Let us assume that you are about to undergo an operation and that you still have a decision to make. The utilities involved are, first, financial -- you wish to avoid any needless expense -- and, secondly, the avoidance of pain, the avoidance, however, just of your pain, for pain that is other than yours, let us assume, is of no concern whatever to youl The doctor proposes two operationg procedures -- one a very expensive procedure in which you will be subjected to total anaesthesia and no pain will be felt at all, and the other of a rather different sort. The socond operation will be very inexpensive indeed; there will be no anaesthesia at all and therefore there will be excruciating pain. but the doctor will give you two drugs: first, a drug just before the operation which will induce complete amnesia, so that while you are on the table you will have no memory whatever of your present life; and, secondly, just after the agony is over, a drug that will make you completely forget everything that happened on the table. The question is: Given the utilities involved, namely the avoidance of needless expense and the avoidance of pain that you will feel, other pains not mattering, is it reasonable for you to opt for the less expensive operation?
Fragt Roderick Chisholm in einem Aufsatz Identity through time (S. 163-182, hier S. 178, in: Language, belief, and metaphysics, ed. by Howard E. Kiefer and Milton K. Munitz, Albany : State University of New York Press, 1970). Chisholm präsentiert das Gedankenexperiment, dass er Peirce zuschreibt (Collected Papers V (1935), 355), als Frage nach der Identität durch die Zeit: man könnte ja so tun, als sei die Zeit zwischen den beiden Amnesien die einer anderen Person. Könnte man: würde man aber nicht, wie Strawson in seinem Kommentar dazu anmerkt.
Chisholm präsentiert noch eine zweite Geschichte (S. 179):
Suppose you know that your body, like that of an amoeba, would one day undergo fission and that you would go off, so to speak, in two different directions. Suppose you also know, somehow, that the one who went off to the right would experience a life of great happiness and value. If I am right in saying that one's question "Will that person be I?" or "Will I be he?" always has a definite answer, then, I think, we may draw these conclusions: There is no possibility whatever that you would be both the person on the right and the person on the left. Moreover, there is a possibility that you would be one or the other of those two persons. And finally, you could be one of those persons and yet have no memory at all of your present existence. it follows that it would be reasonable of you, if you are concerned with your future pleasures and pains, to hope that you will be the one on the right and not the one on the left -- also that it would be reasonable of you, given such self-concern, to have this hope even if you know that the one on the right would have no memory of your present existence. Indeed it would be reasonable of you to have it even if you know that the one on the left thought he remembered the facts of your present existence.
Was zeigt das? Strawson: "to conclude from this that there is such a thing as strict criterionless personal identity through time wold simply be an enormous non sequitur."