Department of Philosophy

 

Kenneth Kipnis

Department of Philosophy

University of Hawaii at Manoa

           

 

It is, alas, one of the most familiar things in the world.  Alive one minute, dead the next.  But what exactly happened?

 

On the surface, there has been a dramatic change in social standing: a living human being has become a corpse. The former might have enjoyed rights to health care and legal protections against an array of wrongs. Death makes an end to these, and to marriage, citizenship, and even legal personhood. It is perhaps the most complete and final alteration of status known to law. We can now cut open the body out of intelligent curiosity, burn or bury it; hand it over to medical students for dissection; gather up personal property and distribute it to others, all of which would be grave wrongs if ever done to the living. It is no wonder that premature burials and twitching body bags are the stuff of horror stories. It is no mystery why communities take exquisite care to avoid mistakes that are beyond embarrassing. Because so much hangs on the official pronouncement, only the most knowledgeable are authorized to certify that death has occurred. But what exactly is the warrant for their judgment?

 

Conversations about the definition of death are commonly plagued by ambiguity in the level of analysis. Beyond the social account set out just above, it is useful to distinguish among four other levels: biological, physiological, clinical and legal. The stories we tell about the nature of death have to have at least that many chapters. 

 

We begin, at the deepest biological level, with the nature of animal life. Herewith a thumbnail history of biological metaphors for the living body.  If, as an animal, our essential Aristotelian nature involves locomotion, then we cease to exist (as animal-natured beings) when our capacity for locomotion ends. But if, as Harvey discovered, we are pulsating, vascularized circulations of life-giving blood, then we cease to exist as living creatures when the vital flow stops. And, finally, if we are wet computers, neurologically connected to input and output peripherals (as many have come to believe) then we cease to exist just when our central processing units fail, permanently and completely.

 

Within each of these three conceptions, the next task is to draw upon physiology (the second level) to define biological death. Breathing is a most subtle locomotion, perhaps the most essential and the last to disappear. We still speak of people “expiring.” So understood, death occurs when respiration ceases. Later on, for theorists following Harvey’s discovery, a person could be said to have died when the essential cardiac pump stopped beating.  No pump, no blood flow, no life.  Finally, for most contemporary theorists, death occurs decisively when the brain (or some substantial portion of it - the jury is still out) dies, even if the heart continues to function. The phone can ring but nobody is home.

 

The third level is clinical. In practice, how should health care professionals determine that the critical physiological state is present. One very old test involved a mirror held near the nostrils. The patient was alive if the glass fogged, dead if it remained clear. Following Harvey, the stethoscope allowed physicians to ascertain the absence of heartbeat, the cessation of circulation and, therefore, death. But the cardiac criterion became problematic perhaps fifty years ago as advancements in resuscitation, life support and surgery allowed patients to survive the stilling of their hearts. People joked about having been dead for twenty minutes, reveling in the patent contradiction. While no dramatic changes in social standing were occurring, it was time to revise the cardiac conception of death. The transition to death by neurological criteria is still evolving.

 

The process began shortly after the first heart transplants, with the 1968 publication in JAMA of the Report of the Ad Hoc Committee of the Harvard Medical School to Examine the Definition of Brain Death. The Ad Hoc Committee urged that death be understood as the irreversible loss of function of the whole brain, including the brain stem. This medical conception was quickly and widely adapted as a legal criterion in the United States. By 1981 the American Bar and Medical Associations had endorsed the Uniform Determination of Death Act which held that: 

 

An individual who has sustained either (1) irreversible cessation of circulatory and respiratory functions, or (2) irreversible cessation of all functions of the entire brain, including the brain stem, is dead. A determination of death must be made in accordance with accepted medical standards.

 

Notice how the new standard is piggy-backed onto the Aristotelian and cardiac conceptions of death. The added definition effectively eliminates the inherent legal risks associated with harvesting transplantable hearts. 

 

Notice also how the language of the Act sets out a procedural criterion for brain death as well as a substantive one. Though irreversible cessation of all brain functions is essential, the determination of brain death requires physician compliance with “accepted medical standards.” As doctors became comfortable with the new definition, gold-standard confirmation by brain-wave and blood-flow analysis fell out of use. Along with some other clinical observations (absence of a gag reflex, unresponsiveness of the pupils to light, etc.), the most dramatic assessment tool has been the apnea test. The unconscious, brain-injured patient is removed from the ventilator for several minutes. If breathing does not begin as the seconds pass -- as carbon dioxide builds up in the blood stream -- doctors can infer the destruction of those brain stem regions governing unconscious respiration. While the law is clear enough about physiology, it hands off the clinical practicalities to physicians. 

 

But islands of neurological activity can persist even when brain death is established according to the accepted tests. The regulation of temperature is one example. When certain neurological structures are disabled, body temperature destabilizes. Clinicians must then use thermal blankets and sensors to heat and cool patients. Despite the legal requirement that there be “irreversible cessation of all functions of the entire brain . . .” death is often pronounced when some brain functions are evidently unimpaired. In these situations, do the physiological or the medical standards have priority? If some activity persists, exactly how much of the brain has to be irreversibly lacking in function before death is present? And how certain must clinicians be that this condition is met?

 

Michael Green and Dan Wikler offered some useful analysis in their 1980 paper, “Brain Death and Personal Identity.” They begin with a rough distinction between the lower brain (including the brain stem) and what we will term the higher brain (including the cerebral hemispheres). The lower brain manages many autonomic biological functions: movement of food through the intestines, breathing while asleep, temperature regulation etc. The higher brain is where personhood is lodged: memories, skills, emotional traces, knowledge, etc. While many have thought that a higher-brain criterion is superior to a whole-brain criterion, in 1968 EEGs could not reliably determine whether weak electrical impulses were emerging from the brain stem or elsewhere. As a practical matter, it made sense to include destruction of the brain stem in the definition of death. It is always safer to err by treating a corpse as a living person rather than risk treating a living person as a corpse.

 

Green and Wikler challenged several standard justifications for the neurological criterion. Some had defended it by pointing out that those declared “brain dead” would shortly be dead by cardiac criteria. But even if some present condition were invariably followed by cardiac death, that would not entail that one were dead already. Some had defended it by noting that those declared “brain dead” could no longer have lives that were subjectively valuable. But even if one no longer cared about being alive (or anything else), that would not entail that one had died (though it might mean that one could no longer be harmed by dying). 

 

Drawing on John Perry’s work in metaphysics, Green and Wikler argued that, despite errors in  the standard justifications, the death of the higher brain really is death. Their reasoning can perhaps be succinctly captured in two thought experiments.

 

1. The Getaway: Pursued by the police for heinous crimes, Moriarty engineers the ultimate escape. Using science fiction technologies, he arranges to have his higher brain transplanted into the skull of Alfred, a kidnapped dustman. Recovering from the surgery, he eventually opens what used to be Alfred’s eyes and continues writing his autobiography using what used to be Alfred’s hand. 

 

It would appear that the police should now be looking for a man with Alfred’s body: i.e., Moriarty. The philosophical implication: personal identity follows the higher brain. 

 

2. The Mishap: In the operating room, Moriarty’s higher brain has been removed and is being carried in a basin to what had been Alfred’s body, with its now vacant cranium. Suddenly the basin-carrier trips, the grey mass launches into the air and breaks into moist fragments as it plops onto the floor.

 

Though what used to be Moriarty’s body is still robust, Moriarty has ceased to exist. The philosophical implication: the death of the higher brain marks the death of the person.

 

Considerations like these, and the scientific findings that make them relevant, are persuasive in showing that higher-brain death marks the end of personal life.

 

But what about those islands of neurological activity in patients who are brain dead according to the tests in current usage? Alas, there is no reliable, quick, cheap and simple way to rule out the presence of potentially functional regions; no neurological analog to the mirror and stethoscope. And even if we could locate and identify the tiniest active areas, we are far from being able to decide what kinds and amounts of neurological activity are compatible with a determination of death.

 

Though neurology has made enormous progress in recent years, we are still importantly in the dark. Our legal systems and medical professions are muddling through the most consequential judgments we will ever face. But while clinicians are probably doing well enough, there is a troubling concern that we have left behind the old paradigms without fully appreciating the life-and-death issues arising out of the new one.

 

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RECOMMENDED READINGS

 

McMahan, Jeff. The Ethics of Killing. Oxford University Press: New York, 2002. Chapter 5, pp. 423-503.

 

Green, Michael, and Daniel Wikler. 1980. “Brain death and personal identity.” Philosophy and Public Affairs 9:105-133.

 

John Perry, ed.  Personal Identity (Berkely and Los Angeles: University  of California Press: 1975).

 

Stuart J. Youngner, Robert M. Arnold, Renie Schapiro, eds. Definition of  Death: Contemporary Controversies, (Baltimore: Johns Hopkins University Press: 1999).

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