Before discussing ethical issues to do with patients in permanent (or persistent) vegetative state (PVS) it is necessary to address the foundational issue of whether PVS as a concept is able to provide a robust link to situations in the real world. The high reported rates of misdiagnosis and recovery in patients diagnosed as being in PVS casts doubt upon the applicability of ethicists' thought experiments on Platonic forms to actual decision making in clinical situations. We should abandon the illusion that we can have access to logical certainty through diagnostic definition, and should instead frame our opinions and our procedures in ways that can accommodate a high element of uncertainty, and should in the light of recent studies give considerable weight to the possibility that patients, at present unable to express opinions on their care, will later become able to do so, if given proper treatment and adequate evaluation.