The debate opened in 1968, when the Ad Hoc Committee of the Harvard Medical School to Examine the Definition of Brain Death (Harvard Committee) recommended an updating of the criteria for determining that a patient has died. The Harvard Committee put forth a set of clinical tests it claimed was sufficient to determine the death of the entire brain. It then recommended that whole-brain death be considered direct and sufficient evidence of the death of the patient. Thus arose the suggestion, which has become entrenched practice in the United States, that a binary standard be used for determining death: that in addition to the traditional heart and lung criteria still applicable in the vast majority of cases, a whole-brain death criterion be used to determine death for respirator-dependent, permanently unconscious patients.
This was the modest beginning of the so-called definition-of-death debate. Rather than having resolved over the last thirty-five years, this debate has evolved and intensified due to fascinating and complex constellations of philosophical, clinical, and policy disagreements. To best appreciate these disagreements, one must understand the definitional debate as one that has three logically distinct, yet interdependent levels: (1) the conceptual or definitional level; (2) the criteriological level; and (3) the medical diagnostic level. Let us look at each of the three levels in turn.
THE THREE LEVELS OF THE DEBATE. Level One: The conceptual or definitional level. At level one, the question is, What is human death? While some people think basic definitions such as this one are somehow written on the face of reality for our discernment, defining death is in fact a normative activity that draws on deeply held philosophical, religious, or cultural beliefs and values. The definition or concept of death reflects a human choice to count a particular loss as death. The level two and level three activities of deciding which physiological functions underlie that loss (i.e., choosing a criterion for determining death), and of specifying the medical tests for determining that the criterion is fulfilled, are medical/scientific activities. The conceptual question can be answered in a general, yet uninformative way by saying that human death is the irreversible loss of that which is essentially significant to the nature of the human being. No one will take issue with this definition, but it does not go far enough. There is still a need to decide what is essentially significant to the nature of the human being.
People differ radically in their views on the distinctive nature of the human being and its essentially significant characteristic(s). Because their fundamentally different perspectives on human nature flow from deeply rooted beliefs and values, the difficult policy question arises concerning the extent to which a principle of toleration should guide medical practice to honor the alternative definitions of human death that exist.
The discussion later in this section will show that the human being can be thought of as a wholly material or physical entity, as a physical/mental amalgam, or as an essentially spiritual (though temporarily embodied) being. The way the human is thought of will influence the view of what is essentially significant to the nature of the human being, and ground one's view about the functional loss that should be counted as human death. A metaphysical decision concerning the kind of being the human is, is the ultimate grounding for the normative choice of criteria for determining that an individual human being has died. There could be no more interesting or important a philosophical problem, then, than the problem of deciding: What is human death? Why? And, there could be no more interesting an ethical/ policy problem than that of deciding whether and how to tolerate and enable a diversity of answers to these questions.
Level Two: The criteriological level. Based on the resolution of the ontological and normative questions at the conceptual level, a criterion for determining that an individual has died, reflecting the physiological function(s) considered necessary for life and sufficient for death, is specified. That is, the essentially significant human characteristic(s) delineated at the conceptual level is (are) located in (a) functional system(s) of the human organism. The traditional criteria center on heart and lung function, suggesting that the essentially significant characteristics are respiration and circulation. The whole-brain-death criterion is said by its proponents to focus on the integrated functioning of the organism as a whole. The higher-brain-death criterion centers on the irreversible absence of a capacity for consciousness.
Level Three: The diagnostic level. At this level are the medical diagnostic tests to determine that the functional failure identified as the criterion of death has in fact occurred. These tests are used by medical professionals to determine whether the criterion is met, and thus that death should be declared. As technological development proceeds, diagnostic sophistication increases. The Harvard Committee believed that the death of the entire brain could be clinically diagnosed using the tests it identified in its report, and recommended that the whole-brain-death criterion be used to determine death in cases of respirator dependency. However, it provided no conceptual argument (i.e., no answer to the level one question, What is human death?) to support the criterion and practice it recommended.
These three levels—conceptual, criteriological, and diagnostic—provide a crucial intellectual grid for following the complex definition-of-death debate since 1968. The debate encompasses all three levels. In any reading and reflection associated with this complex debate, it is essential to remember what level of the debate one is on, and what sort of expertise is required on the part of those party to the debate at that level. Further, any analysis and critical assessment of suggested criteria for determining death require that one attend to the important interconnections among tests, criteria, and concepts. Criteria without tests are useless in practice; criteria without concepts lack justification. It is the philosophical task of constructing an adequate concept or definition of human death that becomes central to a justified medical practice of declaring death. As Scot philosopher and historian David Hume (1711-1776) said centuries ago, "Concepts without percepts are blind." At the beginning of the twenty-first century, a criterion for determining death without a philosophical analysis of what constitutes death is equally blind. All in all, there ought to be coherence among concept, criterion, and clinical tests. At least this is the way one would normally wish to operate. Among other things, the definition-of-death debate can be expressed as a debate among alternative formulations of death: the traditional cardio-pulmonary, whole-brain and higher-brain formulations.
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