Impersonal Identity

Impersonal Identity

We normally think that bodily survival depends upon identity through time. The body of an animal may change over time, but the body remains one and the same through these changes; the animal doesn’t acquire a numerically distinct body as it goes through life. Even in death the body remains one and the same object (though the organism may be no more). The body of the animal survives death by being identical to an earlier body, going back to the womb. Only when nothing identical to the earlier body exists does the body cease to exist. But what should we say about fission cases? Suppose the body divides into two, either naturally or by artificial intervention: then we have a problem with identity as a criterion of survival. For we cannot say that the later bodies are each identical with the earlier body, since they are not identical with each other; and it seems funny to say that one body could be identical to two bodies taken together. Yet it would surely be an exaggeration to claim that in such a case we have no survival—as if fission cases are just like incineration cases. It seems right on balance to say that the fission of a body allows for survival without identity. That position is reinforced by noting that fission might be succeeded by fusion: the pieces might be put back together again just as they were in the pre-fission body. Surely that would be the very same body that had recently divided into two. The original body had survived even though for a while nothing was identical to it. Bodily survival does not logically require bodily identity over time.

            This conclusion applies to more than just animal bodies. You can divide a statue into two for purposes of ease of transportation, later to be reassembled, and the case is clearly one of survival without identity (the statue survives as two pieces). Likewise for a rock or a plant. Similarly for a club or nation: such social entities can divide and remain in existence. Secession is not cessation. If a club decides to operate henceforward as two clubs, this is not like disbanding the club altogether; it might just be a convenience so to divide, as when a tennis club decides to split into a doubles club and a singles club. The reason for this is that fission involves continuity: the parts of the original entity survive as separate entities. Wherever there is fission there will be survival without identity, because identity is a very demanding relation; there are relations that fall short of it where we still have continued existence. Identity obeys Leibniz’s law, but mere survival does not. If you take apart your bicycle, you don’t destroy it utterly; it may be expressly designed to be taken apart. Nor do you destroy a cake by cutting it into pieces, even though the original cake is not identical to any of its pieces (they are not identical to each other). There is nothing strange or paradoxical here: given fission, survival without identity is what we should expect.

            The survival of persons follows the same pattern. Generally survival coincides with identity through time, but in fission cases (split brain) these come apart. Then we have survival in the shape of erstwhile parts that persist, as when the two halves of the brain are implanted into different bodies. The original brain is not identical with either hemisphere, and it is odd to say that it is identical with both together.[1] But nothing here is surprising once personal fission has been mooted: brains can be divided, and when they are we have survival without identity. Suppose Jekyll resides in one half of a person’s brain and Hyde in the other. When the brain is split and the halves placed in different bodies two persons are formed, but the original person survives the procedure (unlike the case in which the original brain is simply burned to ashes). Nothing here shows anything distinctive or remarkable about persons as such; certainly they are not the onlythings that can survive without benefit of identity. If persons were simple indivisible entities, then fission would not be possible for them; but evidently this is not the case. In fact, the idea of split personality already provides space for such a possibility, given that the two (or more) personalities might come to inhabit distinct bodies. The potential for fission is present in cases of split personality, and it provides an example of survival without identity if the personalities come to occupy distinct bodies. I think this is implicit in our ordinary concept of a person, because we recognize that conflicting psychological traits can coexist inside the same human organism (as with selfish and unselfish traits). All is not harmony within, as many a human story illustrates. Once we envisage dividing an individual into separate unified psychological wholes we are preparing the ground for survival without identity. This is not some startling piece of anti-commonsense philosophy but part of our ordinary folk psychology—which is the story of Jekyll and Hyde makes sense to us. It is true of each of us that if we had our brains suitably rejigged and placed in different bodies, then we would survive without any future person being identical with the person we now are. In this respect we are like the rest of nature.

[1] Even if it were, we could still destroy one and have a case of survival without identity.