How Much Brain Do I Need To Be Human?

Some time ago on a hospital ethics committee consult, the patient was an anencephalic child, born in the hospital’s NICU.  The physician had brought the case to the committee and held the view that no symptoms should be treated aggressively. One of the ICU nurses who was caring for this child was surprised that this case came to the ethics committee at all.  In the course of the meeting on this case, she stated her view when she said, “She’s not a person; let her die.”  Though the discussion did not go in the direction of organ donation prior to death, if the issue had been raised, this nurse would likely not have had a problem with that either.

The severely neurologically impaired, such as the anencephalic newborn, the PVS patient and the nursing home resident at the end stages of Alzheimer’s, raise puzzling questions.  They are alive, but do not have much of a life, when it comes to the narrative that distinguishes them from their mere bodily functions.  Our intuitions tend to rebel against the notion that they are human beings like us, because they look and seem to us to be simply bodies that medical technology is sustaining.

These cases raise the question: “How much brain do you need to be human?”  Or to put it more generally: “What kinds of capacities are necessary for one to be considered a person?”  Underlying the former question is another criterion for personhood, that of consciousness/sentience.  With the neurologically impaired, the question we are really asking is: “Can someone be a person without being conscious or sentient?”  The question of brain activity then is related to how much brain activity is necessary to sustain consciousness/sentience, and is actually secondary to the more basic criterion of consciousness/sentience. 

From the first discussions of the criteria for personhood in the 1970s with Fletcher1 and Warren,2 the emphasis was on consciousness and other related capacities, such as rationality, awareness of one’s environment, and capacity for relationships.  These were echoed by Michael Tooley3 and were the basis for James Rachels’ distinction between biographical and biological life.4  They are taken to chillingly consistent conclusions by Peter Singer, who applies them to infanticide as well as abortion and euthanasia.5  Some of the most widely read discussion in this area has come from philosopher/bioethicist Bonnie Steinbock in her book Life Before Birth: The Moral and Legal Status of Fetuses and Embryos.6  She argues that having interests, on which moral status rests, depends on consciousness/sentience.

Some evangelical Christians have also adopted a functional view of a person, based on the image of God7 being more of a function than a status. For example, philosopher Robert Wennberg has concluded that the permanently unconscious patient has lost the image of God and is no longer a person.  Wennberg states, “When an individual becomes permanently unconscious, the person has passed out of existence, even if biological life continues.  There cannot be a person where there is neither the capacity for mental states nor even the potentiality for developing that capacity.”8  Similarly, theologian Robert V. Rakestraw comments, “[T]he spirit of the PVS patient has already returned to God. . . While the body has some kind of residual life, the person is dead. . . The Christian has a theological basis for distinguishing between the death of the body, with its residual movements, and the death of the person.”9

As ethicists within the Judeo-Christian tradition, we should be careful about any view that distinguishes between biological and biographical life.  Biological life, far from being irrelevant to one’s status, actually undergirds the notion of having a life.  It is true that there is a difference between being alive and having a life, but having a life is dependent on how one actualizes his or her capacities, and is irrelevant to one’s value objectively and ontologically. Wennberg and Rakestraw are correct that it is acceptable to remove feeding tubes from the PVS patient, but not on the basis that they are no longer persons or that they have died.  If that were true, then there would be no reason not to harvest their organs, perform experiments on them, or simply perform their funerals and bury them.  The reason we do not bury them is that they are still living persons, even though they have lost the ability to actualize most if not all of their capacities that contribute to having a good life. 

Rejection of an interest view of moral status, or other functional views of a person, would suggest that the PVS patient, or other severely neurologically compromised patients are still persons, and that their standing as persons is not dependent on their neuro-cognitive level of function.  Consciousness/sentience is necessary to the experience of life, but it is not necessary for one to be a person.  The PVS patient, the anencephalic child, the severely demented and the temporarily comatose are all persons with full rights to life, regardless of their level of cognitive function. 

However, it does not follow from this that they must be offered every treatment to keep them alive.  Just because a PVS patient is a person does not mean that the community must do everything, at all time and at all costs, to keep them alive.  Nor does the sanctity of life mandate this. There is a growing consensus, reflected in the Cruzan decision, that medically provided nutrition and hydration are indeed forms of treatment that can be refused, if there is clear evidence that it is the patient’s wish.  In most cases feeding tubes are analogous to ventilator support; removal of feeding tubes is not starving a person any more than removing ventilator support is suffocating them. Further, to insist on a mandatory aggressive treatment based on the sanctity of life doctrine is to elevate earthly life to the status of the ultimate good. If the sanctity of life obligates us to do everything at all times to keep people alive, then we are making a dangerous theological assumption about earthly life being the highest good. From a Christian view of the world, earthly life is a penultimate good; the ultimate good being our eternal fellowship with God. Moreover, with death being a conquered enemy, one thing that follows is that death need not always be resisted. It is acceptable to say “enough,” including the removal of feeding tubes.

The Scripture is clear that a person’s status and rights are grounded in the image of God. This sets human beings apart from animals and provides the essential basis for human dignity. The Bible teaches the continuity of personal identity through time and change. This is the central message of texts like Psalm 139 and Psalm 51, that the psalmist is the same person in the womb and as an adult. Psalm 139 actually extends that notion to the earliest stages of pregnancy, when the unborn child is an “unformed substance,” which some lexicons translate as “embryo.” This is echoed in the Incarnation account. The Messiah is first recognized as coming, not at Jesus’ birth, but at his conception, when He was still in the embryonic stage, in the first few days of Mary’s pregnancy. In philosophical terms, the Bible teaches that we are substances, with an internal, defining, and directing essence—the soul—that remains the same through time and change. That is, we are more than a collection of our parts and properties. Human beings are not “property-things,” but substances. To be sure, souls must have bodies in order to maximize their capacities, even in eternity. But we are not our bodies, any more than we are our brains. We are body-soul unities to be sure, which is the emphasis in the Scripture, especially the OT, where different aspects of a person (heart, soul, etc.) are used as figures of speech for the whole person.10 But this does not mean that human beings are not both body and soul ontologically. 

So how much brain does one need to be human? Enough to be alive. Because to be a living human being is also to be a person. It does not follow that we must do everything to treat persons, especially those in a PVS. But neither consciousness nor sentience nor the ability to reflect the image of God are determinants of what constitutes a person. Those are all functions that are a result of being a person, not the determinants of it. Human beings function in the way we do because we are things of a certain sort—human persons created in God’s image with dignity, moral status and rights to life. 



1 Joseph Fletcher, “Indicators of Humanhood:  A Tentative Profile of Man,” Hastings Center Report 2 (1972): 1-4, and “Four Indicators of Humanhood: The Enquiry Matures,” Hastings Center Report 4 (1974): 4-7.

2 Mary Anne Warren, “On the Moral and Legal Status of Abortion,” The Monist 57:1 (1973):  43-61.  She further refined these views in Moral Status: Obligations to Persons and Other Living Things (New York: Oxford University Press, 1997).

3 Michael Tooley, “Abortion and Infanticide,” Philosophy and Public Affairs 2 (1972): 37-65.

4 James Rachels, The End of Life (New York: Oxford University Press, 1986).

5 Peter Singer, Writings on An Ethical Life (New York: Harper Collins, 2000), Rethinking Life and Death: The Collapse of the Traditional Ethic (New York: St. Martin’s Press, 1994), and Helga Kuhse, ed., Unsanctifying Human Life (Oxford: Blackwell Publishers, 2002). See also the insightful critique of Singer in Gordon Preece, ed. Rethinking Peter Singer: A Christian Critique (Downers Grove. Ill.: InterVarsity Press, 2002).

6 Bonnie Steinbock, Life Before Birth: The Moral and Legal Status of Fetuses and Embryos (New York: Oxford University Press, 1992).

7 The Christian doctrine of humanity created in God’s image is explicitly stated in Genesis 1:26-27; 5:1; 9:6.

8 Robert Wennberg, Terminal Choices: Euthanasia, Suicide and the Right to Die (Grand Rapids: Eerdmans/Paternoster, 1989), 159.

9 Robert V. Rakestraw, “The Persistent Vegetative State and the Withdrawal of Nutrition and Hydration,” in David K. Clark and Robert V. Rakestraw, Readings in Christian Ethics: Volume 2—Issues and Applications (Grand Rapids: Baker Book House, 1996), 128-29.

10 The figure of speech is a synecdoche, of the part for the whole.


This article originally appeared in Ethics & Medicine: An International Journal of Bioethics Volume 24 Issue 3, Fall 2008. Used by permission.

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