Caveat: I am no scientist. If details of the following are in error, please let me know.
Brain death is one of the conceptual foundations of organ transplantation. If the person from whom the surgeon takes a beating heart is not dead before surgery, he will be dead after and the surgeon will be guilty of a direct act of killing. For some, the good of organ transplantation justifies a shift from cardiac to neurological definitions of death. According to a 1968 report by a Harvard committee studying the subject, brain-based definitions of death were developed to make it easier to "pull the plug" without the danger of killing the patient and to provide legal and moral warrant for transplanting unpaired vital organs.
This morality-by-redefinition was, however, unsatisfactory to the transplant surgeon whom I heard speak awhile back. An evangelical Christian, he argued that the destruction of the brain is the moment "when the soul leaves the body," and the organs of a soulless body are there for the taking. Yet, that formula too raises a number of theological and practical difficulties. It assumes a Cartesian dualism of soul and body, with the soul conceived as something of a ghost peering out from within the bodily machine. Practically, it leaves the bodies of mentally handicapped and brain-damaged persons vulnerable to horrific exploitation. If the brainless are soulless, why not genetically manufacture anencephalic fetuses to serve as organ factories?
Perhaps these are not the strongest rationales for equating brain death with death, but, according to a lengthy article by D. Alan Shewmon in the Linacre Quarterly (1997), few strong reasons — medical, moral, or philosophical - are available. Shewmon, a Professor of Pediatric Neurology at the UCLA Medical School, traces the path that led him from the conviction that "the death of the brain is the death of the human organism" to the conclusion that "brain death is not death," a path he describes as a "recovery from brain death." Shewmon's views on the subject should carry considerable weight, for he has spent much of his academic career developing a medical and philosophical expertise on the problems surrounding brain death; in 1985 he published an article in The Thomist offering a thought experiment to demonstrate the equivalence of brain death with death and he defended this view into the 1990s. Shewmon's defection, moreover, requires substantial conviction and courage, for the medical community has often been dismissive of the "simpletons and physiological heretics" who question the brain death orthodoxy. Given the stakes in debates over life and death, Shewmon's Apologia takes on far more than autobiographical significance.
The bulk of the article describes Shewmon's efforts to come to terms with nagging medical evidence that cast doubt on the equation of brain death with death and, more broadly, on two accepted "facts" of neurology. The first is that the brain is the "central integrator of the body," coordinating and controlling individual organs and systems by receiving information and sending signals through the nervous system. On this assumption, when the brain is destroyed, the body "would no longer be a 'body,' strictly speaking, but a collection of juxtaposed organs that may superficially interact for a time but are actually in an early phase of disintegration."
Second, neurologists distinguish the functions of the cerebral hemispheres, especially the neocortex, as the locus of consciousness, from the brain stem, which is the center of lower level brain activity (arousal). This distinction is the basis for the idea of a Persistent Vegetative State (PVS), in which the patient combines a functioning brain stem with loss of cortical functioning and, ostensibly, a loss of consciousness. Combined, these two claims justify the use of brain death as a clinical indicator of death. As Shewmon himself wrote in 1992, "the combined arguments of loss of somatic unity and loss of essential human properties [are] compelling reasons to accept the equivalence between total brain destruction and death."
Despite near unanimity among neurologists on these points, Shewmon came to reject both of these "facts." Two hydranencephalic children who displayed obvious signs of consciousness, despite having no cortical functioning, challenged the idea of the cortical basis of consciousness. He finally rejected the claim that the brain is the central integrator of the body after involvement in the case of a fourteen-year-old boy whose body functioned for nine weeks on minimal artificial support after he was pronounced brain dead. Though properly diagnosed as brain dead, the boy "seemed to be somatically thriving" with "many signs of integrative unity and life at the level of the 'organism as a whole.'" He recovered from pneumonia several times and "even began puberty" in this condition. Eventually, Shewmon concluded that "not all biological integration requires an integrating organ . . . integration can consist simply in the mutual interaction among multiple tissues and organ systems." Scientifically, the evidence that "brain death is not death" seems strong.
More than scientific evidence is at stake, however. Though he rejects the conclusion that "the demise of 'brain death' automatically implies the demise of vital organ transplantation," Shewmon draws the ethical inference that "many transplant operations do involve the direct killing of the donor, especially when the beating heart is excised." Such direct killing, whatever the intentions of the parties, is "an objective evil" that erodes respect for human life.
Few of his colleagues are willing to accompany him to this point. When Shewmon presented his new views on brain death at the Second International Symposium on Brain Death in 1997, the response was "both gratifying and disturbing: gratifying in that many of the North American delegates seemed to accept my arguments that 'brain death' is not, after all, death of the biological human organism; disturbing in that many also seemed to regard that as irrelevant to the problem of human death."
Instead of focusing on the medical evidence, debate now centers on the issue of personhood, with death defined as loss of personhood, that is, loss of consciousness. Quite logically, a 1993 survey of neurologists and nursing home medical directors in which "half of the respondents believed that PVS patients should be considered dead and almost two-thirds believed it would be ethical to remove their organs for transplantation."