Death is life’s ending. Let us say that vital processes are those by which organisms develop or maintain themselves. These processes include chemosynthesis, photosynthesis, cellular respiration, cell generation, and maintenance of homeostasis. Then death is the ending of the vital processes by which an organism sustains itself. However, life’s ending is one thing, and the condition of having life over is another. ‘Death’ can refer to either.
Let us add that ‘the ending of life’ is itself potentially ambiguous. On one hand it might be a process wherein our lives are progressively extinguished, until finally they are gone. On the other it might be a momentary event. This event might be understood in three ways. First, it might be the ending of the dying process—the loss of the very last trace of life. Call this ‘denouement death’. Second, it might be the point in the dying process when extinction is assured, no matter what is done to stop it. Call this moment ‘threshold death’. A third possibility is that life ends when the physiological systems of the body irreversibly cease to function as an integrated whole (defended, for example, by Belshaw 2009). Call this ‘integration death’.
Thus death can be a state (being dead), the process of extinction (dying), or one of three events that occur during the dying process. Death in all of these senses can be further distinguished from events—such as being shot with an arrow—that cause death.
1 The Permanence of Death
‘Death’ is also unclear in at least two ways. First, the concept of life is not entirely clear. For example, suppose we could construct a machine, the HAL 1.01, with (nearly) all of the psychological attributes of persons: would HAL 1.01 be alive? To the extent that we are puzzled about what life entails, we will be puzzled about what is entailed by the ending of life, that is, death. (For accounts of life, see Van Inwagen 1990 or Luper 2009.) Second, it seems somewhat indeterminate whether a temporary ending of life suffices for death, or whether death entails a permanent loss of life. Usually, whenever a creature’s life stops, the condition is permanent; so ‘death’, as commonly used, need not be sensitive to the distinction between the temporary and permanent ending of life. Yet life may stop temporarily: a life might be suspended then revived. Or it might be restored. Life in the case of seeds and spores is suspended indefinitely. Freezing frogs and human embryos suspends their lives, too. Suppose that I were frozen and later revived: it is tempting to say that my life stops while I am frozen —I am in a state of suspended animation. But I am not dead. Now imagine a futuristic device, the Disassembler-Reassembler, that reduces me to small cubes, or individual cells, or disconnected atoms, which it stores and later reassembles just as they were before. Many of us will say that I would survive—my life would continue—after Reassembly, but it is quite clear that I would not live during intervals when my atoms are stacked in storage. I would not even exist during such intervals; Disassembly kills me. After I cease to exist, presumably I cannot be revived; nor can my vital processes be revived. If I can be Reassembled, my life would be restored, not revived. Restoration, not revival, is a way of bringing a creature back from the dead.
Assuming that creatures whose lives are suspended are not dead, but creatures who are Disassembled are dead even if later Reassembled, it might be best to say that a creature has died just when its vital processes are irreversibly discontinued, that is, when its vital processes can no longer be revived.
.2 Death and What We Are
Death for you and me is constituted by the irreversible discontinuation of the vital processes by which we are sustained. This characterization of death could be sharpened if we had a clearer idea of what we are, and the conditions under which we persist. However, the latter is a matter of controversy.
There are three main views: animalism, which says that we are human beings (Snowdon 1990, Olson 1997, 2007); personism, which says that we are creatures with the capacity for self-awareness; and mindism, which says that we are minds (which may or may not have the capacity for self-awareness) (McMahan 2002). Animalism suggests that we persist over time just in case we remain the same animal; mindism suggests that we persist just when we remain the same mind. Personism is usually paired with the view that our persistence is determined by our psychological features and the relations among them (Locke 1689, Parfit 1984).
If we are animals, with the persistence conditions of animals, our deaths are constituted by the irreversible cessation of the vital processes that sustain our existence as human beings. If we are minds, our deaths are constituted by the irreversible extinction of the vital processes that sustain our existence as minds. And if persistence is determined by our retaining certain psychological features, then the loss of those features will constitute death.
These three ways of understanding death have very different implications. Severe dementia can destroy a great many psychological features without destroying the mind, which suggests that death as understood by personists can occur even though death as understood by mindists has not. Moreover, human beings sometimes survive the destruction of the mind, as when the cerebrum dies, leaving an individual in a persistent vegetative state. It is also conceivable that the mind can survive the extinction of the human being: this might occur if the brain is removed from the body, kept alive artificially, and the remainder of the body is destroyed (assuming that a bare brain is not a human being). These possibilities suggest that death as understood by mindists can occur even though death as understood by animalists has not (and also that the latter sort of death need not be accompanied by the former.)
.3 Death and Existence
What is the relationship between existence and death? May people and other creatures continue to exist after dying, or cease to exist without dying?
Take the first question: may you and I and other creatures continue to exist for some time after our lives end? The view that death entails our annihilation has been called the termination thesis (Feldman 2000). The position that we can indeed survive death we might call the dead survivors view. The dead survivors view might be defended on the grounds that we commonly refer to ‘dead animals’ (and ‘dead plants’) which may suggest that we believe that animals continue to exist, as animals, while no longer alive. The idea might be that an animal continues to count as the same animal if enough of its original components remain in much the same order, and animals continue to meet this condition for a time following death (Mackie 1997). On this view, if you and I are animals (as animalists say) then we could survive for a time after we are dead, albeit as corpses. In fact, we could survive indefinitely, by arranging to have our corpses preserved.
However, this way of defending the dead survivors view may not be decisive. The terms ‘dead animal’ and ‘dead person’ seem ambiguous. Normally, when we use ‘dead people’ or ‘dead animal’ we mean to speak of persons or animals who lived in the past. One dead person I can name is Socrates; he is now a ‘dead person’ even though his corpse surely has ceased to exist. However, in certain contexts, such as in morgues, we seem to use the terms ‘dead animal’ and ‘dead person’ to mean “remains of something that was an animal” or “remains of something that was a person.” On this interpretation, even in morgues calling something a dead person does not imply that it is a person.
What about the second question: can creatures cease to exist without dying? Certainly things that never were alive, such as bubbles and statues, can be deathlessly annihilated. Arguably, there are also ways that living creatures can be deathlessly annihilated. It is plausible to say that an amoeba’s existence ends when it splits, replacing itself with two amoebas. Yet when amoebas split, the vital processes that sustain them do not cease. If people could divide like amoebas, perhaps they, too could cease to exist without dying. (For a famous discussion of division and its implications, see Parfit 1981.)
.4 Criteria for Death
Defining death is one thing; providing criteria by which it can be readily detected or verified is another. A definition is an account of what death is; when, and only when its definition is met, death has necessarily occurred. The definition offered above was that a creature is dead just when the vital processes by which it is sustained have irreversibly ceased. A criterion for death, by contrast, lays out conditions by which all and only actual deaths may be readily identified. Such a criterion falls short of a definition, but plays a practical role. For example, it would help physicians and jurists determine when death has occurred.
In the United States, the states have adopted criteria for death modeled on the Uniform Determination of Death Act (developed by the President’s Commission, 1981), which says 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.” In the United Kingdom, the accepted criterion is brain stem death, or the “permanent functional death of the brain stem” (Pallis 1982).
These current criteria are subject to criticism. Animalists might resist the criteria since the vital processes of human beings whose entire brains have ceased irreversibly to function can be sustained artificially using cardiopulmonary assistance. Mindists and personists might also resist the criteria, on the grounds that minds and all psychological features can be irretrievably destroyed in human beings whose brain stems are intact. For example, cerebral death can leave its victim with an intact brain stem, yet mindless and devoid of self-awareness.