Total Brain Death and the Integration of the Body Required of a Human Being

Abstract

I develop and refine an argument for the total brain death criterion of death previously advanced by Germain Grisez and me: A human being is essentially a rational animal, and so must have a radical capacity for rational operations. For rational animals, conscious sensation is a pre-requisite for rational operation. But total brain death results in the loss of the radical capacity for conscious sensation, and so also for rational operations. Hence, total brain death constitutes a substantial change—the ceasing to be of the human being. Objections are considered, including the objection that total brain death need not result in the loss of capacity for sensation, and that damage to the brain less than total brain death can result in loss of capacity for rational operations.

I. INTRODUCTION

Total brain death, or the irreversible cessation of all functions of the entire brain, including the brain stem, is legally accepted as a criterion for death in the United States. ¹ Until fairly recently, the standard rationale for this criterion, as explained for example by the President’s Commission on Determining Death in 1981, was as follows: Because a human being is a particular type of organism, the death of a human being can be defined as, “the permanent cessation of functioning of the organism as a whole” (Bernat, Culver, and Gert, 1981, 391). And because the functioning of the brain is necessary for the integration of the human body—it integrates the various cells, tissues, and organs into a single organism—the complete loss of the functioning of the brain results in the complete loss of integration of the human body and death.

As is well known, in the last two decades D. Alan Shewmon has challenged that argument, attempting to show that the brain is not a necessary condition for the integration of the human body, and to show that in some cases total brain death has not resulted in the permanent loss of the integration of the organism as a whole, that is, that in some cases human beings have in fact survived total brain death, albeit in extremely disabled states. Shewmon seems to have shown that there are counter-examples to the brain death criterion for the death of a human being; that is, he seems to have shown that some human individuals have survived brain death. His evidence seems to show that in some bodies that have suffered brain death, there are many living and holistic functions—functions that belong to the body as a whole, and so—since holistic actions seem to provide evidence of the persistence or survival of the organism—that in some cases total brain death was not the death of the human being. Among such holistic actions are these: homeostasis of a variety of chemicals and physiological parameters, detoxification and recycling of cellular wastes, maintenance of body temperature (although at a lower than normal level), wound healing, and respiration and nutrition (though assisted). In one case, Shewmon describes an individual called “TK” who continued to manifest all those functions for more than 20 years, although his total brain death was confirmed by repeated clinical tests. Such organic actions (Shewmon argues) show that these individuals have survived total brain death, and so total brain death is not a valid criterion for death (Shewmon, 1997; 1998a; 1998b; 2001; Hughes, 2004).

In response to Shewmon, Maureen Condic (2016) and Melissa Moschella (2016) have argued that although some brain-dead bodies do have a type of unity, they lack the specific unity characteristic of organisms. Both Condic and Moschella, in separate papers, have argued that brain-dead bodies lack the unity required of complex organisms. A brain-dead body lacks the global integration required to constitute a unitary, mature organism, but instead, possesses only a unity that arises from the interaction of the multiplicity of cells—the kind of unity observed, for example, in a storm system or in a flock of geese; hence the cells, and not any whole that they compose, are the actual agents or acting substances. Condic and Moschella might be right—and of course, their arguments are much richer than my summary indicates. But the point I argue here is that, whatever the outcome of their arguments, it is clear for a different reason that total brain death is a valid criterion of death. Even if some brain-dead bodies are organisms, or complex entities of some sort, they are not human organisms: They lack the radical capacity for conscious sentience—a prerequisite for rationality in a human being—and so are not rational animals.

Germain Grisez and I have argued that because a human being is a rational animal, and because the total death of the brain entails the entire loss of the capacity for conscious sensation—the radical capacity of which is necessary in order to be a higher animal—the complete loss of the brain entails ceasing to be an organism with the radical capacity for conscious sensation ² and therefore the passing away of the rational animal, the human being (Lee and Grisez, 2012). In this article, I take up this argument again, try to clarify and develop it in relation to other proposals, and consider recent objections. Although I have used much of the basic argument first developed in an article I co-authored with Germain Grisez, I am the sole author here, and so there may be errors and infelicitous expressions for which Grisez should not be blamed.

II. TOTAL BRAIN DEATH IS A VALID CRITERION OF DEATH

Although the argument advanced here does not itself logically depend on thought-experiments about decapitation, still, considering them is helpful as a heuristic device. Suppose a human being, John, is decapitated, but that surgeons work on both the head and the decapitated body so that each survives (the blood vessels are sutured, a heart-lung machine is provided for the head, and a ventilator is provided for the headless body). Obviously, it is impossible that both the head and the headless body are identical with John, since the head is now a different entity from the headless body, and John, if he is still alive, is just one entity. So, either John died, or he is identical with the head, or he is identical with the decapitated body. (I’m supposing that John is, or was, a human organism, and that the human person is a particular type of organism; for a defense of this and a discussion of objections, see Lee and George, 2008, Chapters 1 and 2.)

Moreover, the head and the decapitated body cannot be parts of a single individual. Clearly, the bodily parts of the head and the bodily parts of the decapitated body have no organic union; they do not function together for the sake of the whole of which they would be parts, but function independently of each other. They were, and perhaps in some senses still are, oriented to being joined to each other to function as a single whole, but because they are separated, and now function altogether separately and independently, it is obvious they do not constitute parts of a single entity.

The parts of the surviving headless body (its tissues and organs) have some degree of integration with each other. Could it be a human being? I think the answer is no. And I think the reason why is this. The decapitated body would not be an organism with a capacity for conscious sensation: it would not be a higher animal, and since a human being is a particular kind of higher animal (rational), it would not be a human being. By “higher animal” I mean an animal that has the capacity for conscious sensation—unlike an amoeba or jellyfish, for example, which have the capacity for sensation only in the broad sense of differential response to external stimuli without conscious awareness. ³ A higher animal possesses a capacity for conscious sensation (that is, a capacity to have awareness of the impact on his, her, or its body, of external bodily stimuli, or of internal bodily changes). This capacity may be immediately exercisable (presently exercisable in response to stimuli) or radical (the capacity to develop itself to the stage where it has the immediately exercisable capacity). It need not involve awareness of oneself, but it does involve experience or experiential content. In the early stages of their development, higher animals typically possess only the radical capacity for conscious sensation and at certain times later in their life cycles possess no more than that, due to sickness or injury. Since the decapitated body would lack the capacity for conscious sensation—both an immediately exercisable capacity and a radical capacity—it would not be a higher animal and so not a rational animal, not a human being. But the same point applies to brain-dead bodies. Without a brain, or the capacity to develop a brain, such individuals lack any capacity—whether immediately exercisable or radical—for conscious sensation, and so are not animals, and so not rational animals, not human beings.

The argument I am proposing can be illustrated by considering an explanted organ. Physicians are now able to explant a living lung from a donor (usually after circulatory death) and sustain this living lung for several hours, placing it in a sterile plastic dome attached to a ventilator, maintaining it at normal body temperature, and perfusing it with a solution containing nutrients, proteins, and oxygen. ⁴ Now of course no one would say that a lung sustained outside the body is a human being, and yet it has several functions that seem to belong to it as a whole and its functioning is fully continuous with the human organism from which it came. The lung seems to be in some sense a single, complex entity, maintaining (with assistance) a certain dynamic unity.

In the near future, surgeons will be able to transplant groups of organs that are in close functional cooperation—for example the lungs, heart, and connecting veins and arteries, together as a unit. Now, whether such compounds—the lung and the explanted heart-lung-blood vessel system—should be classified as living individuals or not, it is clear that neither of them is an organism with a radical capacity for conscious sensation, a higher animal. But the status of these integrated systems is relevantly similar to that of brain-dead bodies. Even if brain-dead bodies do possess coordinated living functions of some sort, they are clearly not higher animals, and therefore not human organisms.

The thought experiment about decapitation helps to show that continuity of life functions does not—contrary to what we might first think—indicate that death has not occurred. We might tend to think that the death of a human being must result in a visible discontinuity of basic vital functions, and that since that does not seem to occur in some cases of brain death, then death has not actually occurred. However, no matter how one interprets the scenario of decapitation, it shows that continuity of living operations is not sufficient for the survival of an organism. John cannot be identical with both the head and the decapitated body; and yet there is continuity between John and both. Indeed, when we reflect more on deaths in other cases—ones that clearly result merely in aggregates of organs, tissues and cells—we see that even here there is continuity of vital functioning but not identity of living whole organisms. (Even with explanted organs there seems to be continuity of vital functioning.) With the death of the whole organism, the functioning of resultant lower-level living entities is continuous, but not identical with, the vital functions performed by the organism as a whole before death. Thus, continuity of vital functions does not indicate survival of an organism.

A human being is a rational animal, that is, a higher animal, with a radical capacity for conceptual thought and deliberate choice. The capacities for conceptual thought and free choice are not directly observable by other individuals. However, such actions in human beings presuppose conscious sensation; conceptual thought begins with conscious sensory experience and deliberate choice presupposes conceptual thought. So a human being cannot have a capacity for conceptual thought and deliberate choice without the capacity for conscious sensation, and an organism of the mammalian kind cannot have the capacity for conscious sensation without having a brain or the capacity to develop a brain. In other words, since a human being is a particular kind of higher animal and a higher animal is a sentient organism—an organism with the capacity, at least a radical capacity, for conscious sensory awareness—it follows that an individual that entirely lacks any capacity for conscious sensation is not a higher animal with a capacity for rational action, and so is not a rational animal, not a human being.

One has a capacity to do something if one can do it, given an appropriate environment. One can have a capacity but be impeded from exercising it: Some factor, either internal or external, may prevent one from actualizing what one can do, given one’s internal structure or nature. Now, a living being has a radical capacity for a function if it has within itself a material constitution that dynamically orients and disposes it, given a suitable environment and nutrition, to actively develop (with essentially its own resources) sufficiently to perform that function. For example, immature plants from many species lack an immediately exercisable capacity to reproduce, and yet they have the internal resources to develop themselves to the stage at which they will have all the immediately exercisable capacities of a mature plant of their species. So an organism has a radical capacity for a function, even if it has not yet developed the organs needed to perform that function, if it has, at an early stage of its development, the capacity to develop those organs for itself, given a suitable environment and nutrition.

Human embryos do not have the immediately exercisable capacities for conceptual thought, deliberate choice, or sentient operations such as seeing, hearing, imagining, and so on. But human embryos have within themselves the material resources—the genetic and epigenetic composition and structure—to develop themselves to the stage at which they can perform all of those types of actions. Therefore, human embryos have the radical capacity for sentient and rational actions and so are human beings, and subjects of rights (Lee and George, 2008, Chapter 4).

But if a living being lacks altogether a capacity for conscious sensation—that is, if it lacks an immediately exercisable capacity for conscious sensation and lacks a radical capacity for that—then—since in human beings rational functions presuppose conscious sensation—that living being is not a human being. A totally brain-dead body lacks altogether a capacity for conscious sensation, and therefore is not a higher animal, and therefore not a human being. Such a body could have conscious sensation only if it had a brain (or the capacity to develop a brain); for if it were a higher animal, it would be of the mammalian kind, and a mammal cannot perform conscious sentient functioning without a functioning brain.

Fr. Nicanor Austriaco (2016) has recently argued that brain-dead bodies have not in fact lost their radical capacity for sentience. Lower animals—for example, jellyfish or earthworms—sense without a brain. In brain-dead bodies (he argued), the spinal cord is capable of mediating a differential motor response to sensory stimuli (Knikou, 2010). This has been shown in many experiments in which animals, including humans, with complete spinal cord transection have been trained to step and even modify their gait in accordance with the speed of stepping. These cases show that in some cases the spinal cord responds to afferent stimuli absent any input from the cortex (Behrman, Bowden, and Nair 2006; Lynskey, Belanger, and Jung, 2008). ⁵

However, the kind of activity presupposed by rational actions—the radical capacity for characterizes a human being—is sensory awareness, involving experience or consciousness. This is why in explaining the arguments for the position defended here I have referred to higher animals, that is, organisms with a radical capacity for sensory awareness, or conscious sensation.

The work done with spinal-cord-injured animals shows that the spinal cord builds up complex neuronal circuits that provide patterns of movements as in walking, chewing, and other complex actions. Through habituation the spinal cord generates or modifies such motor neuronal circuits in response to afferent neuronal stimuli. Such actions performed by animals with complete spinal cord transection do seem to indicate sensory function independent of brain function. And yet, developing or altering such circuits in response to neuronal stimuli is not the same as awareness or consciousness of one’s environment or oneself. Although the spinal cord evidently establishes and adapts the central pattern generator in relation to afferent stimuli, patients with spinal cord injury who undergo such training are never directly aware of the sensory stimuli in response to which the spinal cord adapts. Speaking of the noncephalized nervous system of the cubomedusa jellyfish, neuroscientist Bjorn Merker notes that it enables the jellyfish to engage in “flexible directional locomotor responsiveness to asymmetric sensory inputs” (Merker, 2007, 63), and then adds: “There is no reason to assume that the environmental guidance thus supplied by its radially arranged nerve net involves or gives rise to experience of any kind” (Merker, 2007, emphasis added). Essentially the same point applies to the central pattern generator established in the spinal cord. Thus, it might be possible that in totally brain-dead bodies there are nonconscious, spinal-cord-mediated sensations, but that does not provide counter-evidence to the argument presented above to show that such bodies are not human beings.

Philosophers who maintain that the human being is composed of body and soul hold that all of the basic powers of a human being, including his or her powers of conscious sensation, are rooted in the soul, a principle of unity and life, conceived of as an immaterial part of the human being. Someone holding that may object that even though there is no capacity for conscious sensation in the material constitution of some brain-dead bodies, the powers for conscious sensation continue to exist in the soul.

However, a power or capacity to do X is possessed by that which does X. For humans, the human being is the agent, not his or her soul—so it would be a mistake to say that “the soul senses, or exercises vegetative powers.” The soul is that by which the human being is able to do this or that, but the capacities are possessed by, or inhere in, the human being, not his or her soul. Even in intellectual and volitional acts, it is John or Mary, not their souls, that understands or wills, even though the acts of understanding and of willing may not be (and I hold are not) performed with bodily organs. The capacity or power belongs to the whole agent, not to the agent’s spiritual aspect. So, just as one does not retain a capacity to walk after one loses one’s legs—the act and the capacity belong to the whole human agent—so one does not retain a capacity for conscious sensation or imagination after the complete death of the brain.

Someone holding that the human being is composed of body and soul might object that since in a human being the soul is the formative principle for vegetative operations (breathing, blood circulation, and so on), as well as of sensitive and rational ones, the continuing presence of vegetative operations in brain-dead bodies shows that the soul might still be present, and brain-dead bodies are human beings capable only of those vegetative operations. ⁶

However, while adverting to the human soul, the question that is relevant for determining death is not whether there are any effects that might be attributed to it—as if the human soul were an agent, which it is not—but whether this body, or this portion of matter, is still organized in a way compatible with its continuing to be a member of this kind. For if it is not, then death has occurred. Granted that the human being is composed of body and soul, the soul can be present—inform the matter—only if the matter is proportionate to that sort of soul. In a human being, the matter is disposed to have capacities whose actuation provides (in an environment) conscious sense experience suitable to be data for conceptual thought (and thus also acts of will). Otherwise, although the body might be disposed to constitute a living thing, it will not be disposed to constitute a living thing of the sentient and rational kind. A living being is a thing with a certain nature; and this thing with a certain nature is a thing with a structure that provides it with a capacity for certain types of operations. So, if the organization of the relevant matter is not apt for this whole’s performing, or developing itself to perform, the actions that characterize a given nature, then that whole is not a thing of that nature. With total brain death, the matter (or bodily parts) is no longer organized into a substance capable of participating in a conscious sentient action (and lacks a capacity to develop such a capacity), and so cannot ground a capacity for conscious sentience; so the thing composed of this matter (or these bodily parts) is not a rational animal.

III. THE GENETIC STRUCTURE OF THE BRAIN-DEAD BODY’S CELLS

It might be objected that with total brain death, an individual does not necessarily lose the radical capacity for conscious sensation, because it (or he or she) has the genetic–epigenetic constitution possessed by human beings, and this constitution still provides it with a radical capacity to develop a brain. Alan Shewmon raised this objection to the position Grisez and I have defended. It is possible now, he pointed out, to manipulate adult stem cells to regenerate tissues and parts of organs. And it seems that in the near future it might be possible to manipulate somatic cells to enable an organism to regenerate whole organs, and perhaps eventually a whole new brain (Eberl, 2005, 16).

However, an organism has a radical capacity to perform an action only if it has the structure or constitution such that, given a suitable environment, it can develop itself to the stage where it performs that action—whereas it has an immediately exercisable capacity if it can presently perform that action. A human embryo has the radical capacity for conscious sensation (and for conceptual or rational thought) since it has the capacity to develop to the mature stage of a human being, that is, it has the internal potential, given a suitable environment, to develop a brain and the other structures required for conscious sensation and rational thought. But a (totally) brain-dead individual (not the same as the individual that was alive before brain death) does not have such a capacity. Although it has the genetic–epigenetic constitution within its cells, this is not sufficient for having the active potential to develop to the mature stage of a human being, or to develop a brain. An organism has such an active potential only if its cells are of the right type or structures and they are arranged in a certain way. (The embryo has this internal orientation or disposition, not just in virtue of the genetic-epigenetic constitution of its individual cells; in addition, his or her cells are arranged in such a way that as a unity they have this disposition to actively develop to maturation.) So, while a human embryo has a radical capacity for conscious sensation and rationality, a brain-dead body does not.

Of course, one might manipulate stem cells or somatic cells to restore an organ necessary for a capacity that has been lost. But that possibility indicates only a passive capacity for those cells’ constituents to be used to produce a new structure with a new or restored capacity. A radical capacity for an action or state requires not just that what has the capacity can be used to produce something, but rather that it have an active disposition to develop the structure needed to perform that action or be in that state. Thus, one can use factors in a somatic cell to produce a whole new organism (as in cloning), but that only shows that those factors have the passive capacity to be used to produce new organisms. Likewise, by manipulating the epigenetic states of cells and converting them into other types of cells, one might provide an organism with a new capacity or restore to it a capacity it once had but has now lost. In such instances, the organism is not the agent performing the change, for it does not have within itself the formal or structural specification for the production of that effect. Thus, if factors in the somatic cells of an organism were used to restore to it a capacity to develop a functioning brain, a new capacity would be produced by agents other than the organism whose cells are used, and (since this capacity is necessary for survival or identity of an organism of a certain kind) then the manipulation of the epigenetic state of these cells would generate a new organism.

If the possibility of using the stem cells in a body to produce a functioning brain indicated a radical capacity to develop a brain, it would follow that even a human being who had suffered irreversible cessation of circulatory and respiratory functions would be alive, for a fresh corpse would contain many stem cells that could be used to develop heart tissue or brain tissue, or both.

An entity entirely lacks a capacity for a certain sort of action if it lacks something without which one cannot perform that action under any condition whatsoever, and it lacks the capacity to develop that necessary equipment. Having an optic nerve is essential to seeing in any condition: if one lacks an optic nerve and lacks the capacity to develop one, then one entirely lacks the capacity for vision. And if in the future it becomes possible to develop a new optic nerve and implant it, that will restore the capacity to the same person who lost it, because losing one or another sensory capacity is not the complete loss of the capacity for conscious sensation that results in substantial change of the human being into a lower-level living being (or beings). Likewise, in mammals, including human beings, having brain tissue is necessary for conscious sensation. Thus, if an organism has neither the brain tissue nor the capacity to develop brain tissue, then it entirely lacks the capacity for conscious sensation.

IV. BRAIN STEM DEATH

It has also been objected that if the position defended here were correct, it would follow that the destruction of the brain stem, without destruction of the rest of the brain, would indicate death, and so the view defended here would lead to a looser criterion of death than total brain death. However, in a previous article Grisez and I considered an objection along these lines from Fr. Austriaco (Austriaco, 2009), and we pointed out, referring to an article of Alan Shewmon, that some individuals have conscious awareness after brain stem death when an electrical stimulus is applied near the bottom of the cortex (Machado, 2007, 45–6). Our point was that destruction of the brain stem does not necessarily lead to incapacity for conscious sensation, and so the capacity for rational thought cannot be excluded. However, this point raises a more general puzzle about potentiality. It could be further objected that once a patient’s brain stem becomes destroyed, he then lacks the capacity for conscious sensation because it would require assistance. And so (the argument might run) the fact that conscious sensation can occur with assistance (the electrical stimulus) no more shows that he has the capacity to have sensory awareness than the fact that a brain-dead body could be supplied a brain by the use of his stem cells shows that he is capable of conscious sensation (and would then qualify as a rational animal).

The answer is that an organism that needs assistance in the form of a provision of a prerequisite to its performing a certain action still has the capacity for that action, though its capacity is impeded if that assistance is lacking. The action (or effect) is proportionate to the agent, and the assistance enables the agent to exercise its capacity. Thus, a patient on a ventilator has the capacity to respire, but lacks the capacity (partially, or even entirely) to breathe, needing this assistance. Such a patient has the real internal capacity to respire, though needing assistance in the form of the provision of a prerequisite to that activity to do so. Or a patient might have the capacity to self-nourish—take in nutrients and extract energy and material components from them—but be unable to swallow. He has the capacity to self-nourish but can exercise that capacity only with assistance in taking in the nutrients. A man may have the real capacity to have intercourse but only with the assistance of a pharmaceutical or mechanical aid. And so a person whose conscious sense operation can be activated by administering drugs, raising his or her blood pressure, or providing an electrical stimulus (such things that, obviously, do not involve replacing the dead tissue of the whole brain) has not lost the capacity for conscious sensation but is only prevented from exercising that capacity.

V. SPECIFICALLY HUMAN CAPACITIES AND PERMANENT UNCONSCIOUSNESS

One might also object that the position defended here leads to the conclusion that those who are demented, as for example from Alzheimer’s or severe vascular brain disease, are dead, on the grounds that they have lost the capacity for reasoning and free choice. For I have argued that to be a human being is to have specifically human capacities. And so it might be objected that such brain-injured or diseased patients lack the capacity for reasoning and free choice and so lack specifically human capacities.

However, in the first place, it is in general much more difficult than often assumed to infer the quality of the interior consciousness from external behavior. The absence of rational behavior can be due to problems other than the absence of the capacity for rational thought. The absence of such behavior could instead be due to inability to respond verbally, to emotional deprivation, or to emotional disorders.

Then too, specifically human consciousness or intellection need not be of the kind that is as easily recognizable as reasoning or deliberating about options for choice. The simple awareness of oneself as ‘I’ is a personal act; so, too, is the awareness of another as a you, she, or he, and no doubt such acts can frequently occur without being manifested, much less recognized. Also, it is a common experience for seemingly completely demented individuals to have lucid intervals or flashes of rationality. Thus, from the absence of rational behavior in individuals suffering from Alzheimer’s disease or vascular dementia, one cannot reasonably conclude to the lack of the capacity for rational thought. Even if the individual is not presently rationally aware, as long as this individual has the capacity for consciousness, one cannot exclude the capacity for rational consciousness. And unless the individual has suffered total brain death, one cannot know beyond a reasonable doubt that he or she entirely lacks the capacity for consciousness.

It may also be objected that the position defended here leads to the conclusion that higher brain death, and not just total brain death, is sufficient for death. Fr. Austriaco (2016) has recently argued that the position defended here is disturbing because it might lead to the conclusion that irreversibly comatose individuals and those diagnosed as in an irreversible vegetative state would be dead, given the argument presented above. For, many neurologists hold that the irreversible loss of functioning of the cerebral cortex results in the permanent loss of the capacity for consciousness. If their position is accepted, or if it turns out to be true, it will follow that destruction of the cerebral cortex (as opposed to total brain death) will be a sufficient criterion for death.

In reply, it is true that a human being’s complete loss of specifically human capacities is the passing away of that human being. And since all of the specifically human capacities presuppose the capacity for consciousness, it does follow, given the position defended here, that the complete loss of the capacity for consciousness—including the radical capacity, as well as immediately exercisable capacity for consciousness—is the human being’s passing away. However, the claim that the functioning of the cerebral cortex is necessary for sentience so that its destruction brings about the complete lack of the capacity for consciousness is without foundation. Although this is a widely held assumption, several studies in the last few decades have provided compelling evidence against it. For example, in an article reviewing the neurological evidence, Bjorn Merker points out that empirical studies in animals (mammals) have demonstrated that animals exhibit conscious behavior (orienting, exploration, and a variety of appetitive, consummatory, and defensive behaviors) in response to stimuli of diencephalic and midbrain sites. And, “all of the behavior just mentioned have also been exhibited by experimental animals after their cerebral cortex has been removed surgically, either in adulthood or neonatally” (Merker, 2007, 74). ⁷

The assumption that consciousness has a definite location in the brain or that the brain lacks plasticity is not warranted. Some studies have indicated that conscious states are grounded first of all at the subcortical level. One important study, for example, concluded that, “We suggest that the neural substrate of feeling states [referring to emotions] is to be found first subcortically and then secondarily repeated at the cortical level” (Damasio, Damasio, and Tranei, 2013, 833). ⁸ Instead of being located at a definite part of the brain, the neural substrate of consciousness may arise from the interaction of various parts of the brain. Without wanting to make definite assertions on ethical issues, Bjorn Merker does indicate the clear implication of recent research on sensory awareness and cortical functioning as follows:

Suffice it to say that the evidence surveyed here gives no support for basing a search for such answers [to ethical questions] on the assumption that ‘awareness’ in the primary sense of coherent relatedness of a motivated being to his or her surroundings is an exclusively cortical function and cannot exist without it. (Merker, 2007, 80)

The claim that the position defended here logically implies a “higher-brain death” criterion rather than a whole brain death criterion is mistaken.

Although the loss of all capacity (including radical) for consciousness does indicate the death of a human being, it does not follow that all of those who are completely unconscious and in fact will never regain consciousness are dead. This point is especially important regarding patients who have been in a persistent vegetative state (PVS) for several months. These individuals may still have the radical capacity for consciousness, even though in their particular circumstances they will not actually be helped sufficiently to actualize that capacity. Permanent lack of consciousness is not the same as the complete lack of the capacity for consciousness. Granted, the argument advanced here does not exclude the possibility that someone might have some portion of functioning brain and yet lack the radical capacity for consciousness—and thus have died. However, the question is what criterion should be adopted as a practical matter. And without a certain diagnosis of total brain death, one cannot be reasonably certain that such a capacity does not exist.

There are several reasonable grounds for doubt. First, some who have been diagnosed as being permanently unconscious have regained consciousness. And even on those previously diagnosed as permanently unconscious, various treatments have had some success (though none to the extent of being established as standard care).

Second, it is quite possible that someone who appears to lack consciousness really is conscious but is unable to respond to stimuli. Misdiagnoses of PVS are common. ⁹ Some of the individuals misdiagnosed as being in PVS were conscious but unable to respond. Thus, if someone does not manifest consciousness in response to stimuli, all we are entitled to conclude with certainty is that for some reason they cannot now respond; the reason for that may or may not be unconsciousness. While misdiagnoses do not show that only total brain death actually results in the total lack of capacity for consciousness, nevertheless, they do provide evidence—together with other considerations—that total, and not partial, brain death should be the practical criterion for death.

VI. CONCLUSION

The standard argument for the validity of the total brain death criterion (until the renewed debate prompted by Alan Shewmon’s writings) had two steps: First, the death of a human being is (or results from) the permanent cessation of integrated functioning of the organism; second, the brain’s operation is necessary for that integrated functioning. Alan Shewmon has argued against the second step. It may seem that the argument defended here denies the first step and so radically departs from the standard rationale. However, Grisez and I have not denied the first step but distinguished it. When it is said that a human being’s death consists in “the loss of the integration of the body,” the italicized phrase is ambiguous. ¹⁰ The loss of bodily integration never results in the absence of all integration. When the matter (or bodily parts) that was organized into a human being loses the integration of a human body, it takes on other, lesser integrations. ¹¹ Human death involves the loss of the integration required of a human being. That level of integration is replaced with a lower level. The relevant questions for the criterion of death are: what degree of integration is required of a human being, and is that present after brain death? Grisez and I have argued that because a human being is a particular kind of animal (a rational animal), the integration required of a human being includes the structure necessary for the radical capacity for conscious sensation, which in these bodies would require a brain or the capacity to develop a brain.