I Am Not a Person
There is no person with whom I am identical, though there are persons. I am not Colin McGinn (if “Colin McGinn” names a person). Why do I say that about myself? Why do I say that no one referred to by “I” is identical to a person, though persons exist? Consider a device I shall call “The Person Transformation Machine” (PTM for short). This machine can effect great changes in a person by the mere flick of a switch: it can erase memories, create new memories, alter emotional make-up, intelligence, and preferences, change moral character, generate belief systems—any fact about a person can be changed by PTM. If you step into it (or it steps into you—it might just be a chip inserted into the brain), you come out a different person, literally. People emerge from PTM with completely new personalities, memories, acculturation, emotions, and so on. The whole idea of the machine is to change the person you are, and indeed those who know people who have used it all agree that PTM lives up to its advertising—it really transforms human subjects into new persons. It zaps the old person and installs a fresh one. There is no psychological continuity between the person who goes in and the person who comes out—no preservation of personality traits and other psychological atributes. It is the psychological equivalent of being given a completely new body while disposing of the old one. The original person does not survive the ministrations of PTM.
But the machine also has an interesting conservative element built in: it keeps the subject awake and conscious throughout the personal transformation. The subject can experience the transformation she is undergoing, marveling at what is happening. She can think, “I am feeling queasy” or “I am really enjoying this”. It seems clear that something vital is preserved as PTM does its transformative work: something survives; something stays constant.  The word “I” retains its reference over time. But it is not the person, because that changes. Someone in the machine, awake and conscious, will not feel himself to die as a new person takes root: the prospect of entering the machine is not like the prospect of death. But if something survives and it is not a person, then I am not a person—specifically, I am not that person. I survive the destruction of that person, so I am not identical to any particular person. There are persons, but none of them is me. Then what am I if I am not a person? Here our concepts fail us: what is the concept that specifies the kind of thing I am? The only concepts we can come up with are philosophers’ inventions: ego, self, conscious subject, bare I. Thus we find ourselves saying that the ego or the self or the conscious subject or the bare I is not (identical to) a person. I am an ego or self or subject or bare I and not a person, since I can survive the replacement of the person. But these portentous terms are really just labels for something that remains elusive—the referent of “I”. Evidently something survives transformation in PTM and it is not a person; so we resort to speaking of egos or selves or conscious subjects or the bare I. It is not that this is false or wrong exactly, just unhelpful. We lack a satisfactory sortal for the thing that continues in existence, though something evidently does.
And there is another problem: what exactly is the relationship between the person in question and me? We speak of having a body and brain, but we can’t say that we have a person: my relationship to Colin McGinn (assuming he is a person) is not that I “have” him, whatever that might mean. Nor does he constitute me, since I can survive his disappearance qua conscious subject. The locution that suggests itself is “occupy”: I am occupied by a particular person, and I might later become occupied by a distinct person. I share lodgings with a person, so to speak. But we are not the same thing: Colin and I are numerically distinct. I transcend that person: I stand apart from him, not sharing his fate. It is a familiar thought that a single human life contains a succession of distinct persons, as deep psychological changes occur, but we must not forget that this succession takes place against a background of constancy. The PTM thought experiment dramatizes these kinds of person-altering changes while drawing attention to the invariance of “I”. The thing we call a conscious subject can remain in existence while the thing we call a person perishes—the two have different persistence conditions. I can survive the cessation of the person that now inhabits me, so I cannot be that person.
I may care about the fate of both entities: I don’t want that person to die and I don’t want to die, but these are distinct cares. The same is true of my cares about others. Prudence and altruism thus have a double target: what is good for the person and what is good for the I. We probably care more about the I than the person: I care about Colin McGinn persisting into the future, but I care more about myself persisting into the future. So long as I stay around I can tolerate the extinction of the person who crashes with me. If I were a regular visitor to the PTM, frequently transforming into a new person, I might start to care less about the persons who successively share space with me; but I wouldn’t lose my attachment to the continuing self that oversees all of this replacement. I might relish the variety that comes with personal plurality, while remaining deeply unhappy about the prospect of me being annihilated.
So we must recognize an ontological doubling up, perplexing as it may be: I am something other than a person. I have the attribute of being a person because of my close connection to a particular person, but I am not identical to that person. When I use the word “I” I don’t strictly refer to a person, but to an entity intimately associated with a person—its host, as it were. The person that cohabits with me is like a benign parasite: we are distinct entities with distinct lifecycles, but we occupy the same patch of biological real estate. I play host to that person for the duration (feeding him, etc), and I can pick and choose if I have a PTM handy, but I am not identical to him—any more than I am identical to other parasites that live in my body. The person known as Colin McGinn is a separate being from me, though one with whom I am on intimate terms: he gives me my identity, in the colloquial sense. Without him I would amount to little ontologically, a kind of featureless blob of consciousness persisting over time. Still, we are not to be conflated, he and I. I cannot be reduced to the person Colin McGinn any more than I can be reduced to my body or brain. I am something over and above that person, something of a different order. I am what remains constant in the PTM as different persons come and go—whatever that is exactly. 
 One thing that survives is the brain—it is the same brain before and after the personal transformation. But it would be wrong to assume that the brain is the referent of “I” as opposed to something more psychological. Still, the continued existence of the brain is surely relevant to the question of the continued existence of the referent of “I”.
 For expository purposes I have spoken as if “Colin McGinn” and “I” have different referents, and I think this is intuitively plausible; but there is room for the idea that they refer to the same thing, viz. the transcendent I. If you incline to that position, by all means substitute “the person associated with the name ‘Colin McGinn’”, where this person is not strictly identical to Colin McGinn, i.e. the referent of “I” as I use it.