The individual relativity of health and disease: Personalized medicine in the light of Canguilhem's philosophy of medicine

Résumé En

The progress of so-called “personalized medicine”, in particular in the context of the development of targeted therapies in oncology, leads to more precise definitions, diagnostics and treatments of diseases. This could give rise to the constitution of ever smaller classes of diseases. Further, via an approach that aims to be both dynamic and holistic, “systems medicine” and in particular “P4 medicine” (preventive, predictive, participative, and personalized) advocates an individualization based on observation of the transition between health and disease for each individual, thanks to repeated monitoring of various genomic, clinical, psychical, environmental, and social characteristics. These different forms of individualization echo the theses of Canguihem, according to which there is no general definition of the normal and the healthy but only a universal biological normativity, which, in each biological individual, takes an individual form. That idea led Canguilhem to affirm the impossibility both of a science of the normal and the pathological and of complete objectivity with regard to these phenomena. Systems medicine, by contrast, and in particular P4 medicine, promotes both a quantification and a science of well-being. The aim of this chapter is to examine the forms of individualization of health and disease which give rise to the two principal orientations of personalized medicine – the stratified medicine, the precision medicine, already used in oncology, and the more theoretical systems medicine – and then to confront them with Canguilhem’s thesis regarding health and disease. In this way, I will develop a critical analysis of the promises and pretentions of personalized medicine, and in particular P4 medicine.