 Most discussions of the definition and determination of death assume that there is a uniquely correct definition of death. Definitions, classically understood, are supposed to state necessary and jointly sufficient conditions for the correct application of a word or concept. They may be thought to capture de re essences existing independently of human thought, language, and interests, or de dicto essences determined solely by linguistic meaning. The major approaches we have considered have tried both to define death by capturing its essence and to advance a standard for determining human death that coheres with the definition. But what if the term “death” cannot be defined in any such way?