The terms “existence” and “permanent non-existence” convey in a more precise fashion what is usually conveyed by the predicates “alive” and “dead” and their derivates. When used non-metaphorically, “alive” is a predicate that conveys the information that an entity of a certain kind has not permanently ceased to exist. The entity in question is a living being. Inasmuch as I have no doubt that I exist, I should have no doubt that I am a living being. Essentially, I am an embodied mind that is generated by my brain. Once I was a pre-personal living human being without a first-person perspective and I might end up as a post-personal human being. I cease to exist permanently when my brain permanently ceases to generate consciousness. For a living being to have ceased to exist forever is to be dead. What remains after a living being has died is not a dead body but the body of a living being that has ceased to exist forever. If a functioning organism remains after I have ceased to exist forever (as in the brain-death constellation), this organism would not constitute a living being. It would be the functioning organism that formerly constituted myself, the living being. Before I came into existence there was a functioning organism that later constituted myself and became my organism. Organisms that constitute living beings are alive only derivatively. This amounts to a mentalistic definition of “living being”, “end of a life”, “beginning of a life”.
A definition of life
What does it take to achieve a non-arbitrary definition of the terms “living being”, “death” and “beginning of a life”? A chapter in revisionary ontology
1. We should be able to agree on at least one specimen/example for the term “living being”.
There is some dispute on the question of whether or not viruses should count as living beings. There is less dispute as regards plants. There seems to be no dispute at all with respect to people, such as you and me, author and reader of these lines. At least you and I are living beings. This assertion is more than an intuition; it is a condition for meaningful description with respect to our place in the physical and social world.
2. We should be able to agree on the assumption that “death” is a term that refers to the permanent end of the existence of a living being.
We should rule out metaphorical usage of the term “death”. Many things irreversibly pass out of existence. Some people use the term “death” to refer to the irreversible existence of entities other than living beings, such as “sun” or “flame”. If we do not restrict ourselves to non-metaphorical usage of the term “death”, all aspirations of coming to grips with a definition are in vain.
3. We should be able to determine what a living being is essentially. In order to do so we will have to ask: which is the property I or you cannot lose without irreversibly ceasing to exist? If we know what a living being is essentially, we can determine what living beings, in general, are essentially.
These lines were written or are being read by a living being that is a person, as the content of these lines is accessible only to beings that are self-aware. Are we essentially persons and do we cease to exist irreversibly when we lose the qualities or abilities usually ascribed to persons? There is a standard test, the Avoidance of Future Great Pain Test, that may elicit an answer: would you, named XY, as a self-interested rational person, invest today financial means in order to prevent substantial pain that an Alzheimer’s patient, named XY, with a brain in decay will suffer inevitably in years to come if you do not invest those means today? The question is meant to elicit an answer to the question: would that patient, who doesn’t even remember his name or recognize his relatives, be you or someone else? Is it you who continues to exist although Alzheimer’s has eradicated all memories; or is it someone else who came into existence as all memory vanished? Depending on whether or not you assume that you are identical with Alzheimer’s patient XY in, say, 11 years, you will or will not invest (provided you act today as a self-interested actor). I, for one, would invest since I am convinced that the pain would be felt by me who would continue to exist as a post-personal being – even though I would not know who I am. If I were XY, I would invest because I am convinced that I would persist through the loss of personhood.
To many, Avoidance of Future Great Pain Tests reveal that I am not essentially a person. This conclusion is supported if I look backwards: I did not come into existence as a person but developed personhood gradually. Before I became a person, I was a sentient foetus that eventually was born as a sentient baby. Hence, I understand “person” as a phase sortal.
Therefore, generally speaking, what I am essentially seems to be a mind that is supported by specifically organised matter without which it couldn’t exist. I am an embodied mind. If I am a living being and if what I am essentially is an embodied mind, then any entity that essentially is like me counts as a living being.
4. Once we know what living beings are essentially, we will be able to determine when they cease to exist forever.
If I am essentially an embodied mind, I may lose the first-person perspective and continue to exist. Likewise, as an embodied mind, I might even lose 97% of my body – I presumably wouldn’t cease to exist as long as those 3% of my body that are essential in order to generate my mind persist and function properly. A living being ceases to exist forever when the bodily presuppositions of a mind irreversibly cease to be given.
5. Once we know when a living being ceases to exist forever, we will be able to determine when the existence of a living being begins.
If I cease to exist forever when my brain ceases to generate consciousness forever, then, symmetrically, I began to exist when my brain supported consciousness for the first time. Generally speaking: a new living being comes into existence when an organism or a brain or other material processes generate consciousness.
6. These tasks fulfilled, we should be able to give a definition of the term “living being”.
I, as a living being, began to exist when my brain generated consciousness for the first time. I will have ceased to exist forever (in common language: I will “be dead”) when my brain has permanently ceased to generate consciousness (note: my brain might permanently have ceased to generate consciousness without, under certain conditions, having irreversibly ceased to generate consciousness. One might reasonably say that my brain retains the capacity to generate consciousness when deep frozen. However, if I am in a deep frozen condition on board a space ship that went out of control, the people on earth will say that I died when my brain permanently ceased to generate consciousness even though it might retain a capacity to do so). This allows for reversible non-existence: if my brain intermittently generates no consciousness at all (as perhaps in a deep sleep or coma or deep-frozen condition), then I would intermittently not exist . I would intermittently not exist without being intermittently dead; as “death” refers to permanent non-existence. The span of my existence, my lifespan, is tantamount to the time during which my brain generates consciousness. As other minds might not be generated by brains, but by other organs or even by the organism as a whole (as is perhaps the case with unicellular organisms) or by electronic systems, a definition of living being will amount to: a living being is a mind that is being generated by properly organised matter.
If the intension of the term “living being” can be formulated as “an embodied mind” or “a mind that is generated by processing matter”, then the extension of the term “living being” includes all entities that are embodied minds.
7. Although we have been able to offer an apparently non-arbitrary definition of the term “living being”, we still have to agree on the following: we should rule out the acceptability of two or more definitions side by side. A definition is a definition by virtue of its comprising all entities a certain term is referring to. Where there are two or more definitions for one and the same term – two different intensions with two different extensions – the task of defining the term has not been carried out properly.
Versions of an embodied-mind account of our survival/of identity and, by the same token, of the existence of living beings are defended by quite a few philosophers, and it seems more popular than organismic accounts of identity. To my knowledge, however, all of these philosophers juxtapose and resort to two definitions of the term “living being”. For them, the intension of the term “living being” is twofold. First and foremost, they regard all embodied minds as living beings, an implication of which is: I am a living being. On the other hand, they view all functioning – though mindless – organisms as living beings, an implication of which is: before I began to exist/to live, the functioning organism – that later became my body – was a living being. However, this fails to adequately come to grips with a definition of the term “living being”. There is a first definition of the term living being: every entity that is an embodied mind is a living being. And there is a second definition of the term living being: every entity that is a functioning organism is a living being.
Proponents of the embodied-mind account of identity/survival tend to juxtapose two definitions of the term “living being” because they are at a loss when it comes to the ontology of what we may call pure – that is: mindless – functioning organisms. In the embodied-mind account of living beings, there was a pure organism before I came into existence, before my life began. Symmetrically – as is the case with brain-death – there might be a functioning pure organism after I have irreversibly ceased to exist. Some proponents of an embodied-mind account of identity endorse that the latter pure organism is a living being although I have ceased to exist forever.
After what has been outlined above, however, a pure organism should not count as a living being, since we found that living beings are entities, which is what you and I most fundamentally are. Most fundamentally, you and I, who doubtlessly are living beings, are embodied minds, but not pure organisms. If this is the case, then pure organisms must be ruled out from the extension of the term “living being”.
8. We will have to face the consequences of the mentalistic definition of the term “living being” and of the end and the beginning of a life
Some will have difficulties in accepting the consequences of this supposedly non-arbitrary definition of the term “living being” because its philosophical implications contravene some of our bedrock intuitions: if pure organisms do not count as living beings, then it would be inappropriate to talk about the life, death and killing of plants, early embryos and of the functioning bodies of the deceased, i.e. the brain-dead. The question is: should our intuitions override our arguments? A good case in point is the definition of the term “planet” that was endorsed by the International Astronomers’ Union in 2006. The intension of the actual definition of the term “planet” is such that Pluto does not belong to the extension of the term whereupon it lost its former status as a planet.
My mentalistic definition of the terms “living being”, “end of a life” and “beginning of a life” can be used to answer a looming question that haunts those who assume there is a living organism before I begin to exist and after I have died in a brain-death constellation: were there two living beings, myself as a living being, and my functioning organism as a second living being? A powerful philosophical tool to address this riddle is the Constitution View, a main proponent of which is Lynn Baker. According to Baker’s account of the Constitution View, you and I are essentially persons (beings with a first-person-perspective) that are being constituted by our living organisms. As she explains, my organism is a person only derivatively, while I am a person essentially. Hence, I cease to exist forever when I cease to exist as a person. According to Baker, I am dead when I cease to exist as a person. And if I go into an irreversible coma, what remains is a living organism that had previously constituted myself, the living person. When this happens, Baker explains, the living organism is “precipitated out”. The metaphysics of this “precipitating out” seems unfathomable and would need further explanation in order to become convincing. Despite this, the idea of the constitution-relation proves helpful: in my account I am constituted by a body, a functioning organism (or, more precisely, by a brain that functions sufficiently). In opposition to Baker and proponents of other versions of the embodied-mind account of identity, I claim that what remains when I irreversibly cease to exist in a brain-death constellation is not a living organism. Rather, it is the functioning organism that (or: whose brain) constituted me. I was the living being. The organism (the brain as long as it generated consciousness) constituted me, the living being. Doing so, the organism was a living being (an embodied mind) only derivatively, while I was an embodied mind (a living being) essentially. Even though functioning organisms constitute living beings, they are essentially not.
Akerma, Karim: 2006, Lebensende und Lebensbeginn. Philosophische Implikationen und mentalistische Begründung des Hirn-Todeskriteriums, Lit Verlag, Hamburg
Baker, Lynne Rudder: 2000, Persons and Bodies. A Constitutional View, Cambridge University Press
Benatar, David: 2006, Better Never to have been. The Harm of Coming into Existence, Oxford University Press
Ford, Norman: 1988, When Did I Begin?, Cambridge University Press, Cambridge
Gervais, Karen Grandstrand: 1986, Redefining Death, Yale University Press, New Haven and London
Green, Michael B./Wikler, Daniel: 1980, Brain Death and Personal Identity, in: Philosophy & Public Affairs 1980, 9, no. 2, pp. 105-133
Liao, S. M.: 2006, The Organism View Defended, in: The Monist 2006; 89 (3), pp. 334-350
Lizza, John P.: 2006, Persons, Humanity, and the Definition of Death, The John Hopkins University Press, Baltimore
Lockwood, Michael: 1985, When does a Life Begin?, in: M. Lockwood (ed.): Moral Dilemmas in Modern Medicine. Oxford University Press 1985, pp. 9-31
McMahan, Jeff: 2002, The Ethics of Killing. Problems at the Margins of Life, Oxford University Press
Olson, Eric T.: 1997, The Human Animal. Personal Identity Without Psychology, Oxford University Press, New York-Oxford
Unger, Peter: 1990, Identity, Consciousness & Value, Oxford University Press 1990
Unger, Peter: 2000, The Survival of the Sentient, in: Noûs, Volume 34, Supplement 4, October 2000 , p. 325-348
Zinkernagel, Peter: 1962, Conditions for Description, Humanities Press, New York
 For an analysis of conditions for description cf. Zinkernagel (1962)
 Cf. Unger (1990, 27ff and 2000).
 At this point it may be justified to substitute the common expression “the embodied mind account of survival/identity” by “the embodied-mind account of living beings”. The embodied-mind account of survival/identity is always aimed at as an account of the conditions of the survival of a living being. Therefore, my alteration seems justifiable.
 Among them are Green/Wikler (1980, 107), Lockwood (1985, 11), Gervais (1986, 2), Unger (1990, 7), Baker (2000, 18f), McMahan (2002, 4), Lizza (2006, 13). According to organismic accounts of identity a living being is most fundamentally a functioning organism. This account of identity is held, among others, by Ford, Olson and Liao. Benatar’s account of our survival/identity is ambivalent: “… each one of us was once a zygote…” (2006, 134), but as a zygote we did not yet exist in a morally relevant sense. According to Benatar, a living being comes into existence in a morally relevant sense when an organism, being conscious, has interests (cf. l.c. 133ff).
 Lizza calls it “a ‘humanoid’ or ‘biological artifact,’… a form of life created by medical technology.” (2006, 15)
 “A ‘planet’ is a celestial body that (a)is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit.” (http://www.iau.org/public_press/news/release/iau0603/) Viewed 2009-03-01, 14:56 GMT
 Some people even took to the street in order to voice their discontent with the newly established definition and Pluto’s ensuing loss of planethood (cf. New Scientist, 21 January 2009).
 There is an asymmetry in her account since she claims that I existed well before I displayed the abilities typical for a person. Baker would parry this reproach saying that I have always been a person; already as a newborn I allegedly was a person because I evolved towards a person. By comparison, an ape, whose cognitive capacities are paramount to mine when a baby, is not a person on her account.
 “Although a human person has a single life that incorporates organic life, it is metaphysically possible to »precipitate out« an organic life that is not personal…” (Baker, 19)
 According to the Constitution View as defended by Baker, “if my mother had miscarried when she was five months pregnant with the fetus that came to constitute me, I would never have existed.” (Baker, 204) At the same time she claims that, most fundamentally, I am a person and that, because of the potentiality, persons exist as such even before first-person perspective is achieved: “To be a person… one must have the capacity for a first-person perspective.” (Baker, 92) And: “… a normal newborn human is (i.e., constitutes ) a person.” (l.c.) Furthermore: “So, from birth, development of a first-person perspective is underway” (l.c., note). Here, we are at a loss as regards the question whether or not we existed when the five-months-old sentient fetus existed. On one occasion Baker claims it wasn’t me. At the same time, however, she has it that the mere capacity for a first-person perspective is sufficient for there to be a person. Baker’s general problem is with the ontology of living beings that are neither pure organisms nor persons.