Until recently, "brain death" was widely regarded as one of the crowning conceptual achievements of bioethics. After all, less than four decades after the whole-brain criterion of death was first proposed, it has come to supplant the traditional, cardiopulmonary criterion of death throughout much of the world. Not only doctors but also lawmakers and religious authorities have embraced the view that we die when our brains irreversibly cease to function, not, as earlier times had it, when our hearts and lungs irreversibly cease to function. This revolution in our thinking about human death has had profound practical implications. It has opened the way to vital organ donation and unilateral withdrawal of treatment from patients with beating hearts but no hope of recovering brain function.
In recent years, however, the whole-brain criterion of death has come under increasing criticism, and a growing consensus has developed among bioethicists and philosophers that brain death is actually incoherent. While the proponents of brain death have typically defended it on the grounds that the brain is necessary for the integrated functioning of the organism as a whole, recent findings appear to contradict this claim. (1) Furthermore, extensive study of the "brain dead" has shown that even after the standard battery of diagnostic tests for brain death has been fulfilled (including documentation of coma, the absence of brainstem reflexes, and the absence of respiratory effort), many brain functions persist--including such presumably integrative functions as hormone secretion and thermoregulation. (2)
These apparent inconsistencies have led even one of brain death's most prominent defenders to admit that "Brain death was accepted before it was conceptually sound." (3) I will argue in this paper that, while the whole-brain criterion of death is roughly correct, the conceptual framework that its advocates have appealed to is deeply philosophically flawed. In their arguments in support of the whole-brain criterion, the advocates of brain death have appealed to a misguided philosophical model of what is required for the justification of a criterion of death, which their opponents have adopted and turned against them. This model depends on some claims about language that, while initially plausible, have been seriously undermined by Ludwig Wittgenstein, Saul Kripke, and Hilary Putnam, whose arguments most philosophers of language regard as decisive. Drawing upon their insights, and also upon promising recent work in the philosophy of biology, I propose a new model for our understanding of life and death, which I argue provides a more secure justification for the whole-brain criterion.
The Challenge to the Whole-Brain Criterion
According to the whole-brain criterion of death, a person dies when the whole brain irreversibly ceases to function. Coma, absence of respiratory effort, and absence of brainstem reflexes are the standard tests for the loss of whole-brain function. The two main alternatives to the whole-brain criterion are the higher-brain criterion and the traditional cardiopulmonary criterion. Advocates of the higher-brain criterion claim that it is not the irreversible loss of the functioning of the whole brain, but only of the neocortex--the part of the brain responsible for consciousness, memory, personality, and perception--that is necessary and sufficient for death. This criterion would only require permanent unconsciousness for the declaration of death, dismissing lower-brain functions such as respiratory drive and brainstem reflexes as irrelevant. Advocates of the cardiopulmonary criterion, on the other hand, claim that the irreversible loss of circulatory functioning and the irreversible loss of respiratory functioning together are necessary and sufficient for death. As the cardiopulmonary criterion is usually interpreted, it does not matter whether these functions are carried out spontaneously or via external measures (such as a ventilator or chest compressions). …