The reflections put forward in this text concern the clinical and practical difficulties posed by the existence of patients in PVS, and the essential ethical issues raised, combining these ethical questions with practical and theoretical experience. Section 1 presents the methodology of the ethical reflection as we see it. Section 2 describes the clinical condition of patients in PVS. Section 3 develops the ethical difficulties relative to PVS from the French point of view. Section 4 illustrates the relevance of debating the ethical significance of such problematic situations, whilst defending a practical position based on a philosophical conviction. Section 5 points out the limits of ethical reflection in a biomedical context, and calls for reflection closer to the source of the problems described. For a comprehensive appraisal of biomedical rationality, the final section suggests combining the bioethical debates with traditional philosophical ethical reflection so as to get a clearer understanding of the real, if limited, relevance of these debates.