closest continuer, closest predecessor and the quandary of overlap situations

robert nozick'in "en yakın takipçi" kuramını sunar: [ardından da düşüncenin tartışmasını içeren düşünce deneylerini özetledim efem]

personal identity through time, robert nozick; in personal identity; ed by raymond martin and john barresi, blackwell publishing, 2005 p92. (from: Robert Nozick, "Personal Identity through Time" pp.48,50-1,58-61, and 69. Cambridge, Mass.: The Belknap Press, imprint Of Harvard University Press, 1981.)

To be something later is to be its closest continuer.

The closest continuer view helps to sort out and structure the issues; it does not, by itself, answer the question. For it does not, by itself, tell which dimension or weighted sum of dimensions determines closeness rather, it is a schema into which such details can be filled.
The nature and contours of people's responses to the puzzle of the ship fits the closest continuer schema and supports it, if not as a metaphysical truth then at least as a component of a psychological explanation of these responses.

The closest continuer view presents a necessary condition for identity; something at t2 is not the same entity as x at t1 if it is not x's closest continuer. And "closest" means closer than all others; if two things at t2 lie in closeness to x at t1, then neither is the same entity as x. However, something may be the closest continuer of x without being close enough to it to be x. How close something must be to x to be x, it appears, depends on the kind of entity x is, as do the dimensions along which closeness is measured.

If persons conceivably can transfer from one body to another, still, bodily continuity can be an important component of identity, even (in some cases) its sole determinant. The dimension of bodily continuity can receive significant weight in the overall measure of closeness for persons.
To say that something is a continuer of x is not merely to say its properties are qualitatively the same as x's, or resemble them. Rather it is to say they grow out of x's properties, are causally produced by them, are to be explained by x's earlier having had its properties, and so forth.

[not sameness but a kind of continuity: ]

This causal dependence, however, need not involve temporal continuity. Imagine that each and every thing flickers in and out of existence every other instant, its history replete with temporal gaps. (Compare how messages are transmitted on telephone wires.) According to concepts developed later in this chapter, if every thing leads this mode of existence, then it is the best kind of continuity there actually is, so all such will count as continuing objects.

temporal gaps are plausible: what is important is rather which is the best situated in relation to the original

[continues along piaget’s experiments, an objects disappears behind a screen and another appears after a time interval, people tend to believe that this was the former one, but then when two objects appear? which one is the continuer?]

... quandary about temporal overlap is intrinsic, I believe, to any notion of identity applicable to more than atomic-point-instants. Any such notion trades off depth to gain breadth; in order to encompass larger entities, it sacrifices some similarity among what it groups together. Maximum similarity within the groupings would limit them to atomic-point-instants. The purpose of the identity notion is wider breadth, but a grouping that included everything would not convey specific information. The closest continuer theory is the best Parmenides can do in an almost Heraclitean world.

The notion of identity itself compromises between breadth and (exact) similarity (which similarity can include being part of the same causel process). Since spatial and temporal distances involve some dissimilarity any temporal or spatial breadth involves some sacrifice of (exact) similarity. For our cases, width and breadth are measured along spatiotemporal dimensions, closeness or similarity along other dimensions. The informativeness of a classification varies positively with the extent of its sub-classes, and with the degree of similarity exhibited within each subclass; similar norms apply to the clumping of entities from the flux.

The alternative to a closest continuer schema is Heraclitean flux, down through all levels, if it becomes legitimate, because necessary, to use the schema at some low level then why not simply begin with it?

[closest predecessor and mono-relatedness:]

In addition to the closest continuer, we also must focus on the closest predecessor, for similar reasons. Something y may be the closest continuer of another thing x even though x is not y's closest predecessor. Though nothing at t2 more closely continues x than y does, still, y more closely continues z at t1 than it does x at t2). For a later stage y to be part of the same continuing object as an earlier stage x, not only must y be the closest continuer of x, also x must be the closest predecessor of y. Let us say that two things or stages so related are mono-related. This mono relation need not be transitive, since neither closest continuer nor closest predecessor need be transitive.

How shall a view of identity over time cope with these nontransitivities of mono-related, closest continuer, and closest predecessor? Let X refer to the entity over time that continues x at t1. I see the following four possibilities.

1. Entity X follows the path of closest continuation.... Entity X is constituted from moment to moment by the closest (and close enough) continuer of the immediately preceding component of X....
2. Entity X follows the path of closest continuation, unless it is a short path. If a tn+1 is reached when there is no continuer of the component at tn of X, then backtracking occurs to the nearest component C of X for which there exists at tn+1 something z which continues C closely enough to be (identical with) it. The component at tn+i of X is then z, and X continues from z on the path of closest continuation. At tn+i, there is a "jump" to the segment of the path that z begins.
3. This alternative is like the preceding one, except that between the lime of C and tn+1, the components constituting X are some continuation path of C that leads to z, without jumps. (Each succeeding step from C will be to a continuer, but not all will be to an adjacent closest continuer.)
4. Entity X originates with x at t1 and each later component of X is the j closest continuer existing at that time of the original x at t1. Since everything harks back to x at t1 there may be considerable hopping, either around or back and forth.

[thought experiments:]

[application of closest continuer to theseus' ship problem:]
The planks of a ship are removed one by one over intervals of time, and as each plank is removed it is replaced by a new plank. The removal of one plank and its replacement by another does not make the ship a different ship than before; it is the same ship with one plank different.
Over time, each and every plank might be removed and replaced, but if this occurs gradually, the ship still will be the same ship.

It is an interesting result, but upon reflection not so very surprising, that the identity of something over time does not require it to keep all the very same parts. It turns out that the planks removed had not been destroyed but were stored carefully; now they are brought together again into their original shiplike configuration. Two ships float on the waters, side by side side. Which one, wondered the Greeks, is the original?

In the case of the ships, there are two relevant properties: spatiotemporal continuity with continuity of parts, and being composed of the very same parts (in the same configuration).
If these have equal weight, there is a tie in closeness of continuation.

Neither, then, is the closest continuer, so neither is the original ship. However, even when the two properties receive equal weight, if there actually had been one ship existing without the other, then it, as the closest continuer, would be the original ship. Perhaps the situation is not one of a clear tie, but one of an unclear weighting.

[so he goes on to the defects of our powers of understanding..] 0ur concepts may not be sharp enough to order all possible combinations of properties according to closeness of continuation. For complicated cases we may feel that which is closest is a matter to decide, that we must sharpen our concept to settle which is (identical with) the original entity. It is different, though, with persons, and especially with ourselves; we are not willing to think that whether something is us can be a matter of (somewhat arbitrary) decision or stipulation.
yet the problem on a closer look seems to appear only after the second ship’s appearance

[questions about beaming:]

[nozick transfers from williams:]
We are prone, otherwise, to think that a person could enter a machine, disappear there, and appear in another machine ten feet to the left, without ever having occupied any intervening space. Williams asks us to imagine that there also had been an additional machine ten feet to the right, and at this one too had appeared simultaneously another (qualitatively) identical being. Neither of the two then would be that original person who entered the machine in the middle. Furthermore, if in that situation of double materialization, the person on the left is not the original person, then neither is he in the different situation where only one person appears on the left. The mere possibility of someone also emerging (discontinuously) on the right is enough, according to Williams, to show that anyone who emerges (discontinuously) on the left, even if all alone, is not the original person.

[beaming:]
Consider the mode of long distance travel described in science fiction stories, wherein a person is "beamed" from one place to another. However, the person's body does not occupy intermediate places. Either the molecules of the decomposed body are beamed or (truer to the intent of the stories) a fully informative description of the body is beamed to another place, where the body then is reconstituted (from numerically distinct molecules) according to the received information. Yet the readers of such stories, and the many viewers of such television programs, calmly accept this as a mode of travel. They do not view it as a killing of one person with the production of another very similar person elsewhere. (We may suppose that those few who do view it that way, and refuse so to "travel", despite the fact that it is faster, cheaper, and avoids the intervening asteroid belts, are laughed at by the others.) The taking and transmission of the informative description might not involve the de-materialization of the person here, who remains also. In that case, the newly constituted person there presumably would be viewed as a similar duplicate.

[beaming overlap:]
Do we need to stipulate that the process of transporting by beaming by its nature, must involve the dematerialization of the original here? In the case of people, at least, a merely accidental ending of the person here may seem inadequate for continuation there; consider the case where as the information is beamed to create what is intended to be only a duplicate the original person is shot, so that (to speak neutrally) the life in that body ends. Yet, imagine a beamer which can work either way - dematerializing here or not - depending upon which way a switch is thrown. If the process with dematerialization is far more expensive, might not those who wished to travel there choose the less expensive method combined with an alternative ending (accidental with respect to the transporting process) of their existence here? I shall leave these issues unresolved now.

[cases with duplication and (half)-brain transplantation:]

[Case 1] duplicating: After precise measurements of you are taken, your body including the brain, is precisely duplicated. In all physical proper ties this other body is the same as yours; it also acts as you do, has the same goals, "remembers" what you do, and so on.
Intuitively, we want to say that you (continue to) exist in this case, and also that a duplicate has been made of you, but this duplicate is not you. According to the closest continuer theory, too, that other entity is not you, since it is not your closest continuer.

[Case 2] brain transplant: You are dying after a heart attack, and your healthy brain is transplanted into another body, perhaps one cloned from yours and so very similar though healthier. After the operation, the "old body" expires and the new body-person continues on with all your previous plans, activities, and personal relationships.
Intuitively we want to say, or at least I do, that you have continued to exist in another body. (We can imagine this becoming a standard medical technique to prolong life.) The closest continuer theory can yield this result. The new body-person certainly is your closest continue With psychological continuity and some bodily continuity (the brain is the same), is it a close enough continuer to still be you? I would say it is.

[Case 3] mind pattern transfer: As you are dying, your brain patterns are transferred to another (blank) brain in another body, perhaps one cloned from yours. The patterns in the new brain are produced by some analogue process that simultaneously removes these patterns from the old one. (There is a greater continuity - or impression of it - with an analogue process as compared to the transmission of digitally coded data.) Upon the completion of the transfer, the old body expires.
[he still believes that that could be me, although there need be no physical continuity at all]

[Case 4] half brain transplant: Suppose medical technology permitted only half a brain to be transplanted in another body, but this brought along full psychological similarity.
If your old half-brain and body ceased to function during such a trans plant, the new body-person would be you. This case is like case 2, except that here half a brain is transplanted instead of a full one; we are imagining the half-brain to carry with it the full psychology of the person.

[Case 5] half brain dead: Suppose that after an accident damages a portion of your brain, half of it is surgically removed and ceases to function apart from the body. The remaining half continues to function in the body, maintaining full psychological continuity.
Although half of your brain has been removed, you remain alive and remain you.

[Case 6 (4+5)] half brain transplant with overlap: Let us now suppose the fourth and fifth cases are combined: half of a person's brain is removed, and while the remaining half-brain plus body function on with no noticeable difference, the removed half is transplanted into another body to yield full psychological continuity there. The old body plus half-brain is exactly like the continuing person of case 5, the new body plus transplanted half-brain is exactly like the continuing person of case 4. But now both are around. Are both the original person, or neither, or is one of them but not the other?
It appears that the closer continuer in case 6 is (the person of) the original body plus remaining half-brain. Both resultant persons have full, psychological continuity with the original one, both also have some bodily continuity, though in one case only half a brain's worth.
If this one is closer, as appears, then he is the original person and the other is not. True, it feels to the other as if he is the original person, but so did it for the duplicate in the very first case. Still, I am hesitant about this result. Perhaps we should hold that despite appearances there is a tie for closeness, so neither is the original person; or that though one is closer to the original person, close enough to him to constitute him when there is no competitor (as shown by case 5), that closer one is not enough closer than the competitor to constitute the original person. On this last view, a continuer must be not only closest and close enough, but also enough closer than any other continuer; it must decisively beat out the competition.

[Case 7] Improbable random event (note that this is different from re-creation or beaming): As you die, a very improbable random event occurs elsewhere in the universe: molecules come together precisely in the configuration of your brain and a very similar (but healthier) body, exhibiting complete psychological similarity to you.
This is not you; though it resembles you, by hypothesis, it does not arise out of you. It is not any continuer of you. In the earlier cases, by psychological continuity I meant "stemming from" and "similar to". Of course, we can have the first without the second, as when drastic changes in psychology are brought on by physical injury or emotional trauma; case 7 shows the second without the first.

[Case 8] half brain transplant and temporary overlap: Half of an ill person's brain is removed and transplanted into another body, but the original body plus half-brain does not expire when this is being done; it lingers on for one hour, or two days, or two weeks. Had this died immediately, the original person would survive in the new body, via the transplanted half-brain which carries with it psychological similarity and continuity. However, in the intervening hour or days or weeks, the old body lives on, perhaps unconscious or perhaps in full consciousness, alongside the newly implanted body.
Does the person then die along with it (as in option 1 above)? Can its lingering on during the smallest overlapping time interval, when the lingerer is the closest continuer, mean the end of the person, while if there was no such lingerer, no temporal overlap, the person would live on? It seems so unfair for a person to be doomed by an echo of his former self. Or, does the person move to the new body upon the expiration of the old one (as in option 2 above)? But then, who was it in the new body for the hour or two days or two weeks preceding his arrival there, and what happened to that person?
...the closest successor of A is B, and the closest successor of A + B is D. However, the closest predecessor of D is C, and the closest predecessor of C + D is A. Neither A + B + D nor A + C + D is a mono-related entity. Taking a longer view, though, A and D are mono-related: D is the closest successor of A plus A's closest successor; also A is the closest predecessor of D plus D's closest predecessor.

A.............B
................C......................D

long-short overlap: If the old body plus half-brain linger on for long enough, three years say, then surely that is the person, and the person dies when that body expires - the duplicate does not suddenly become the person after three years. A one-minute period of lingering is compatible with the new body-person being the original person, a three-year period is not.
[this may be explained by mono-relatedness, but the overlap situations will remain problematic:]
When B and C are small in comparison, the mono-relation of A and D would seem to constitute them as part of the same entity. Thereby, is marked off an extensive entity. Are we mono-related entities that need not be temporally continuous? On this view, there could be a person with temporal parts A and D during times 1 and 3, yet that person does not exist during the intervening time 2. Something related does exist then, so this discontinuous person does depend upon some continuities during time 2, but these are not continuities through which he continues to exist then. (A watch repairer takes a watch completely apart and puts it together again; the customer later picks up his watch, the same one he had brought in, though there was an intervening time when it did not exist.)
[problems concerning law and ethics:]
This view encounters difficulties, however. C might think to himself, "Since it is unjust for someone to be punished for a crime he did not do, D may not be punished for a crime planned and executed during time 2, when D does not exist. No one will be apprehended until time 3, so it is safe for me to commit the crime without fear of punishment." Surely we may punish D for what C does. Is it B or C we punish for the acts of A? Or do we wait until time 3 and punish D? (Yet, if D certainly will escape punishment if we wait, do we punish B or C?) It would appear that D may not be punished for acts of B (unless C does not exist). However, B might assassinate a rival political candidate to bring about the election of D. If this continued a calculated plan put into effect by A, then D may be punished; but suppose B first thinks of this act during time 2, or that A planned it thinking his life would end with B, in order to ensure that the later person D who claimed to be A - falsely on A's view -would be punished for usurping A's identity. It is clear that a morass of difficulties faces the position that one continuing entity includes A and D as parts but not the overlapping segments B and C.

amnesia variations and concern

[kurgusal ayrılma (fission), birleşme (fusion), çoğalma meselelerinin bireysel süreklilik ve bireysel özdeşlik kurgumuzda yarattığı sarsıntılarla ilgili bir kafa yorma. temelde 'concern' (varlığıyla ilgili endişe) üzerinden tartışılıyor. güzel bir makale. düzgün bir özet çıkarmaya çalıştım:]

bernard williams; the self and the future; in personal identity; ed by raymond martin and john barresi, blackwell publishing, 2005, p75 [from: Bernard Williams, "The Self and the Future” pp. 161-80 from Philosophical Review 79 (1970).]

The Self and the Future
Bernard Williams

[I. body exchange:]
Suppose, through some process [machine], persons, A and B, exchanged bodies. concern about my own future doesn’t have to be conducted over body.
[deney koşulları ve açıklamalar:]
We imagine the following. The process considered above exists; two persons can enter some machine, let us say, and emerge changed in the appropriate ways. If A and B are the persons who enter, let us call the persons who emerge the A-body-person and the B-body-person: the A-body- person is that person (whoever it is) with whom I am confronted when, after the experiment, I am confronted with that body which previously was A's body - that is to say, that person who would naturally be taken for A by someone who just saw this person, was familiar with A's appearance before the experiment, and did not know about the happening of the experiment. A non-question-begging description of the experiment will leave it open which (if either) of the persons A and B the A-body-person is; the description of the experiment as "persons changing bodies" of course implies that the A-body-person is actually B.
[deney:]
persons A and B, one prize, one punishment, shelfish choice
We announce that one of the two resultant persons, the A-body-person and the B-body-person, is going after the experiment to be given $100,000 [prize], while the other is going to be tortured [punishment].
We then ask each A and B to choose which treatment should be dealt out to which of the persons who will emerge from the experiment, the choice to be made (if it can be) on selfish grounds.
[çıkarımlar:]
Suppose that,
1. A chooses that the B-body-person should get the pleasant treatment and the A-body-person the unpleasant treatment;
2. B chooses conversely
3. (this might indicate that they thought that "changing bodies" was indeed a good description of the outcome).
4. The experimenter cannot act in accordance with both these sets of preferences, those expressed by A and those expressed by B.
5. Hence there is one clear sense in which A and B cannot both get what they want: namely, that if the experimenter, before the experiment, announces to A and B that he intends to carry out the alternative (for example), of treating the B-body-person unpleasantly and the A-body-person pleasantly - then A can say rightly, "That's not the outcome I chose to happen," and B can, say rightly, "That's just the outcome I chose to happen."
6. So, evidently, A and B before the experiment can each come to know either that the outcome he chose will be that which will happen, or that the one he chose will not happen, and in that sense they can get or fail to get what they wanted.
7. But is it also true that when the experimenter proceeds after the experiment to act in accordance with one of the preferences and not the other, then one of A and B will have got what he wanted, and the other not?
8. experimenter gives the unpleasant treatment to the B-body-person and the pleasant treatment to the A-body-person.
9. Then the B-body-person will not only complain of the unpleasant treatment as such, but will complain (since he has A's memories) that that was not the outcome he chose, since he chose that the B-body-person should be well treated; and since A made his choice in selfish spirit, he may add that he precisely chose in that way because he did not want the unpleasant things to happen to "him". The A-body-person meanwhile will express satisfaction both at the receipt of the $100,000, and also at the fact that the experimenter has chosen to act in the way that he, B, so wisely chose.
10. These facts make a strong case for saying that the experimenter has brought it about that B did in the outcome get what he wanted and A did not. It is therefore a strong case for saying that, the B-body-person really is A, and the A-body-person really is B
therefore for saying that the process of the experiment really is that of changing bodies. For the same reasons it would seem that A and B in our example really did choose wisely, and that it was A's bad luck that the choice he correctly made was not carried out, B's good luck that the choice he correctly made was carried out.
This seems to show that to care about what happens to me in the future is not necessarily to care about what happens to this body (the one I now have); and this in turn might be taken to show that in some sense of Descartes's obscure phrase, I and my body are "really distinct" (though, of course, nothing in these considerations could support the idea that I could exist without a body at all).

[II. mind engineering, variations of amnesia:]

1. i am going to be tortured
2. this is announced to me sometime before torture
2.a. they also say that right before torture, i will forget that this was announced to me before,
but this doesn’t cheer me up.
(since I know perfectly well that I can forget things, and that there is such a thing as indeed being tortured unexpectedly because I had forgotten or been made to forget a prediction of the torture, that will still be a torture which, so long as I do know about the prediction, I look forward to in fear.)
2.b. i will have forgotten everything about myself at time of the torture.
2.b.1. i will remember myself but differently. i will be remembering as another living person’s past.
2.b.2. when the moment of torture comes, I shall not remember any of the things I am now in a position to remember. [this is variation (i): A is subjected to an operation which produces total amnesia]
This does not cheer me up, either,
(since I can readily conceive of being involved in an accident, for instance, as a result of which I wake up in a completely amnesiac state and also in great pain; that could certainly happen to me, I should not like it to happen to me, nor to know that it was going to happen to me.)
2.b.3. at the moment of torture I shall not only not remember the things I am now in a position to remember, but will have a different set of impressions of my past, quite different from the memories I now have. [var. (iii): changes in his character are produced, and at the same time certain illusory "memory" beliefs are induced in him; these are of a quite fictitious kind and do not fit the life of any actual person] [zihin mühendisliği versiyon1: yaratıcı]
I do not think that this would cheer me up, either.
(For I can at least conceive the possibility, if not the concrete reality, of going completely mad, and thinking perhaps that I am George IV or somebody; and being told that something like that was going to happen to me would have no tendency to reduce the terror of being told authoritatively that I was going to be tortured, but would merely compound the horror.)
2.b.4. the impressions of my past with which I shall be equipped on the eve of torture will exactly fit the past of another person now living, and that indeed I shall acquire these impressions by (for instance) information now in his brain being copied into mine. [var. (iv): changes in his character are produced, and at the same time certain illusory "memory" beliefs are induced in him; both the character traits and the "memory" impressions are designed to be appropriate to another actual person, B] [zihin mühendisliği ver. 2: mimetik]
Fear, surely, would still be the proper reaction,
(and not because one did not know what was going to happen, but because in one vital respect at least one did know what was going to happen - torture, which one can indeed expect to happen to oneself, and to be preceded by certain mental derangements as well.)
2.b.5. [variation (v):] changes in his character are produced, and at the same time certain illusory "memory" beliefs are induced in him; the result is produced by putting the information into A from the brain of B, by a method which leaves B the same as he was before [zihin mühendisliği ver. 3: kopyalama]
2.b.6. [var. (vi):] changes in his character are produced, and at the same time certain illusory "memory" beliefs are induced in him; the result is produced by putting the information into A from the brain of B, but B is not left the same, since a similar operation is conducted in the reverse direction. [zihin mühendisliği ver. 4: karşılıklı kopyalama] [i.e: body exchange, or now, mind exchange, or none, special continuity or at the same time interruption]

now, A disappears, but where? where to draw the line? somewhere between iii-iv?

discussion: I can see only one way of relevantly laying great weight on the transition from (v) to (vi); and this involves a considerable difficulty. This is to deny that, as I put it, the transition from (v) to (vi) involves merely the addition of something happening to somebody else; what rather it does it will be said, is to involve the reintroduction of A himself, as the B-body-person; since he has reappeared in this form, it is for this person, and not for the unfortunate A-body-person, that A will have his expectations. This is to reassert, in effect, the viewpoint emphasized in our first presentation of the experiment. But this surely has the consequence that A should not have fears for the A-body-person who appeared in situation (v). For by the present argument, the A-body-person in (vi) is not A; the B-body person is. But the A-body-person in (v) is, in character, history, everything, exactly the same as the A-body-person in (vi); so if the latter is not A, then neither is the former. (It is this point, no doubt, that encourages one to speak of the difference that goes with (vi) as being, on the present view, the reintroduction of A.) But no one else in (v) has any better claim to be A. So in (v), it seems, A just does not exist. This would certainly explain why A should have no fears for the state of things in (v) - though he might well have fears for the path to it. But it rather looked earlier as though he could well have fears for the state of things in (v). Let us grant however, that that was an illusion, and that A really does not exist in (v); then does he exist in (iv), (iii), (ii), or (i)? It seems very difficult to deny it for (i) and (ii); are we perhaps to draw the line between (iii) and (iv)?

Here someone will say: you must not insist on drawing a line -borderline cases are borderline cases, and you must not push our concepts beyond their limits. But this well-known piece of advice, sensible as it is in many cases, seems in the present case to involve an extraordinary difficulty. It may intellectually comfort observers of A's situation; but what is A supposed to make of it? To be told that a future situation is a borderline one for its being myself that is hurt, that it is conceptually undecidable whether it will be me or not, is something which, it seems, I can do nothing with; because, in particular, it seems to have no comprehensible representation in my expectations and the emotions that go with them.

if we deny that the A-body-person in (vi) is A (because the B-body-person is), then we must deny that the A-body-person in (v) is A, since they are exactly the same.
in situation vi, A became B, and vice versa, we are connected to the first experiment.

"There seems to be an obstinate bafflement to mirroring in my expectations a situation in which it is "conceptually undecidable" whether I occur"

the subject's difficulty in thinking either projectively or non-projectively about the situation. For to regard the prospective pain-sufferer just like the transmogrified object of sentiment, and to conceive of my ambivalent distress about his future pain as just like ambivalent distress about some future damage to such an object, is of course to leave him and me clearly distinct from one another, and thus to displace the conceptual shadow from its proper place. I have to get nearer to him than that. But is there any nearer that I can get to him without expecting his pain? If there is, the analogy has not shown us it. We can certainly not get nearer by expecting, as it were, ambivalent pain; there is no place at all for that. There seems to be an obstinate bafflement to mirroring in my expectations a situation in which it is conceptually undecidable whether I occur.

"The bafflement seems, moreover, to turn to plain absurdity if we move from conceptual undecidability to its close friend and neighbor, conventionalist decision:"

The bafflement seems, moreover, to turn to plain absurdity if we move from conceptual undecidability to its close friend and neighbor, conventionalist decision. This comes out if we consider another description, overtly conventionalist, of the series of cases which occasioned the present discussion. This description would reject a point I relied on in an earlier argument - namely, that if we deny that the A-body-person in (vi) is A (because the B-body-person is), then we must deny that the A-body-person in (v) is A, since they are exactly the same. "No," it may be said, "this is just to assume that we say the same in different sorts of situation. No doubt when we have the very good candidate for being A - namely, the B-body-person - we call him A; but this does not mean that we should not call the A-body-person A in that other situation when we have no better candidate around. Different situations call for different descrip¬tions." This line of talk is the sort of thing indeed appropriate to lawyers deciding the ownership of some property which has undergone some bewildering set of transformations; they just have to decide, and in each situation, let us suppose, it has got to go to somebody, on as reasonable grounds as the facts and the law admit. But as a line to deal with a person's fears or expectations about his own future, it seems to have no sense at all. If A's fears can extend to what will happen to the A-body-person in (v), I do not see how they can be rationally diverted from the fate of the exactly similar person in (vi) by his being told that someone would have a reason in the latter situation which he would not have in the former for deciding to call another person A.

[conclusions:]

If this is right, the whole question seems now to be totally mysterious. For what we have just been through is of course merely one side, differently represented, of the transaction which we considered before [body exchange]; and it represents it as a perfectly hateful prospect, while the previous considerations represented it as something one should rationally, perhaps even cheerfully, choose out of the options there presented. It is differently presented, of course, and in two notable respects; but when we look at these two differences of presentation, can we really convince ourselves that the second presentation is wrong or misleading, thus leaving the road open to the first version which at the time seemed so convincing? Surely not.
The apparently decisive arguments of the first presentation [body exchange experiment], which suggested that A should identify himself with the B-body-person, turned on the extreme neatness of the situation in satisfying, if any could, the description of "changing bodies."
[destroy, disperse, discontinue:]
But this neatness is basically artificial; it is the product of the will of the experimenter to produce a situation which would naturally elicit, with minimum hesitation, that description.
By the sorts of methods he employed, he could easily have left off earlier or gone on further. He could have stopped at situation (v), leaving B as he was; or he could have gone on and produced two persons each with A-like character and memories [fission!], as well as one or two with B-like characteristics. If he had done either of those, we should have been in yet greater difficulty about what to say; he just chose to make it as easy as possible for us to find something to say.
Now if we had some model of ghostly persons in bodies, which were in some sense actually moved around by certain procedures, we could regard the neat experiment just as the effective experiment: the one method that really did result in the ghostly person's changing places without being destroyed, dispersed, or whatever. But we cannot seriously use such a model.
The experimenter has not in the sense of that model induced a change of bodies; he has rather produced the one situation out of a range of equally possible situations which we should be most disposed to call a change of bodies.
As against this, the principle that one's fears can extend to future pain whatever psychological changes precede it seems positively straightforward. Perhaps, indeed, it is not; but we need to be shown what is wrong with it.
Until we are shown what is wrong with it, we should perhaps decide that if we were the person A then, if we were to decide selfishly, we should pass the pain to the B-body-person. It would be risky: that there is room for the notion of a risk here is itself a major feature of the problem.
risk and concern: problem through how we perceive the situation