explainable in terms of disruptions in control mechanisms. In section 2, Robert M. Bilder provides a perspective on levels and the RDoC, taking lessons from its Working Memory domain, before, in section 3, Daniel S. Pine considers the move towards neuroscience in psychiatry. Part II is entitled ‘Phenomenology, Biological Psychiatry and the Mind-Body Problem’. It starts, in section 4, with Shaun Gallagher on body self-awareness. In section 5, John Cambpell assesses the role of inferred mental causation in psychiatry, before, in section 6, Josef Parnas and Maja Zandersen consider selfhood and identity in the context of schizophrenia spectrum disorders. In section 7, Gregory A. Miller and Morgan E. Bartholomew discuss eliminative reductionism and the RDoC.  

Most of the volume’s contributions are contained within part III: ‘Taxonomy, Integration, and Multiple Levels of Explanation’. Peter Zachar begins, in section 8, with a defence of descriptive psychopathology. In section 9, Kathryn Tabb (one of very few female contributors to this volume) asks whether psychiatry should be precise. Jan-Willem Romeijn and Hanna M. van Loo, in section 10, take a statistical approach to psychiatric classification and, in section 11, Kenneth F. Schaffner provides a clarifying discussion of levels of analysis in psychiatry. James Woodward continues with paper on levels and causation in section 12, followed in section 13 by a more historical perspective and contribution provided by Kenneth S. Kendler. In the two final sections, Stephan Heckers discusses types of reductionism in psychiatry in section 14 and Eric Turkheimer closes in section 15 with biological psychiatry and its explanatory pitfalls.  

I very much enjoyed Miller and Bartholomew’s defence of the RDoC as a non-reductionist initiative. The authors contend that the RDoC has returned psychology to the forefront of psychiatric research and theorising via its central emphasis on psychological constructs. This is not usually how the issues is framed so Miller and Bartholomew’s perspective here is interesting and thought-provoking. As the authors imply, and as Zachar indeed notes in his comments, the degree to which the RDoC is problematically or naively neuro-reductionist often seems rather exaggerated among philosophers, perhaps mainly for reasons of overall signalling, rather than any substantial feature of the RDoC or particular commitments of its developers.  

Miller and Bartholomew’s discussion of whether and to what extent mental disorders are brain disorders is comparatively confused. As Zachar indeed notes, it is very unclear how, as the authors allege, the status of depression as a mental disorder rather than a brain disorder can be a matter of logic. I suppose what Miller and Bartholomew have in mind is that ‘being a mental disorder’ is somehow entailed by the semantics of our concept of ‘depression’ but Zachar is right that this is pretty muddy philosophical territory. Besides, if such an implication was clearly entailed by our concept, shouldn’t its status as a mental disorder be entirely uncontroversial? 

Kathryn Tabb’s paper also is also interesting. Tabb provides an illuminating take on the complex, and perhaps sometimes unfortunate, interdependence between metaphysical problems in psychiatry (for example, the theoretical prospects for neuro-reductionism) and deeply practical, pragmatic concerns. Tabb suggests that the messaging surrounding the RDoC and similar precision-oriented initiatives has caused concerning alterations in economic priorities downstream, such as funds being diverted from psychosocial public-health oriented research and towards so-called ‘basic science’. Tabb’s point here is both well-argued and, I think, a pertinent caution for our times. 

Clinical neuroscientist and RDoC workgroup participant Robert M. Bilder’s takes a very different approach to these issues in his commentary. Bilder accuses Tabb of tearing down a straw-man in place of the RDoC and the Precision Medicine Initiative (PMI). For example, in response to Tabb’s suggest that precision medicine in psychiatry requires joint adherence to the three basic principles of reductionism, nosological revisionism and big data, and that they cannot be treated individually, Bilder denies any necessity in this ‘bundling’ of priorities. Moreover, Bilder contends, the evidence of adverse impacts in terms of funding remain unclear. 

I think Tabb may similarly be in danger of overstating the degree to which the RDoC has a problem with demarcation – that is, distinguishing disorders from non-disorders. Tabb argues that, regardless of how well we come to understand the sources of variations in mental functioning, it will never deliver us clarity as regards to the normative issue of what is and is not a mental disorder. 

Even if this is true (and it is not so clear that it is – is perfect knowledge of how the liver normally functions useless for understanding when it is diseased?), this problem is not unique to the RDoC. Although our intuitions may be less clear in psychiatry, any attempt at nosology in medicine suffers an in-principle inability to provide a robust criterion of demarcation (precisely because, as philosophers know, there is little consensus here). Arguably, because the RDoC is geared towards understanding the full spectrum of neuropsychological functioning, from healthy to pathological, it is relatively well positioned, at least in the short term, to circumvent any problems arising from lack of clarity as regards the concept of disorder – contrast this with the DSM which purportedly only describes what counts as pathology.

This tendency is perhaps not unique to Tabb, but I am concerned that she mischaracterizes the commitments of the RDoC in this respect. For example, Tabb cites Jerome Wakefield’s insistence that the RDoC is committed to conceptualising mental disorder as, simply, high neural circuit activation. I have however never seen a citation or direct quote of any RDoC developer or champion actually defending this implausible view – as Wakefield rightly notes, anyone who’s ever had an orgasm knows it to be false. (This is not to say that such sources do not exist, but it is notable in any case that neither Wakefield nor Tabb refers to them.) 

Similarly, Tabb attributes to the RDoC the fallacious view that abnormal functioning is ipso facto pathological functioning. She extrapolates this position from the following quote: ‘(t)hen, in this light, mental disorders (will be) considered as extremes at one or both tails of these normal distributions’ (Cuthbert & Insel, 2010 cited in Tabb, 2020, p. 326). But, arguably, the formulation ‘one or both’ indicates precisely that Cuthbert and Insel are providing for there being cases where statistical extremes of functioning (such as high IQ, a counter-example which Tabb notes) do not constitute medical disorder. Whether or not demarcation is a problem for the RDoC programme at this early stage, its conceptual naivety seems rather overstated. 

In sum, the book’s editors and contributors work have been successful in producing a comprehensive, genuinely interdisciplinary volume fielding an impressive range of perspectives, knowledge-bases and academic backgrounds. It makes for a compelling read. Researchers in this field, from across the disciplinary spectrum, will no-doubt be stimulated by the high-level discussions and forceful debate, and postgraduate students in the philosophy medicine and psychiatry will find it an excellent resource for deepening their knowledge and understanding of contemporary theoretical and philosophical problems in psychiatry and mental health. 

Sources

Wakefield, J. C. (2014). Wittgenstein’s nightmare: why the RDoC grid needs a conceptual dimension. World Psychiatry, 13(1), 38.

Cuthbert, B., & Insel, T. (2010). The data of diagnosis: new approaches to psychiatric classification. Psychiatry: Interpersonal and Biological Processes, 73(4), 311-314.

Harriet Fagerberg is a PhD student in philosophy at King’s College London and Humboldt-Universität zu Berlin. She is associated with the Sowerby Philosophy & Medicine Project at King’s and the Berlin School of Mind and Brain at Humboldt.