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Why psychological accounts of personal identity can accept a brain death criterion and biological definition of death

The term “death” can refer to our ceasing to exist … or it can refer to a biological event in the history of an organism. … An organism dies in the biological sense when it loses the capacity for integrated functioning. … But if we are not organisms, this is of little consequence. … What it is important to be able to determine is when we die in the nonbiological sense—that is, when we cease to exist. … We die or cease to exist when we irreversibly lose the capacity for consciousness…. The best criterion for when this happens is a higher-brain criterion.

—Jeff McMahan, “The Metaphysics of Brain Death” [1]

The word “life” may refer to a person’s life or to an organism’s life. Since a human organism exists before it constitutes a person, the life of the organism is not identical to the life of any person. … Persons have first-person perspectives essentially: … We mature persons can think of ourselves from the first-personal point of view; we can reflect on our thoughts—our motives, our desires, our beliefs, our actions…. Hence, a person dies with the irreversible loss of a first-person perspective…. So, medically speaking, there are criteria that distinguish between the death of a person and the death of an organism that constitutes a person—namely, permanent cessation of higher brain function and cessation of all brain function.

—Lynne Rudder Baker, “When Do Persons Begin and End?” [2]

The death of persons, unlike that of bodies, regularly consists in their ceasing to exist. … We have argued, following other personal identity theorists, that a given person ceases to exist with the destruction of whatever processes there are which normally underlie that person’s psychological continuity and connectedness…. These processes are essentially neurological, so that irreversible cessation of upper-brain functioning constitutes the death of that person. Whole-brain death is also death for persons, but only because whole-brain death is partly comprised of upper-brain death.

—Michael Green and Daniel Wikler, “Brain Death and Personal Identity” [3]


Psychological accounts of personal identity claim that the human person is not identical to the human animal. Advocates of such accounts maintain that the definition and criterion of death for a human person should differ from the definition and criterion of death for a human animal. My contention is instead that psychological accounts of personal identity should have human persons dying deaths that are defined biologically, just like the deaths of human animals. Moreover, if brain death is the correct criterion for the death of a human animal, then it is also the correct criterion for the death of a human person. What the nonidentity of persons and animals requires is only that they have distinct criteria for ceasing to exist.

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  1. I am not a defender of any psychological account of personal identity. My own view is what Patrick Toner calls latter-day animalism [4]. Peter van Inwagen [5] and Eric Olson [6, 7] are the most prominent latter-day animalists. The original animalists were Aristotle and Thomas Aquinas. All animalists identify us with human animals. Aristotle and Aquinas work within a hylomorphic metaphysic that characterizes us as essentially rational animals. Van Inwagen and Olson do not insist that human animals are essentially rational as psychological traits are contingent features of human animals. The non-essentiality of the mental is evident in the title of Olson’s seminal work: The Human Animal: Personal Identity without Psychology [6].

  2. It is worth pointing out that the second [2] and third [3] quoted views do not actually support the higher-brain criterion for death, understanding criteria to be necessary and sufficient conditions. Baker’s first-person perspective is roughly the idea of being self-conscious, and that self-consciousness can be lost before the higher brain is destroyed [7, 8]. Green and Wikler believe that we cease to exist with the loss of psychological continuity, but that loss of continuity can occur before thought is extinguished and the higher brain is destroyed [3]. Furthermore, they accept that one can be destroyed by what John Perry calls a “brain zap” [9]. The zap removes one’s psychology but leaves the brain disposed to acquire new memories and beliefs and so does not require the destruction of the higher brain. Thus Baker, Green, and Wikler seem to be providing a defense of the destruction of the higher brain only as a sufficient condition, not as a necessary condition for our death. In fact, Baker probably does not even provide a sufficient condition, given that she argues that we are not animals since we could survive the replacement of our organic parts with inorganic parts that preserve the same beliefs, desires, memories, and other mental functions. Our animal would cease to exist if its living cells were replaced with inorganic, nonliving parts, but our person would persist through those material changes because our mental functioning would continue.

  3. See John Lizza [13] for an overview of other versions of irreversibility—technological, moral, probabilistic, and metaphysical.

  4. See Maureen Condic [14] for the central integrating role of the placenta prior to birth. See Melissa Moschella [15,16,17] along with Joshua Hoffman and Gary Rosenkrantz [18] for the requirement that there be a “master part” doing the integration.

  5. When discussing human beings or human persons in this chapter, I will use body, animal, and organism, interchangeably. So any mention of the person’s animal could be replaced with mention of the person’s organism or the person’s body.

  6. Persistence conditions are, as the term suggests, the conditions that must be met for an entity to continue to exist (persist). An animal with psychological persistence conditions persists as long as it retains certain mental features. An animal with biological persistence conditions persists as long as its life processes continue.

  7. Alfred Whitehead has famously said that the history of European philosophy consists of a series of footnotes to Plato [21, p. 39]. Harold Noonan has claimed that it could be said with even more justice that the history of the philosophy of personal identity consists of a series of footnotes to Locke [22, p. 24].

  8. Peter Geach writes that one could read the identity chapter of Locke’s Essay “like a mail order catalogue,” from which “you buy what suits you” [24, p. 247]. Perhaps he had in mind a Lockean interpretation from the approach that construes persons as modes rather than substances; see Edmund Law [25, pp. 199–200]. This Lockean interpretation does not fit my thesis that persons die biologically: If we are just modes, series of mental events, something like an instantiated program, then we are not material things, flesh and blood, and thus cannot die biological deaths.

  9. As I said above, even if the brain is not the central integrator constitutive of life, my thesis can be adapted to a circulatory/respiratory criterion. For what it is worth, I was personally persuaded over a decade ago by Alan Shewmon that the brain merely regulates an existing integrated organism [12]. But recent work by Moschella [15,16,17] and especially Condic [14] has weakened my support for Shewmon’s critique of brain death. I can be more accurately described as fence sitter on the issue of the correct criterion for death. My confidence is only in the claim that the same criterion for death applies to persons and to the animals that can outlive them.

  10. Bernat has since modified the definition of death to “the permanent cessation of the critical functions of the organism as a whole” [26].

  11. Philosophers are divided about what constitutes the body’s disintegration and thus the end of its existence. So-called terminators [5, 6, 27] believe that the existence-eliminating disintegration occurs when the animal dies and massive chemical changes occur at the microscopic level, despite the fresh corpse appearing similar to the ante-mortem body. The so-called anti-terminators [28,29,30] maintain that the body ceases to exist some time after death, when there is considerable decay and loss of structure.

  12. I use sense, meaning, and definition as synonyms here even though there could be words that have a sense or meaning but not a definition because they express primitive concepts that resist decomposition into any smaller semantic components.

  13. If one thought that biological integration could be lost but there would still be a few moments with just flickers of thoughts, then the person could exist after the death of the organism outside of science fiction and religious scenarios. See Winston Chiong for a brief discussion on the presence of thought post-biological integration [31]. He does not conclude, as advocates of PAPI would, that persons can survive their organisms, only that such organisms are not dead if there is still thought after the loss of bodily integration. I think Chiong is wrong to claim that the organism would survive for a few more seconds, producing thought post-integration. That strikes me as hardly any more plausible than saying that the bird who dies midair is still producing flight until it hits the grounds. However, I do not have the time or space to pursue this matter here.

  14. To avoid further complications with my example, I am assuming that the single cell is not totipotent and so could not give rise to a multicellular organisms.

  15. Leon Kass makes a similar point about fission not being death [33, p. 22]. See also David Shoemaker’s remarks [34].

  16. Van Inwagen makes a similar claim [5, pp. 150–151].

  17. See Rose Hershenov and Derek Doroski for accounts of fetal fusion where a dead embryo is incorporated into its living twin [35]. We may never see a corpse, but there was a death.

  18. The person will also die two deaths in Chiong’s scenario [31], discussed in footnote 13.

  19. While I do not expect that this paper will be abridged and turned into a brochure to be given out to relatives of patients in persistent vegetative states or irreversible comas, nevertheless, it allows PAPI to say that grandma has ceased to do all the things (i.e., instantiate life processes) that the skeptics of higher-brain death insist are constitutive of life.

  20. Recall that I am using body, animal, and organism interchangeably.

  21. The language of pure dualism and compound dualism is borrowed from Olson [39].

  22. So-called survivalist accounts of hylomorphism will reach the same conclusion as compound dualists; see David Hershenov and Rose Hershenov [40, pp. 225–229].

  23. Hud Hudson and Clint Dowland also defend the embodied mind view that persons are found beneath the skin composed of the parts of the central nervous system directly involved in the production of thought [43, 44].

  24. Olson claims that Descartes is read both ways, but more often as a pure dualist [39].

  25. There is a minority Christian tradition that posits the annihilation of some souls in lieu of suffering for an eternity in Hell.


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Thanks to audiences at Georgetown University and the Plato’s Academy, North Tonawanda Campus (PANTC) workshop.

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Hershenov, D.B. Why psychological accounts of personal identity can accept a brain death criterion and biological definition of death. Theor Med Bioeth 40, 403–418 (2019).

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  • Death
  • Brain death
  • Nonexistence
  • Definition
  • Criterion
  • Persons
  • Animals