Rationality is a key value in the management of health systems.
It is at the very heart of the rationalization project of western care systems and is referred to as the ultimate criterion in evaluation of world ethnomedicines. We argue here that the the main contribution of anthropology to the analysis of the place of rationality in ethnomedicinal knowledges and practices remains in the critical analysis of three reified mirages of rationality. These are the mirage of irrational beliefs as empiricist propositional statements, as products instead of as acts of language, the mirage of the systematicity and coherence of the interrelations linking those beliefs and the mirage of consistency between practices and goals or of the universality of instrumental reason. In order to go beyond a simple critique of the abuses of rationality, we propose that anthropology must go above and beyond the debate on the formal criteria defining rationality of practices and the logics of knowledges. It must redefine ethnomedical knowledges not as a product empirically expressed through a constellation of beliefs, even if systematically organized, but as a process of interpretation and explanation of illness and sickness.