Ken Kendler is one of the most widely respected and highly prolific academic psychiatrists of our times. He is well known to readers of this journal for his work as an editor, and he is well known throughout the field for his work on DSM. What is particularly fascinating about his cutting-edge contributions is how they stretch from empirical research – mainly work on twin and molecular studies, through to conceptual work – on philosophy and history of psychiatry.

This volume integrates Kendler's interests, showing how his thinking bridges empirical and conceptual work. The volume also tells us a good deal about Kendler the man; Zachar's biography and Kendler's introductions to each reprint of one of his papers help us understand the context of his work, and this, in turn, helps us to get to grips with his ideas, and the way in which they have developed, in a way that a straightforward collection of his articles would not achieve.

There are a number of reasons that this volume is a major contribution to the field.

First, conceptual issues are crucial in everyday practical psychiatric diagnosis and assessment, research on etiology, and treatment. We need sharper ways of thinking about DSM decision-making (why is homosexuality out, and behavioral addiction in?), about research methods (do we use DSM criteria for genetic research? What will the Research Domain Criteria framework achieve?), and treatment planning (do we give medication or psychoanalysis? Some sort of combination?). Kendler provides the sharpest thinking about these debates that is currently available.

Second, conceptual debates in philosophy of psychiatry are often either overly strident or overly dry. Anti-psychiatry makes important points about the limitations of psychiatry, but it is often overly critical and quite impractical. Work on the philosophy of medicine and psychiatry addresses important topics but is often written in the dull genres of analytic philosophy or the abstruse genres of continental philosophy. Kendler's thinking has much in common with American pragmatism: the genre is clear and readable, in line with its practical aims. Kendler provides the most on-the-ground approach to philosophy of psychiatry currently available.

Third, conceptual debates in philosophy of science have tended to focus on physics as a key exemplar, one that is too removed from the world of biology and medicine to be useful for psychiatry. Kendler, again in line with American pragmatists, such as John Dewey, is particularly interested in the intersection between philosophy and biology, including both physiological mechanisms and evolutionary mechanisms. He may not be the first to state some of his important take-home messages, but he is likely the first to articulate them in a way that draws so tightly on such a rich database of psychobiological data, much of which he has personally collected.

What are the important take-home messages of the volume? The volume has a wealth of ideas, and different ones will resonate for different readers. For me, two or three related themes stand out.

First, Kendler's view of psychiatry is anti-essentialist and anti-reductionist. Mental disorders are not comprised of a particular ‘essence’, and they are not caused by a single gene. Rather, mental disorders are complex entities, and they involve multiple causes acting at different levels of reality. Reification of diagnostic criteria and over-reliance on monocausal explanations discourages good clinical practice. Furthermore, some questions in psychiatric nosology cannot be resolved by science alone, they require value judgements. This view complements a good deal of recent work in philosophy of psychiatry on the relevance of values, by authors such as Fulford and Sadler (Fulford, Thornton, & Graham, Reference Fulford, Thornton and Graham2006; Sadler, Reference Sadler2005).

Second, and relatedly, Kendler emphasizes the importance of pluralistic and multi-level explanations of mental disorders. A tradition dating back to Karl Jaspers argues that in psychiatry we need both mechanistic explanations and human understanding. For some years, perhaps the most practical introductory volume to the philosophy of psychiatry was McHugh and Slavney's ‘The Perspectives of Psychiatry’, which also falls in this tradition (McHugh & Slavney, Reference McHugh and Slavney1998). Kendler moves this tradition forward in a sophisticated, nuanced, and up-to-date way, introducing, for example, the notion of ‘explanation-aided understanding’, based on contemporary neuroscience.

Third, and again relatedly, Kendler is a fallibilist, who emphasizes that current nosological solutions (e.g. DSM-5) and neurobiological theories (e.g. the dopamine theory of psychosis) are based on current knowledge, that they are only one possible approach of many, and that we need to revise them as we learn more. Again, this approach is nicely aligned with the tradition of pragmatism; we have a working approach to clinical and research questions, but as we experiment in and with the world, we develop a more fine-grained knowledge of relevant mechanisms, and we revise our approach.

Foundational conceptual questions are perhaps more acute when one is a trainee, grappling with the question of which supervisor is telling the truth – a respected older psychoanalytic supervisor advising that additional psychotherapy is needed, or an ambitious young M.D.-Ph.D. clinician-scientist advising pharmacotherapy augmentation. And they are also more acute at particular times for the field as a whole: when a new set of critiques of psychiatry gains attention, when a new version of our diagnostic manual is published, when there is a new slew of papers on the genetic architecture of mental disorders. Kendler's rigorous work, and his nuanced approach, may be particularly useful at such times.

Any quibbles? My view is that the volume is important enough that it deserves a sharper title. Arthur Kleinman's ‘Rethinking Psychiatry’ did just that (Kleinman, Reference Kleinman1988). Kendler's work, analogously, involves reconceptualizing psychiatry. In addition, one of the most interesting lines of development of early pragmatism has been the contemporary focus on ‘embodied cognition’. My view is that this body of work sheds light on several of the questions that Kendler asks, and comes to not dissimilar conclusions (Stein, Reference Stein2008). Given that this work is also based on empirical data, it could perhaps be usefully integrated into a Kendlerian view.

Kendler tells lots of stories to make his points. It would be remiss of me not to mention that I first met Ken as a junior resident, sitting in Bob Spitzer's office, as he was making a call to ask for advice about how to operationalize bizarre delusions. I was impressed that Bob, a demi-God for me back then, was so respectful of Ken's views, and could only imagine how much knowledge this disembodied voice represented. As I have gotten to know Ken over the years, meeting him in the context of work on DSM-5, on psychiatric epidemiology, on neurogenetics, and at one of his philosophy conferences, he has met every expectation I could possibly have had: Ken embodies the most advanced empirical and conceptual knowledge of contemporary psychiatry. I would wager that he would also be the first to admit, with his customary twinkle in the eye, that this would be just a snapshot, good for today.