<span style="mso-ansi-language:EN-US">There is an apparent consensus in philosophy of medicine that conceptualanalysis has led to a stalemate regarding the definitions of health anddisease. Rather than accepting this view and abandoning attempts to definethese concepts, I consider whether a more biologically nuanced approach isneeded. More precisely, I scrutinize the idea that understanding biologicalnorms in terms of variation and variability helps to clarify the concepts ofhealth and disease. In this dissertation, I explore how the work of GeorgesCanguilhem seeks to follow this path. In the first chapter, I differentiateCanguilhems biological genealogy of medical concepts from conceptual analysisto specify how his approach differs from many others in analytic philosophyof medicine. The second chapter then goes further into Canguilhems critique ofthe idea that disease is merely a deviation from normality and shows how hisviews differ from a standard naturalist approach as found in Christopher Boorse.After establishing that, for Canguilhem, biological norms should be understoodrelative to individual organisms in their environments, the third and fourthchapters address some criticisms leveled at his eco-organismic approach, suchas whether his account misunderstands biological individuality, whether theconcepts of health and disease need only apply to individual organisms, andwhether he places too much emphasis on individual organisms for understandinghow (evolutionary) biology can clarify health and disease. Together, these twochapters serve as a heuristic for clarifying many concepts within Canguilhemsphilosophy and allow me to show how these criticisms miss the mark. AsCanguilhem argues for the environmental relativity of biological and medicalnorms, the fifth chapter considers whether some environments are more importantthan others by looking at the ideas of Darwinian medicine. I show that whileevolutionary accounts of health and disease help to clarify the various causesof disease, they struggle to provide clear definitions of health and disease.As health and disease are likely best understood relative to presentenvironments and current physiological norms, it seems that Canguilhems eco-organismicrelativity remains quite relevant. In chapter six, I tie together the precedingarguments with a more detailed analysis of Canguilhems organismic andenvironmental relativity and show how his views on health and disease can beupdated by looking at some concepts from ecological developmental biology:phenotypic flexibility and biological robustness. While this provides aninteresting way to naturalize the concepts of health and disease, I also showthat Canguilhems view is limited when it comes to finding a way tooperationalize or measure these concepts. The final chapter explores somepotentially problematic conclusions that result from relativizing health anddisease when it comes to human social environments. I analyze the idea ofsocial pathologies and consider how social norms contribute to the experienceof disease. As a whole this dissertation suggests that a more biologicallynuanced approach to health and disease seems needed to push the debate inphilosophy of medicine further and that some insights into how this could beaccomplished can be found in the ideas of Canguilhem.