A simple revision to Locke's theory solves this. If we think of personal identity as an overlapping chain of memories it would show us that although the old general does not remember the time when he stole an apple as a child, he is still the same person, as he does remember himself as a soldier receiving a medal – a time where he could remember himself stealing an apple as a child. Although there are still problems with memory theory, the duplication argument demonstrates this. If we imagine a teletransporter, a device which can destroy and recreate your entire physical structure with memories, in a different location, Locke’s theory would suggest that you would still be the same person. Although what if, instead of destroying your body, the teletransporter just recreates you in a different location. Locke's theory would suggest that the two people would be the same persons, although this is logically impossible, as one person cannot be two people.
The only other possibility is for personal identity to be physical. There are two arguments supporting this, the first of the two physical theories suggest that being the same person means being the same human animal. This initially makes sense, as this is the primary way in which we re-identify with people. Although upon further inspection this argument is problematic, as if we consider a situation where my brain were to be transplanted into your body, and your brain were to be transplanted into my body, the animal theory would suggest that you would have my brain, rather than I have your body, which would make more sense logically.
The second physical theory suggests that it is a matter of having the same brain. This does not even have to be the same brain, as under some circumstances the brain can still function if a part was removed, so you would only need enough of the brain to support the mental characteristics of personhood. However, if we consider a scenario where your brain was reprogrammed with all my memories, and my brain was reprogrammed with all of your memories. Brain theory would suggest that you have my memories, rather than you having my brain which would make more sense.
It seems as though there a various problems with both physical and psychological continuity, no features can be changed without changing the underlying self. As Hume argued, the self is just a bundle perceptions, so there is in fact no personal identity, rather it is an illusion created by the connectedness of mental states. We cannot successfully argue that a person is strictly identical over any stretch of time. Personal identity is, it seems, indeterminate – whether or not we decide to say that someone is the same is not something with a definite answer, it is something which depends on the nature of the case.
