Dien Ho’s title eloquently captures what is at stake in A Philosopher Goes to the Doctor: to take medicine down from the epistemic pedestal on which we are prone to place it. This does not mean that Ho sets out to meet the enterprise of modern medicine with deep skepticism; on the contrary, he bluntly states in his introduction that “modern medicine is great because it works and it is based on science” (p. 2). Instead, he wants to question what exactly makes medicine “a science” and what, by extent, “being based on science” means for the production of knowledge in medicine. This not only has far-reaching implications for research, but also for the practice of medicine itself. Ho’s deconstruction of medicine is therefore always informed by the aim to reconstruct it as more self-aware of its scientific status. In the best of cases, this would lead, as Ho predicts to what he calls “a philosophically informed medicine,” “one that is tolerant, open-minded, transparent, and humble.” And, as he forcefully lays out in the book, “these traits stem not from some vague commitment to political virtues; instead, they come from understanding the limits of what we can know” (p. 150).

The aim to make visible numerous uncertainties and complexities is what drives Ho’s detailed critique of the methods and practices that define modern medical science. In chapter 1, he addresses the distinction between science and pseudo-science by contextualizing it within debates in the history and philosophy of science, which take him from Hume via Popper to Kuhn’s undoing of the heroic narrative of scientific progress itself. Ho reminds us that one of the critical questions we have to answer for ourselves is what precisely it is we want medicine to deliver and then determine how and if medicine is getting us there. Taking the example of how drastically child mortality has decreased in the past 200 years, Ho concedes that medicine may have played a role in improving the lives of children (p. 22), but raises doubts about whether we can take this as ‘evidence’ that medicine works. Proposing a more moderate view of medicine’s contribution to the increase of life-expectancy, he unearths the larger question—one that he returns to repeatedly throughout the book—of whether longevity means that we are truly better off and living more meaningful lives now. Certainty, both at the level of medicine’s role in prolonged life-spans or at the micro-level of scientific methodology, emerges as a profoundly fragile concept in medicine. Ho engages with the long philosophical tradition of thinking about it, as well as pointing to the broader existential questions that it raises. He, thereby, makes the essential conceptual point that the philosophy of science needs a firmer place in scholarship on ethics and the practice of medicine itself.

The second chapter appropriately turns to the concept of health. Although clinical medicine’s ultimate aim is to improve our wellbeing, research medicine’s goal is to produce empirical knowledge. Ho relates this dichotomy to the broader division between normativism and naturalism. He highlights that “if medicine cares only about improving our wellbeing via medical means, then whether disease and health are ultimately grounded in some value-free objective fact becomes far less relevant” (p. 41). At the same time, he makes clear that the two goals are interrelated and that “how we integrate and translate these two parts of medicine with their different understandings of disease and health is an important question that carries significant ethical weight” (p. 42). At this point, Ho mentions the concept of “translational ethics,” which seeks to fill the epistemological gap between research medicine and clinical practice. Given how fundamental the dichotomy is to many issues that Ho discusses in the book, I would have liked to spend some more time on concrete examples that illustrate what kind of interventions translational movements undertake and how precisely they mediate between theory and practice. It also made me wonder whether other concepts of health, beyond the normativism/naturalism dichotomy—such as the physician and philosopher’s Georges Canguilhem’s view of health as adaptability, Hans-Georg Gadamer’s hermeneutic or Havi Carel’s more recent phenomenological account—could have constituted important counterpoints here. Although these indubitably lie beyond the analytic scope of the book, concepts of health no longer conceived of as fixed entities, but as lived experiences, are in a privileged position to mediate between the two goals of medicine Ho is considering here.

In the three subsequent and interlinked chapters on evidence, explanation, and probabilities, Ho sets out to unpack how scientific reasoning in medicine works and what “psychological biases, communal pressures, and financial incentives” (p. 64) play a role in the system of knowledge production on which it relies. “Medical research is at a moment of self-reflection” (p. 46), he poignantly remarks, holding the emergence and success of evidence-based medicine responsible for steering medicine away further from confronting the boundaries of the knowledge it seeks to create. This has far-reaching implications as it further contributes to the proliferation of a “culture of defensive medicine” (p. 90)—the prescriptions of tests and treatments of marginal use, undertaken to limit legal liabilities and often not with the patients’ best interests in mind. If we want to restore trust in medicine, we paradoxically need to challenge the stories that medicine is telling us, a prominent one of them being that of the randomized control trial (RTC), the so-called gold standard of medical research. Ho is not arguing for the uselessness of RCTs. Instead, he alerts us to the many ways in which RCTs create “feedback loops where experimental results are accepted because our metaphysical narrative tells us that we have controlled for all plausible cofounders and the results of the experiment in turn further confirm the legitimacy of the narrative” (p. 60). Taking the classic example of a doctor offering a patient a treatment with a specific success rate, Ho urges us to consider the complexities of interpreting results and translating probabilities. He spells out problems associated with study design and research methodologies and highlights how they get further amplified once they become the basis for clinical practice. Ho’s simple and accurate conclusion is that we need to push for more scrutiny concerning results and methods, that we also need to be able to put these in proper contexts and that “the philosophical uncertainty between evidence and hypotheses should translate into a healthy degree of epistemic humility” (p. 58).

An overarching question of the book is therefore what values drive medicine. In the final two chapters, Ho convincingly lays out why medicine can never be value-free, showing that even if it were, that would not make it harm-free. Values themselves are not the problem though, but that “we behave as if values can be checked by reasons” (p. 129). The failure to recognize values for what they are, Ho warns, is “not only a bad case of denial, it does a moral disservice to everyone involved” (p. 148). Instead, we should recognize the presence of values, and this is of particular relevance for clinical encounters. The triumph of autonomy in bioethics has played no small part in facilitating the culture of defensive medicine, as a consequence of which patients’ values are often and unquestioningly prioritized. Ho certainly does not plead for a return to medical paternalism. Still, he makes the point that clinical medicine should “openly recognize the importance of the values of all parties involved” (p. 130, my emphasis). The question then becomes what the values we want in medicine are. Ho does not give us a conclusive answer, but presumes that the values we adopt in other areas of life, such as “social justice, quality of life, individual autonomy, social stability” are likely to be the ones we want in both research medicine and clinical practice.

A Philosopher Goes to the Doctor is a remarkably rich, thoughtful, and well-written book that has the ambitious aim to make philosophical concepts that drive medicine accessible to non-philosophers. I would argue, however, that it is particularly relevant to medical ethicists. Not only because my review cannot do justice to the way Ho’s writing brims with empirical examples from medical ethics, as well as many other fields, but primarily because it puts forward a systematic rethinking of medicine itself. This is an opportunity for medical ethics to revisit some of its own arguments based on the destabilization of the very concepts that supposedly support medicine as a science. The link that Ho establishes between uncertainty and epistemic humility is one such example because the power of that connection can only be sustained if the conceptual union between the philosophy of science and medical ethics that Ho sets up is pushed further—both in research and in practice.

Most importantly, perhaps, A Philosopher Goes to the Doctor could not be a timelier contribution. I read it as part of an online book club organized by my Institute during the Swiss lockdown caused by the COVID-19 pandemic. These recent events—from the frenzied search for a vaccine to debates over the efficacy of face masks, from racial discrimination in treating COVID-19 patients to what values should drive preventive measures for the next pandemic—confirmed in the most fundamental ways, how necessary the book’s argument about the role of uncertainty and complexity in medicine is. If crisis really does drive reform, then it can only be hoped that A Philosopher Goes to the Doctor will be the starting point for a reckoning with the role and aim of research medicine and clinical practice, and that this can be communicated in and outside of medicine itself.