Yet of course when I say “I” I do not just mean this present experience. With “I” I mean something that can have experiences other than just the presently experienced one and which actually has different experiences from moment to moment. Hence, there is obviously a certain transcendence of the “I” with regard to individual experiences. There are not simply successive experiences, each with its own “mineness” (first-personal givenness), but rather it is I who has this experience now and that experience then. And based on this, I have a clear intuition of what it means for some future or past experience to be experienced by me.—Yet, what does it mean? What is it that remains the same throughout all the changing experiences? A state of consciousness now and a state of consciousness in some more or less distant future are evidently different states of consciousness. What makes them states of the “same” consciousness, and what is the nature of this “sameness” (i.e. the nature of the transtemporal identity of the experiencing “I”)?

A denier of a distinct “ego” or “self” does not have to claim that the different experiences have nothing at all to do with each other. She can of course acknowledge that the experiences of one stream of consciousness are strongly connected to one another in a way that they are never connected to experiences of other streams. She only has to reject the assumption that they are connected through being experienced by one and the same subject and instead claim that the oneness of “one subjectivity” consists in the connectedness of the experiences.Footnote 10 There is no denying that in their streaming, experiences integrate themselves into one stream of consciousness. But that is about it. The transtemporal unity of consciousness is a result of a self-unification of experiences and not due to an enduring “I”. So, in this view, what we call the “identity” of our self consists in certain relations between “our” experiences that bind them together (relations of memory, continuing intentions and character traits, etc.). “My” experiences are not united by having a common relationship to the same “I” (me), but simply by certain relations that hold between them. Hence, there is something like “one subjectivity” to which the single experiences belong, but this is no “owner” of its experiences but rather (in one way or another) constituted by the experiences and their interrelations. This amounts to what Derek Parfit calls (and espouses as) the “reductionist” view of personal identity.Footnote 11 “Reductionism” here refers to the thesis that the subject’s identity consists in something else (something more fundamental)—namely certain inter-experiential relations (or also relations of experiences to one and the same body)—to which it is therefore reducible. It stands opposed to substantialist (Cartesian) views that hold that the identity of the self does not consist in anything else, but literally means the remaining-the-same of the ego who has the experiences.—Today, this latter position is clearly in the minority,Footnote 12 while the debate about “personal identity” is mainly concerned with the question of which particular relations personal identity consists in, thereby presupposing the validity of the basic reductionist claim.

Returning now to the phenomenological account that sees the origin of the mineness of experience in its first-personal mode of givenness, where is it to be positioned within this opposition of relationism/reductionism and substantialism/non-reductionism?—This account holds that the origin of what is meant by experiences being mine does not lie in their belonging to an “I” that would be in some way distinct from the experiences, but in their givenness in a first-personal way, “as mine”. When experiences elapse into the past, in no way do they simply vanish into phenomenal nothingness; and this elapsing also does not mean a total estrangement: They continue to be accessible “as mine”, “from the inside”, as it were. A past experience can be first-personally given no less than a current experience, and there is no further act of identification involved, any more than there is with a current experience (I would never ask “I remember a past experience, but whose was it?”—no “error of misidentification” is possible hereFootnote 13). So the mode of givenness of my experiences is clearly distinct from that of the experiences of others, temporal distance notwithstanding.

But the crucial question is: Are my experiences given in a different way than others’ because they are mine, or are they mine only insofar as and because they are given that way? That is to say: Are past experiences only mine by virtue of being given in my present experience “as mine” (first-personally)? After all, a past experience is given first-personally not only to my present experience, but was also, and primarily, thus given to itself when it was present—what is the relation of these “minenesses”? Is the “sameness” of mineness constituted by retaining the past mineness in my present mineness? Is the past experience, in its present givenness as mine, revealed as having been mine, or does its mineness mean nothing other than that it is now given that way? The latter view again amounts to a reductionist account of the identity of the self, since then this identity is constituted by a certain relatedness of experiences.Footnote 14

The view that the oneness of “one mind” means that various experiences are unified, and that this unification is due to some inter-experiential relations is certainly not utterly implausible. On the contrary, as a matter of fact, prima facie, it seems to be nearly self-evident—how could it be otherwise? Yet on closer inspection, as the debate about personal identity brought to light, it turns out to have highly counter-intuitive implications.

These implications are due to the fact that concepts like “connectedness” or “continuity” allow for degrees and also, at least in principle, for splitting and merging—conceptual possibilities that are quite incompatible with our intuition of what it means for a future or past experience to be mine.Footnote 15 Experiences can be more or less unified, borderline cases are possible where only an arbitrary decision can determine whether something should or should not count as belonging to a unit of bound-together items. But can experiences be more or less mine? Can there be borderline cases of mineness? Is it not necessarily the case that each experience is either experienced by me or not, without any in-between? And is not the question of whether it is the one or the other a real difference and not just a question of referring to the same matter of fact in different ways?

In my view, one of Parfit’s strengths is the clarity with which he works out the counter-intuitive consequences of his reductionist view and embraces them, dismissing our everyday intuitions as erroneous. This is the way he employs, for example, his notorious “teletransportation” thought-experimentsFootnote 16: Teletransportation means a fictitious future way of travelling by dissolving my body here (say, on Earth) and instantly replicating it—including every detail of my brain structure and thereby, assumedly, all of my psychological traits and memories—somewhere else (e.g. on Mars). My replica is clearly aware of having been on Earth a moment ago and has all the character traits, plans etc. I had: According to any psychological criterion of personal identity he is me. Now Parfit tells a story of a victim of device malfunction: He gets replicated on Mars, but still remains undissolved on Earth. He is deeply shocked: the person on Mars is not him; he is just someone like him who believes himself to be him. But he is the person here on Earth. So it seems that even if the teletransportation device had functioned in the usual way, this replica would not have been him either. And he would have been killed.

However, Parfit insists that this shock would be irrational: For, if there is not something like a spiritual “ego”-entity (which we simply have no reason to believe in), what we fear might not happen in teletransportation—namely the transportation of my “I”—never happens at all.Footnote 17 My survival from moment to moment never involved more than the future existence of experiences which stand in the right relation to former experiences. There has never been anything like a surviving “I” (or, if you will, the survival of my “I” (of me) consists in these relations).

So “what matters” with regard to my survival, according to Parfit, is the future existence of experiences that stand in the right relation to my present ones. If there would be—e.g. in the imagined duplication case—several persons whose experiences meet this condition: so much the better. Double survival cannot be equated with death. If one of the two persons would lead a happy and fulfilled life and the other would suffer miserably, there would be no point in hoping to be the one and not the other: The question “Who of these persons will be me?” is simply meaningless—for there is no “I” that could be either of them.Footnote 18

Yet this is quite hard to accommodate with our intuition of what it means for an experience to be mine. The logical possibility of duplication forces upon us the intuition that there must be more to being me than merely some continuity-relations between experiences—there must be some “extra-ingredient” that makes experiences mine. “From the point of view of the person himself”, as Thomas Nagel observes, “the question of his identity or nonidentity with someone undergoing some experience in the future appears to have a content that cannot be exhausted by any account of memory, similarity of character, or physical continuity.”Footnote 19

Not only does it seem thinkable that experiences that are sufficiently continuous with my present ones are nonetheless not mine, but also that future experiences which are not thus related to my present experiencing are nevertheless mine. This becomes evident when one considers—along the lines of a famous thought-experiment by Bernard WilliamsFootnote 20—that the prospect of being tortured would lose nothing of its horror if the prospect of suffering complete amnesia and a profound change of character beforehand would be added: this would not convince me that I have no reason to fear the torture (i.e., it would be of little comfort if a reductionist assured me that, per definition, the person in pain will not be me), rather, I would be even more dismayed, because not only would torture await me, but also total mental derangement. This does not really make the prospect more pleasant. As Geoffrey Madell rightly observed, what I am afraid of is not that there will be pain accompanied by memories of my present experiences, but simply that it will be me who will be in pain—and it does not seem that both mean the same thing.Footnote 21 So obviously, with the “mineness” of future or past experiences we mean something that is irreducible to any connectednesses between experiences. It appears that no rupture in the stream of consciousness could rule out a priori some future experience being mine.—But if it is conceivable that I might have experiences that are completely divorced from my present ones—what is it then that makes them mine? If there is a clear difference between a future person no longer being me and his being me but profoundly changed (to whatever extent)—in what does this difference consist?

While one could be tempted to dismiss the duplication scenario as being totally fictitious (although split-brain cases might suggest otherwise), the amnesia case is not that far-fetched. One can, for example, imagine suffering from Alzheimer’s disease and anxiously wonder what it will be like in its final, highly dissociated stages—and whether the sufferer will really still be oneself. For Parfit, this would be what he calls an “empty question”,Footnote 22 and he would reply that you could call it this or that, but that this does not designate any real difference. Yet of course such an answer would be highly unsatisfactory: One can hardly avoid being convinced that any future experience is either mine or not mine, and that this is not a question of arbitrary definition or convention—and that it makes even less sense to say that it is partly mine, partly someone else’s.Footnote 23