I wear corrective lenses because I am near-sighted; I plan on reading a book by Francis Bacon in the near future; last night I had one too many drinks and had a painful collision with a piece of furniture. These are descriptions or stories that say something about the person that I am, but I did not construct these stories; they made me. I will persist as long as these stories are being told by whatever machinery it is that tells them.
   
The first hurdle that we encounter when we start to tackle the problem of how people persist through time is the people themselves. Almost any definition of what a person is that we will be willing to settle on is going to be vague. We can argue back and forth about the qualifications it takes to be a person, but the line we end up drawing will most likely be an arbitrary matter of taste with those meeting the criteria only slightly different than those just under the bar. Deliberately sidestepping this fuzzy area, we may ask, instead, how it is that a being like us persists through time. There are several proposed solutions to this problem that all seem to rest on trying to explain where the numerical identity of a person is located. As I see little reason to believe that the numerical identity of an object is anything more than the projection of that object onto the world by sentient beings, I will take the position that it is the psychology of rational beings that projects people, including our own selves, onto the world, and I will suggest a way that this projection is what constitutes our personal identity.

To get an idea about what solutions have been proposed to uncover the conditions under which a person persists, and to get a better feeling for where our prejudices will be, we can set up four statements about personal identity and decide which of these propositions we are willing to accept. The four statements are as follows:


The reader should note that there need not be a contradiction within these four statements. It would not be entirely absurd to say that all of the four statements are true, or that none of first three are true and the fourth statement is false. In fact, it at least seems that any combination of these statements could, in principle, work, with the exception of the position that rejects the first three criteria and accepts the fourth proposition as true. We should also be aware that, different from saying that a certain type of continuity is sufficient, we may want to claim that certain types of continuity are necessary for personal identity. For instance, if we believe that the first and fourth statements presented are true, and that the second and third are false, we would conclude that bodily continuity is not merely sufficient, but necessary for continued personal identity. In a similar manner, we may also decide that both psychological and bodily continuity are necessary for personal identity, and a person would be unable to persist unless both of these attributes were present. Thus we find ourselves with several possible answers to the question of what exactly is doing the persisting in beings such as ourselves, and although there may be some interesting examples to the contrary, when push comes to shove, the psychological functions of a person will triumph over the whole of an individual's properties.

For the purpose of everyday discussion, we at least have a strong reason to believe that what is persisting for an individual is the person's psychology. At least, if we were to speculate on a situation in which the body and the psychology of a person became separated, few of us would want to claim the individual existed in the body. To illustrate this with a thought experiment, we may imagine that a brilliant neuroscientist, Patricia, has crafted a computer chip that will store all of the contents of her psychology. She has the chip inserted into her own skull and the device neatly keeps tabs on all of the functions that her organic brain naturally performs. So quick and accurate is the device, that at any time it would be fully capable in and of itself to carry on all of the neural processes of Patricia. The device comes in handy, as soon after the chip is inserted, Patricia suffers a severe blow to the head in a car accident, and her brain tissue becomes irrevocably damaged. Prepared for such an event, Patricia's husband inserts the chip, which has survived intact, into some sort of organic machine which receives and distributes commands from the spared computer chip in precisely the same manner as human neurological components would normally do. The stunned machine comes to and notices, on some sort of operating table, the corpse from which the chip has been retrieved. In a manner indistinguishable from our brilliant neuroscientist, the machine asks what has happened.

What we believe to be the reaction of Patricia's husband, or widower, will reveal a great deal about our projections of personal identity, and I find these reactions to be hardly debatable. Putting ourselves in the shoes of the man who has performed this bizarre operation, could we really imagine answering such a question by telling the story of a partner who has suffered a horrible accident and is now lying motionless on the operating table. Our answer would almost surely be more along the lines of “you got into an accident, your body can no longer be used.” The reader should note that this example is merely to show that our projection of psychology takes precedence over viewing the individual from the bodily perspective, and the thought experiment at least shows that psychological continuity alone is sufficient for establishing how we view personal identity, but I am actually willing to go much further. The organic machine is not deceiving Patricia's husband. Patricia is not lying on operating table, nor is she a soul in some sort of different realm; she is as much present as she was before the operation as an entity inside the organic machine. The projection of Patricia as a single agent is what makes her survive as a person. This is not the projection of her husband, but of whatever machinery it is that projects itself as Patricia.

Before continuing, some philosophers will insist that there is a problem in this picture that has not been addressed. It seems that, whether at the time of Patricia's accident, or the time of the machine's awakening, a being that was once Patricia has turned, instantaneously, into a corpse. This argument should not bother us if we are to take an eliminitivist standpoint. Certainly there is no actual overhaul of physical constitution taking place, and the problem of such a transformation seems much less of an issue if we are content in saying that our own projection of Patricia onto the world has been altered. This is not a special circumstance at all, but is fairly routine for beings such as ourselves. When a compact disc that I own becomes defective, it changes into a Frisbee or a coaster in no less time than Patricia's transformation into a corpse, and no physical changes internal to Patricia need to take place to account for this. Indeed, we shall soon see why a projection of our brilliant neuroscientist as a single agent is exactly what makes up Patricia's personal identity.

The idea of a unified self is such an overpowering intuition that scientists and philosophers throughout history have searched long and hard for some sort of Cartesian Theater where everything comes together in the brain. Descartes was convinced that the pineal gland was the place in which information was moved from the material brain to the immaterial mind; the gland “is the only organ in the brain that is in the midline, rather than paired” (Dennett 104). Although scientists now seem to agree that “there is no such single point in the brain” where everything comes together, we are left with the problem of how to explain the illusion of a unified self (Dennet 257). Observing the functions of the human brain and concluding that no such Cartesian Theater seems to exist is a step up in neurology, but this conclusion should hardly leave us satisfied. To deny that I have a powerful experience of a unified self would be an outright lie; the phenomenon demands some sort of explanation.

It is important to note, as a starting point, that any evolved organism must be able to correctly distinguish between itself and the rest of the world. In a “blind, unknowing way,” even amoebas are forced to make this distinction to avoid eating themselves, and to direct repair and protection onto themselves, and not anything else (Dennett 414). An interesting exception to this rule may exist when we consider eusocial organisms such as ants or termites, but this is a digression I will not delve into now. What is important is that any biological organism, including ourselves, can be expected to possess a deep-seated mechanism for distinguishing itself from the rest of the world. Like less complicated organisms, apes such as ourselves will fight off incoming pathogens that the body does not recognize, but cognitively, we must also be able to distinguish between things that are happening, or have happened, to us as opposed to other beings. The need for such discriminating tabs on events is especially true for social animals such as humans. For example, after eating my mother's cooking last week, everyone else felt fine, but I got very ill, so it may be best to avoid my mother's cooking in the future. It is vital for me to recognize myself as a single agent for other reasons as well. If the fingers typing this sentence are not recognized by the brain giving them instructions, then something beyond the boundaries of this organism must be causing them to move as they are, but the brain recognizes the fingers as 'my' fingers and the thoughts as 'my' thoughts; both are seen as internal, and not part of the rest of the world. To put it differently, every animal must have a mental model of the world to respond to, and what could be “more crucial than the model the agent has of itself? (Dennet 427). All of the thoughts, intentions, and sensations that occur in various areas of the brain are projected as being a part of this organism, and not the rest of the world; these thoughts belong to 'me,' or, better yet, these are 'my' thoughts. Dennet describes this phenomenon as “center of narrative gravity,” which is roughly analogous to the physicist's use of center of gravity (Dennet 418). Like a physical center of gravity, a narrative center of gravity, a self, is equally real, but not a physical part of the brain.

For most human beings who have been around for some time, the narrative center of gravity is shrouded in further complexities by memes. A rough definition of what a meme is would be a “unit of cultural inheritence” (Dawkins 297). This definition, however, may mislead, and perhaps memes would be better stated as “the sort of complex ideas that form themselves into distinct memorable units” (Dennett 201). Instructions for making a paper airplane are memes, and those instructions that survive poorly in their environment are unlikely to be passed on. We can see that, like their genetic counterparts, memes also may undergo a Darwinian evolution; the memes that replicate themselves most efficiently become the most prominent in their environment, the brain. Susan Blackmore, author of The Meme Machine, suggests that “memes can gain an advantage by becoming associated with a person's self concept” (232). We can at least see how competing ideas give us new ways to separate ourselves from the rest of the world. I believe that consuming animal products is morally wrong; my roommate does not share this sentiment. The meme in question finds a niche influencing my center of narrative gravity; the memes occupying my brain, just like the memories and perceptions, are projected to a single unified agent.

In conclusion, my personal identity is not a material part of the world occupying a region in space, but this does not mean that I am any sort of immaterial substance. What I am is a projection that has been constructed to present a unified agent that separates 'me' from the rest of the world. As a result, unlike the psychological view presented by Shoemaker that rejects the possibility of “any brain-state transfer procedure,” there is no reason for me to believe that I am in any way bound to a particular physical medium such as my body or brain (Shoemaker 530). As long as such projections of me are being made, my personal identity is capable of surviving a transmission onto some sort of computer chip in the same way as Patricia's has in our earlier thought experiment. More astounding yet, I may be transmitted just as readily as computer games, movies, or any other type of software we can imagine. I may be stored or duplicated, and I will survive inputs or deletions of information in the same way that I am currently making and losing memories. What is important is not the physical medium but the projection of a single unified agent that is my center of narrative gravity.


Blackmore, Susan. The Meme Machine. Oxford: Oxford UP, 1999.

Dawkins, Richard. The Extended Phenotype. 2nd ed. Oxford: Oxford UP, 1999.

Dennett, Daniel C. Consciousness Explained. 1st ed. Boston: Little, Brown and Company, 1991. 101-430.

Larkin, William S. Lecture. Southern Illinois University Edwardsville, Illinois. 29 Mar. 2006.

Shoemaker, Sydney. "Functionalism and Personal Identity—a Reply." Nous 38 (2004): 525-533. Academic Search Premier. EBSCO. SIUE, Edwardsville. 16 Apr. 2006.