What Makes Medical Knowledge: On the Epistemological Tensions between “Evidence-Based Medicine” and “Personalized Medicine”

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Liam G. McCoy



“Evidence-Based Medicine” (EBM) and “Personalized Medicine” (PM) are both complex, multifaceted movements with significant implications for 21st century medicine’s approach to medical evidence and clinical decision making. Both movements entail a specific vision for an ideal of medicine, as well as recommendations for practices to achieve this ideal. Each movement also implicitly and explicitly involves its own competing set of epistemological assumptions regarding the nature of medical knowledge, which act to inform (and are themselves informed by) these ideals and practices.

These differences in epistemological perspective manifest as multiple tensions between EBM and PM. The movements differ substantially in their approach to the respective roles of theory and evidence in medical knowledge, in some ways echoing the long-standing “empiricism vs rationalism” tensions in Western philosophy. They also differ in their assessments of the nature of medical uncertainty, and of the level of statistical heterogeneity in patient responses. These conceptual differences manifest methodologically as differences in approach to aggregate vs individualized analyses, including subgroup analyses, and in practice as different views regarding individualization and standardization in medical care. 

This work engages in a brief exploration of the history and nature of these movements and explores these conflicts from epistemological and practical perspectives, as well as the potential for a complementary synthesis between the two. While EBM and PM have substantial points of conflict, they are not necessarily fundamentally incompatible. The movements must work to actively examine their epistemological assumptions, and engage meaningfully with criticisms in order to define the best path forward for 21st century medicine’s relationship with evidence, knowledge, and decision-making.