When John Locke (1632–1704) wrote about personal identity, his reasoning was approximately as follows:1
- What gives an animal its biological identity as a human being or a cat or a parrot is the shape of its physical body, not its mentality. So even if a cat could reason like a man, we would say it is a clever cat, not a man in a cat’s body. Similarly, even if a man were no more capable of speaking than a cat, we would say that he was a dull-witted man, not that he was a cat in a man’s body.
- When we speak of a personal identity, we do not mean a person’s physical identity. Rather, when we speak of a person, we mean “a thinking intelligent being that has reason and reflection and can consider itself as itself.”
- What gives someone a sense of self is just his consciousness; it is this which distinguishes someone from other people, and it is this which stays somehow the same. So it is consciousness that gives a person her identity.
- Something more is required for a thinking substance to be regarded the same being from one moment to the next. Obviously that something further cannot be an identity of the contents of consciousness, for what someone is aware of at one moment is not exactly the John Locke, An Essay Concerning Human Understanding, ed. Alexander Campbell Fraser, (New York: Dover, 1959). same as he was aware of the moment before. We might be tempted to think that memory is the key to identity, but at any given moment our memory does not have access to every experience from the past. Memory is constantly interrupted—we remember now one thing, now another—so at any given moment we have only an incomplete access to our past selves. So this gives rise to doubt as to whether we are the same self as we were in the past.
- The issue of whether a thinking substance is the same from one moment to the next has no bearing on the question of personal identity. Different thinking substances are all united in a single person.
- The criterion for a personal self is the ability to “repeat the idea of any past action with the same consciousness it had of it at first, and with the same consciousness it has of any present action.”
- A man may lose part of his physical body without undergoing any change in his sense of personal identity. This shows that personal identity is not based on the composition of one’s body.
- If someone were committed to materialism, then he would have to hold the view that one’s personal identity is situated entirely in the physical body, for this would remain the same even if the thoughts contained in it underwent change.
- If someone is committed to a position of mind-body dualism, then he might see the possibility that one and the same soul could occupy more than one body. And if a dualist accepted this, he might then say that a person can retain her identity despite undergoing a change of bodies. Locke says he sees no reason why this could not be the case.
- It is even possible that a mind-body dualist could hold that a conscious soul could first occupy one body and then occupy a second body but lose all memory of its actions in the first body. So here the soul could remain the same despite no continuity of access through memory to its previous states. Plato and other philosophers who believed in reincarnation held a view along these lines.
- If anyone thinks about the matter, he will see that “he has in himself an immaterial spirit, which is that which thinks in him and in the constant change of his body keeps him the same as is that which he calls himself….” Now, if there is no access to the memories of a previously existing person, then there is no basis for saying that one has the same personal identity as that previous person, even if it did turn out that one had the same soul. In other words, the soul could transmigrate, but in doing so it would change personal identities.
- If, on the other hand, the soul did retain the memories of its actions in a previous body, then we could say that the same person had a succession of bodies. What this possibility does is to preserve the possibility of a physical resurrection in which the resurrected body did not contain any of the same atoms as the body originally occupied by the soul.
- “Self is that conscious thinking thing…which is sensible or conscious of pleasure and pain, capable of happiness or misery, and so is concerned for itself, as far as that consciousness extends.”
- Personal identity is an important matter, because it is the foundation of all concepts of rights, justice, rewards and punishments. It is not the physical body that determines one’s personal identity, and so the physical body is not the foundation of rights, justice etc.
- Similarly, it is not the soul that determines one’s personal identity. If, for example the soul were to transmigrate from one body to another, but there were no memory when in the second body of what it did in the previous body, then there would be no justice in punishing the second body for the deeds of the first body.
- If a man were to completely lose all memory of actions performed in an earlier stage of life, then there would be no justice in punishing the later man for what he did earlier in his life. In this case we would say the man remains the same, but he has undergone a change of persons. So if a person were to go completely mad, it would not be just to punish him for actions that he did while sane, or vice versa.
Locke summarizes his position in these words:
Person, as I take it, is a name for this self. Wherever a man finds what he calls himself, there, I think, another may say is the same person. It is a forensic term, appropriating actions and their merit, and so belongs only to intelligent agents, capable of a law, and unhappiness and misery.
Joseph Butler (1692–1752) said of Locke that his identification of the person as something that depends on the memory is unsatisfactory, because it places all emphasis on the past and fails to take into consideration our all our aspirations for the future. Butler was a Christian bishop who was concerned with the afterlife, but he said that even if one thinks only in terms of this life, it is very common for people to plan for their old age and to have aspirations as children for their adult lives. Locke’s account of personhood does not take this sufficiently into account. As he describes personhood, the person for whose retirement a young person is saving money would be more remote and abstract than one’s own parents or siblings. In other words, Locke gives you no rational basis for making decisions today that could have an impact on your health and well-being even tomorrow, let alone a few decades from now.
Criticisms of Locke notwithstanding, his criterion of personhood or selfhood has proved to be the most durable candidate. Although not many philosophers accept it exactly as Locke stated it, most philosophers use his view as a basis and then refine it in various ways, usually by making an appeal to some version of the concept of causal continuity. The decisions you make now are the beginning of a causal chain, the effects of which will be experienced by an older person in a way that they will not be experienced by, say, your cousin or your roommate. That future person who will experience the effects of what you decide to do now will be an older version of yourself; that is, that person will (still) have your personal identity.
The next Western philosopher whose views on self and personal identity are to be considered is Derek Parfit.
- John Locke, An Essay Concerning Human Understanding, ed. Alexander Campbell Fraser, (New York: Dover, 1959). ↩︎
- Locke, John. An Essay Concerning Human Understanding. ed. Alexander Campbell Fraser. New York: Dover, 1959.