What is death? Eric Olson, University of Sheffield

1. Death and life

If we’re going to spend the whole semester talking about death, we ought to know at least roughly what death is. As it happens, it’s not easy to say. What death is is one of the interesting philosophical questions about death that this module is devoted to exploring.

One answer is easy and uncontroversial: death is the opposite of life. More precisely, it’s the end of life. So

A thing dies when it ceases to be alive.

This has two important implications. First, life and death are exclusive: nothing can be both alive and dead at once. (Otherwise a thing could be dead without ceasing to be alive.) Second, life and death are not exhaustive: some things are neither alive nor dead. A thing that has never been alive--a stone, say--cannot be dead. Death is not mere absence of life, and eing dead is not the same as being nonliving. Life and death are like green and red: you can’t be both, but you can be neither.

So we know that death is the end of life. That makes death a negative concept. In order to know what death is, we need to know what it’s the end of. We need to know what it is to be alive. Life and death are opposites, but life is the more fundamental concept: death is defined in terms of life but not vice versa. What is life, then? What is it about you and me that makes us alive? What is it about a stone or a corpse that makes it not alive?

2. The biological conception of death

One attractive answer is that life is a sort of physical process or activity. What distinguishes living things from nonliving ones is that they take in new matter, impose on that matter a complex form characteristic of the organism, and then expel it in a less ordered form. What’s more, these activities are to a large extent coordinated. This coordination promotes the continued life of the whole organism. An animal’s digestive system extracts nutrients from its food, and these nutrients are distributed, by means of the bloodstream, to the entire animal: the digestive organs don’t keep the nutrients for themselves. Likewise, a tree’s leaves produce nutrients by photosynthesis, and these are distributed throughout the tree. Waste products inimical to healthy functioning, such as carbon dioxide and urea, are 1 eliminated from the organism, not just shifted to other areas. A living thing is a system of many parts that cooperate to keep the system going. When these activities cease, the organism begins to decay. This is something that modern science has discovered. If this is what life is, it follows that the cessation of these activities is death.

Roughly, then, thing is alive just if certain biological activities are going on within it-- when it is biologically functioning, we might say; and a thing dies when it ceases to function in that way. The precise nature of this activity or functioning is complex, and is the subject matter of physiology, anatomy, biochemistry, and related sciences. It’s understood in considerable detail. But we know that it has to do with things like metabolism, respiration, circulation, nutrition, elimination of waste, and fighting off infection. So:

A thing is alive when (and only when) it is functioning biologically. A thing dies when it ceases to function biologically.

Call this the biological conception of death. It has two important consequences. First, it seems to imply that death is univocal. There is only one sort of death, and it applies to all living things alike. That sounds right: when we say that Aunt Petunia has died, and when we say that the petunias in her garden have died, we seem to be saying the same thing about the woman and her plants. They’ve both died. We don’t seem to be saying that Aunt Petunia has died in one sense of the term while the flowers have died in another sense. Both human beings and plants are alive in the same sense, and thus they die in the same sense.

Second, it seems to imply that death is in no way a psychological phenomenon. The biological functions that life consists in are not mental functions. So death may cause the permanent loss of consciousness, but they’re not the same thing. This would seem to follow from the claim that death is univocal. Plants have no mental lives, and their death is not a psychological phenomenon. If we die in the same sense that they do, then our death should not be a psychological phenomenon either.

3. The psychological conception of death

The biological conception of life and death may sound uncontroversial. It’s roughly the sort of thing you read in biology textbooks, and one version of it or another figures in the legal definition of death in every country on earth. However, it has its critics.

One worry is that the biologial conception, in the seemingly uncontroversial terms 2 in which I’ve stated it, is vague. It tells us only roughly what it is for a thing to be dead or alive, and leaves the details unspecified. And the details can be important. When an organism starts doing badly, the biological activities that make up its life do not all stop at the same time. If someone’s heart stops beating and never begins again, breathing will stop immediately, but the cells will continue to absorb oxygen from the blood and to secrete carbon dioxide. Soon cells will begin to die, but they don’t die all at once. Brain cells die sooner; other cells survive longer. That’s why organ transplants are possible for several hours after the brain has been destroyed: the cells in the kidneys and the cornea, for instance, remain alive.

So consider someone whose brain has altogether stopped functioning because its cells have all died, but whose kidney cells are for the most part still living and functioning. The person appears to be partly biologically functioning and partly not biologically functioning. Is she alive or dead? The biological conception of death doesn’t say--or not, anyway, unless we make it more precise. But making it more precise will make it more controversial. These precise details are the subject of most disputes about definitions of death. (DeGrazia’s article in the SEP is a good overview of this rather tedious topic.)

But there is a deeper worry about the biological conception. Maybe it’s a mistake to characterize life in biological terms in the first place. Maybe we should characterize it in psychological terms. There are certain psychological activities, or psychological functions, that characterize human beings: broadly speaking, thought and consciousness. Normally these psychological functions go on for as long as our biological functions do: you remain conscious and thinking until your respiration and circulation stop and your remains begin to decay. But sometimes the psychological activities stop while the biological activities carry on.

An extreme case of this sort is called persistent vegetative state. This happens when the upper brain--the bit responsible for thought and consciousness--is destroyed (usually by lack of oxygen), but the lower parts of the brain, which direct our life-sustaining functions such as breathing and circulation, remain intact. Human beings in a persistent vegetative state can often breathe, digest food, and perform all the other biological functions characteristic of life with no artificial assistance. They need only be fed and cleaned. But they are completely incapable of thought, awareness, or action. Nor can they ever regain those capacities. They can remain in this state for many years.

Are human beings in a persistent vegetative state alive or dead? They may be alive in some sense, but in another, more important sense, you might think, they’re dead. Suppose you were told that someone you love had had a heart attack and is now in a persistent vegetative state. The medics have established that there is no 3 chance that he or she can ever regain consciousness: the part of the brain responsible for consciousness is simply destroyed and cannot regenerate. Probably you would react much the same as you would if you were told that she was dead. ‘Poor Aunt Petunia,’ you would think. ‘She’s gone. That’s the end of her.’ You would consider her dead even though she may still be breathing without any assistance. Though she may not be legally dead, she’s as good as dead-- dead for all practical purposes. (Or nearly all: we can’t yet send her remains to the mortuary for burial or cremation.) Grief and mourning are appropriate responses.

Why would you take your aunt to be dead, or as good as dead, in this case? Well, think of why we care about life and death. What’s the point of being alive? Why do we prefer that we and our loved ones remain alive, in normal cases, rather than dying? It doesn’t matter much whether someone is left-handed or right-handed. It matters more whether someone is male or female. But none of these differences matter anywhere near as much as the difference between being alive and being dead. Why?

The reason, or at least the main reason, seems to be that many things we value are possible only when we are alive. We like to be happy. We enjoy feeling pleasure and satisfaction. We enjoy setting ourselves goals and working to achieve them. We enjoy watching movies, joking with our friends, cuddling with our lovers, seeing and doing and tasting new things.... We could continue the list indefinitely. There are all sorts of things we love doing. These are the things that give us a reason to get out of bed in the morning (though we may also enjoy lying in and resting peacefully). But you can’t do any of these things if you’re dead. Why is that?

Well, because all these things require conscious awareness. You can’t feel pleasure or enjoy your favourite activity or joke with your friends if you’re completely unconscious. They also require other mental properties: having preferences and intentions and beliefs, for instance. And you can’t have any conscious awareness or intentions or beliefs or preferences when you’re dead. That’s what we hate about being dead. And that’s why we want to remain alive: because being alive is necessary for our existence to have any value for us. It would be good for you, I assume, for you to live for another ten years. It would not be good for you to be in an irreversible vegetative state for ten years, followed by death in the biological and legal sense.

So everything that matters in life, it seems, requires thought and consciousness. (I mean ‘thought’ in a minimal sense: having preferences counts as thought.) It requires mental activity. This suggests that maybe death is not the cessation of biological functions, but the cessation of mental functions. Death is not a biological event, but a psychological one. (Maybe psychological events are a special case of 4 biological events. That would make death a biological event. But what makes that event death would not be its biological features, but rather its psychological features. Death is still primarily psychological, and it’s biological only insofar as psychology in human beings is a special sort of biological activity.)

If death is the end of life, this would mean that it was a mistake to characterize life as a sort of biological activity involving respiration, circulation, metabolism, and other nonmental functions. Life is rather a sort of psychological activity. Or perhaps a sort of psychological capacity: you don’t die when your mental activities stop completely, as long as this stoppage is reversible, as in deep sleep or general anaesthesia. The proposal, then, is this:

A thing is alive when (and only when) it has the capacity for mental functioning. A thing dies when it loses the capacity for mental functioning.

Call this the psychological conception of death. (I will set aside worries about whether someone who loses the capacity for some but not all mental capacities is alive or dead.)

The psychological conception has important and controversial implications. Most obviously, it does not apply to all living things. Trees have no capacity for mental functioning. There is no psychology of trees. It follows that according to the psychological conception of death, trees cannot die. They can’t die because they were never alive. Most of what biologists call living things, in fact, are not really alive and cannot die.

Another controversial implication is that life does not begin at conception, or anywhere near it. Your psychological life did not begin until five or six months after conception at the very earliest (maybe later, depending on what sort of mental activity is required for psychological life). According to the psychological conception of death, a five-month-old human foetus is not dead, but not alive either. And because it’s not alive, it can no more die than a stone can. Abortion does not kill anything.

Or suppose there is life after death. More precisely, suppose that when we die, we continue to exist, in a conscious state and able to remember our natural lives (so that there is no period of nonexistence separating death from resurrection). In that case, it would follow from the psychological conception that no one ever dies. The event we call death is not really death at all, because we don’t then lose the capacity for mental functioning.

And of course there is clearly a sense in which a human being in a persistent 5 vegetative state is not dead, but very much alive--just as much alive as an oyster or an oak tree is alive. One day--when its biological functions cease--it will die. Until that happens we couldn’t bury it, or take it to the crematorium for burning.

4. Pluralism about death

These look like serious objections to the psychological conception. One way of defending the psychological conception is to argue that it’s not actually in competition with the biological conception. There are two kinds of death. We might call them biological death and psychological death. The biological conception is an account of biological death, whereas the psychological conception is an account of psychological death. And likewise there are two kinds of life, biological life and psychological life. Some things are alive only in the biological sense: trees, oysters, bacteria, and so on. Other things are alive in the psychological sense: most human beings, apes, and probably dogs and birds and other vertebrates. (How far down the Great Chain of Being psychological life extends depends on exactly what mental functions are necessary for it.) There might perhaps be beings that are psychologically but not biologically alive: gods or angels or spirits, or intelligent, conscious electronic computers.

Human beings (most of them, anyway) enjoy both biological life and psychological life. That makes us subject to both biological and psychological death. In most cases these two events occur at the same time, but sometimes, such as persistent vegetative state, psychological death occurs first and biological death occurs later-- sometimes many years later. (If there is life after death, biological death occurs before psychological death.) So trees die one death; we human beings die two deaths. We might call this view pluralism about death (or, if you like big words, ‘thanatological pluralism’).

It would mean that biological life begins at or near conception, whereas psychological life begins when the foetus or infant acquires the relevant psychological capacities. And it would mean that if there is life after death (and immediately following death), then what we call death really is biological death, though it is not psychological death.

(Or maybe a human being does not die two deaths. Rather, what we call a human being is really two things: a person, who dies only in the psychological sense and then ceases to exist, and an organism, which dies only in the biological sense. So the death of a person is a completely different sort of thing from the death of a tree or a dog or even a human organism. This would mean that Aunt Petunia and the petunias in her garden cannot both die in the same sense. To say that both Aunt Petunia and her flowers have both died would be a sort of joke. It would be like 6 saying that Peter went clubbing and lost two things: first he lost his head and then he lost his wallet. This would not follow from pluralism as originally described. It would also mean that human organisms have no psychological life. They are no more conscious or intelligent than stones. And human people have no biological life: they are no more biologically alive than stones. What appears to be a single thing that is both living in the biological sense and thinking is really a biologically living but unthinking thing and a thinking but nonbiological thing. This is a version of substance dualism. I will say no more about this view.)

5. Death as the departure of the soul

I’ve considered these proposals:

• A being dies when it ceases to function biologically. • A being dies when it ceases to function psychologically. • There are two sorts of death. A being dies in the biological sense when it ceases to function biologically. A being dies in the psychological sense when it ceases to function psychologically. But there is no single, unified concept of death.

But there is another proposal that at least sounds very different from these: death is the departure of the soul from the body. This used to be a widely held view, and many religious believers continue at least to say it. But whether the view really is different from the others, whether it’s widely held, and whether it’s plausible, depends on what the view actually is. What does it mean to say that someone’s soul departs from her body? What is a soul, and what is it for a soul to depart from someone’s body? Until we have answers to these questions, there is no point in trying to evaluate the view that death is the departure of the soul.

Many people speak of the soul without having any clear idea what the term means. And I think most talk of the soul outside of academic philosophy and systematic theology is literally meaningless. It has no content at all, or at best very little. There’s just no saying what would follow from ordinary statements about the soul.

But some who speak of the soul know exactly what they mean by it. Aristotle thought the soul was a sort of configuration or organization of a thing’s matter. In that case, to say that someone’s soul has departed from her body is just to say that her matter has ceased to be configured or organized in a certain, special way. The departure of the soul from the body is roughly just the cessation of biological or psychological functioning. That would make the soul view entirely compatible with the views we’ve already considered.

7 Plato and Descartes have a very different view of the soul: it is an immaterial thinking being. It is immaterial in that it is not made of matter--the stuff that makes up material things such as sticks and stones. Plato and Descartes thought that only an immaterial thing--a soul--could think or be conscious or have any mental property. What’s more, they thought that a soul can exist and continue to think and be conscious independent of any material thing. Even if you are physically destroyed--if you make a blunder while attempting to defuse a powerful bomb, say-- your soul can continue to exist and to function psychologically.

While you are alive, Plato and Descartes thought, your soul is ‘in’ your body--your body meaning a biological organism. Not spatially within it, since the soul has no spatial location. Rather, your soul is ‘united with’ your body in the sense of being in two-way causal interaction with it. Stimulation of your sense organs causes sensations or perceptual states in the soul: for example, my soul gets visual sensations as a result of the patterns of light falling on my retinas. That’s what enables me to see. My soul gets other sensations when my other sense organs are stimulated, enabling me to hear, feel, smell, and so on. By this means I get knowledge of the world by perception. So the body can act on the soul. Likewise, the soul can act on the body: if I decide to raise my arm--an event in my soul--it results in my arm’s rising. That’s what enables me to act physically.

For a soul to be ‘in’ a body, then, is for it to be able to perceive via the body’s sense organs and to move the body just by intending to move. For the soul to ‘depart from’ the body is for this two-way interaction to be lost. So the proposal is this:

A being dies when an immaterial thinking thing loses its capacity to perceive via the being’s sense organs and to move the being’s body just by intending to move.

Call this the Platonic conception of death. It’s definitely different from the other proposals. Because the soul has nothing to do with biological functioning, it could depart from the body while your biological functioning continues as before. So a being in a persistent vegetative state (or perhaps we should say, ‘a being whose body is in a persistent vegetative state’) would be dead on the Platonic conception, but not on the biological conception. And because a soul can continue to function psychologically apart from the body, you could die according on the Platonic conception without dying according to the psychological conception.

The Platonic view shares some of the disadvantages of the psychological conception of death. Most obviously, it implies that most living things cannot die, since they haven’t got immaterial souls. It would be no more possible for a tree or an oyster to die than for a stone to die. For that matter, it would be impossible for a 8 human being in an irreversible vegetative state--a being that breathes and engages in all the other life-sustaining functions without any artificial life-support--to die. But some of these disadvantages could perhaps be mitigated by combining the Platonic conception of death with pluralism.

The main objection to the Platonic conception is that there don’t seem to be any souls in Plato’s sense. It doesn’t appear to be the case that thinking, conscious beings are immaterial entities, and that no biological organism can think or feel pain. Yet the Platonic conception implies that there are such souls. Or if there aren’t, it follows that no one can die, even if they cease to function both biologically and psychologically.

To my mind, the best proposal is the biological conception of death. And that’s the one favoured by most philosophers, as well as by the legal systems of all countries I know of.

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