In this chapter I will demonstrate that the bodily criterion alone is not sufficient for continuation of identity, by describing the limits of acceptable physical change. However, I will also show that some form of physical continuation is necessary, such as a person’s genetic make-up.
Some materialist philosophers (such as Eric Olsen) have claimed that the physical body is the seat of the identity. This view claims that as long as one keeps the same body throughout their life, they are guaranteed to maintain their unique identity.
This approach makes identifying selves clear and simple, as we can identify the exact spatio-temporal location of each self, as well as the starts and ends of selves. So, for example, if someone commits a crime, we can easily establish whether they are guilty or not by evidence such a fingerprints and witness testimony. As long as their body committed the crime, we are able to punish them for it.
Criticisms, particularly in light of change over time
There is a lot of opposition to the view that our identity should be limited to just the physical body. This position is contrary to most religions, which view our immaterial souls as intrinsic to our identities. The religious conception of a soul tends to be like that of consciousness, and some religions, such as Judeo-Christian religions, claim that this part of us continues to live on after the physical body has died. (As Parfitt points out,) The bodily criterion would only allow for a second life in the form of a physical resurrection or reincarnation. We certainly should not dismiss the position simply because it is incompatible with popular religions, though.
There are more damning criticisms of the bodily criterion for identity, however. Our bodies are constantly changing- growing, shedding or regenerating cells, etc. So how much of our body must stay the same in order for us to be classed as the same person we were several years ago? For example, a popular analogy was given which describes the philosopher John Locke’s favourite pair of socks, which grow holes in from being worn so often. As the holes develop, Locke repairs them with patches. But after a while of repairing his socks, none of the original material remains, and they are simply a patchwork of new pieces of material (Where is this from?). The original debate, of which Locke’s example was a variation, is that of the Ship of Theseus, which has its pieces replaced one at a time, as necessary (Plutarch, p?). Many people believe that, at some point, the Ship of Theseus loses too many of its original pieces and ceases to be the same ship that Theseus had returned from Crete in. Similarly, many believe that Locke’s favourite pair of socks cease to exist when none of the original yarns are present. But, if we are to equate identity with the body’s cells, this position claims we must develop a new identity as our bodily cells change during our lifetime. This is a bizarre position to hold, as there would be no detectable change in our appearance or attitude
Possible solutions to criticisms, and the success of these solutions
But not everyone agrees that this is the case. Many people believe that the gradual change involved in the previous examples ensures that they retain their former identity. In the case of Locke’s socks, the consensus tends to be that the resulting pair of socks are indeed the same as his favourite pair of socks, as this is the way we speak of things which have been repaired. Similarly, the gradual change of the Ship of Theseus ensures it retains its identity. As this pertains to the body, it suggests that, despite each of our cells being regenerated every ten years, this does not inhibit us from remaining the same person. This means the gradual change of our body’s cells falls within the acceptable limits of change, apparently saving the bodily criterion for identity.
Thomas Hobbes offered another variation upon this theme, whereby the ship’s planks ere replaced with aluminium (Hobbes, p.135?). The pieces removed from the ship were then reassembled to form a ‘replica’ ship. But in this example, we are more inclined to state that the ‘replica’ ship which has been assembled from the original pieces is the same ship of Theseus, while the aluminium replacement is a replica.
This is perhaps because a crucial part of the theory of bodily continuity is that it requires we maintain essentially the same genetic structure. This makes the concept of bodily continuity highly supported by the sciences, which tend to view us as biological creatures governed by the physical reactions which occur within our brains. A result of this is that, while our bodies could be perfectly but entirely replicated in a metallic form, these robots would lack our genetic code and would thus be a replica, rather than ourselves.
Genetic determinism takes this position further, and claims that who we are is entirely dependent upon our genetics. Genetic determinists suggest that a clone and his original would have the exact same identities. The effect of genetics upon one’s identity has been investigated by studies of monozygotic (identical) twins, who are genetically identical. While studies of monozygotic and dizygotic twins have previously suggested that up to 50% of our personality is genetic (ref?), most twins tend to be raised in similar environments, making it difficult to separate the influences of nature and nurture. But studies of monozygotic twins who have been raised separately indicate that only 20 to 25% of our personality is genetic in nature (Ewen, p. 73).
So we have established that the gradual regeneration of our cells during our lives falls within the realms of acceptable change, whereas being replaced with a non-human body (for example, a metal one) does not.
So where exactly are the boundaries for changes we deem to be acceptable? How much of our body could we lose without losing our identity? Bernard Williams describes the physical spectrum, where a person’s body is replaced very gradually. He claims that this example is subject to the heap paradox. In the same way removing a grain from a heap does not stop it from being a heap, it seems that each change is too small to change our identity. Yet by the end of it the person’s body has been replaced with that of Napoleon’s.
In this example, Williams describes the physical changes which occur to the subject of this experiment, but not the psychological effects. While his body has been replaced with that of Napoleon’s, he may well still maintain all the same character traits and memories we associate with his original self.
While this is a very radical example, it does have practical implications. If a certain amount of our body is required to stay the same for us to remain the same person, this raises questions about amputees and people who undergo extensive plastic surgery. For example, what if a man had his arms amputated, and then his legs? Would he still be the same man he was prior to these operations? While he may now lack many of the skills he had before, it seems unfair to claim he is not the same man. What if he was somehow reduced to simply his head, though? Some claim that it is not the whole body which is required for continuity of the self, but a very small part of it: the brain.
This objection was raised by Sydney Shoemaker, who describes a thought experiment regarding Brown and Robinson. Brown undergoes a brain transplant, and his brain is placed in the body of Robinson. When Robinson’s body awakes, it remembers everything of Brown’s life, behaves like Brown, has the same beliefs as Brown, and even adopts all the mannerisms his family have come to associate with him. It seems that Brown and Robinson’s family alike must agree that Robinson’s body is now home to Brown’s identity.
While this is a very extreme case, it does demonstrate that the body alone is neither a sufficient nor necessary condition for the continuity.
Eric Olson, however, defends the bodily criterion against this criticism, viewing the individual simply as a biological organism. He claims that humans can withstand complete psychological change and remain the same as long as they are alive for.
I disagree with this position, however. It seems to me that if you remove a person’s personality, mannerisms, memories, dispositions, etc, you have removed that person’s very identity. It seems to me that in considering the individual as a human animal, Olson oversimplifies the issue of identity. It is easy to say that the human being still exists despite this overhaul of their mental life, but it is very difficult to substantiate the claim that their personal identity has not been at all affected by this.
R. B. Ewen, Personality, a topical approach: theories, research, major controversies and emerging findings, Lawrence Earlbaum Associates Inc Publishers, New Jersey, 1998.
T. Hobbes and W. Moleworth, Elements of Philosophy, vol. 4 of The English Works of Thomas Hobbes of Malmesbury, London, J. Bohn.
H. Noonan, Personal Identity,
E. Olsen, “The Human Animal: Personal Identity Without Psychology”, Oxford University Press, Oxford, 1997.
D. Parfit, Reasons and Persons,
Plutarch, Lives, J. Langhorne and W. Langhorne (eds), Harpers and Brothers Publishers, New York, 1859.