In order to better understand the differentiation between these categories, I shall begin by explaining Locke's reasoning regarding the persistence of inanimate objects, followed by his theories on living things such as oak trees, and then his views on people. I shall then show some attacks on his theories, before deciding whether or not I find his ideas persuasive.

Firstly, in the case of simple, inanimate masses of matter, Locke takes a seemingly overly strict view. He claims that any collection of atoms (atoms meant in the sense of particles, not the scientific definition of atoms we know today) remains the same object only for so long as it is made up of one hundred percent identical atoms. He agrees that the atoms can "be never so differently jumbled"1 – that they can be rearranged into different shapes etc. and still remain the same mass, so long as they are the same atoms.

However, as soon as any atom is removed from, or any new atom added to, the collection it ceases to be the same mass, and becomes an entirely new object. This provision allows for the persistence through time of things such as balls of wax, one of Locke's own examples, that change in appearance according to their environment (liquid form when warmed, possibly a different shape when cooled and hardened again etc.), but also avoids the problem of the Sorites paradox.

Sorites paradox is the problem of how much of an object can be replaced, and it still remain the same object. An example would be an axe – if the handle of the axe is worn and you replace it with a new one, the axe is still the same axe, but what if you were then to replace the head of the axe also? Would it remain the same axe now that neither of its two original component pieces were part of it? This in turn gives rise to the question of how much can, then, be replaced before an object becomes a new object. Locke's strict adherence to the principle that nothing can be removed/replaced without the object changing is perhaps the only way to truly avoid this problem.

Locke's view on living but not sentient things is, by necessity, different from his view on inanimate objects. It would be absurd to assert that a tree becomes a different tree every time it loses a leaf, or grows a new branch. The theory taken by Locke on this matter depends on something more akin to continuity of function, rather than continuity of matter.

"That being then one plant which has such an organisation of parts in one coherent body, partaking of one common life, it continues to be the same plant as long as it partakes of the same life, though that life be communicated to new particles of matter vitally united to the living plant…"2

In the case of living things, such as oak trees, the element that is important to show their continued existence, as the same entity through time, is the continuation of life. Although the particles which make up the entity at any given time were almost definitely not part of the tree when it began, and will soon disappear from its make-up, they contribute to the continued functioning of the tree as the same living thing.

The organisation of the particles is also significant in the case of a tree, or other living thing similar to it. In a mere mass of matter the organisation is "only the cohesion of particles of matter any how united;"3 whereas in a living thing the particles of matter are distributed in a specific way so as to form a self-sustaining thing. In an oak tree, the particles are arranged in such a way to create a life form that can extract nourishment from the earth, and produce leaves and bark etc. thereby perpetuating its own life.

Working on the principle of continuity of function rather than continuity of matter, the tree can change to any degree, so long as the change is simultaneous with the tree's normal biological function, and is gradual rather than a sudden replacement of the entire tree with another completely different one.

With people, however, persistence through time presents more of a problem. Locke doesn’t accept simple biology as proof of continuity. It is not enough for the body to remain the same – continuity of function in a similar way to the oak tree – for appearances to be maintained and one biological life to continue.

In order to explain what Locke considers the salient points regarding human continuity, he appeals to the difference between the concepts of 'human being' and of 'person'. One single biological entity that continues through time remains the same human being in a purely mechanical sense. The body is the same body, although particles of matter have been lost and replaced. This does not, however, assure that the entity is the same person.

Defining a person, according to Locke, depends on more than biology, it depends on perception of self, and continuity of mind: "…we must consider what person stands for, which, I think, is a thinking intelligent being, that has reason and reflection, and can consider itself as itself, the same thinking thing, in different times and places…"4

This definition of person suggests that, to be legitimately considered a person, one must be able to recall the past from one's own, unique, introspective point of view. One must also be able to envision continued existence, through some conception of future, and use reason to solve intellectual problems.

Therefore, a human being is only a person if s/he has continuity of personal perception. Take, for example, a case in which a man committed a crime, and then his consciousness was immediately swapped with that of another man. Under Locke's definition of person, the man now inhabiting the body that committed the crime would not be responsible for what his new body had done. The man that committed the crime, now inhabiting a new body, would continue to be the guilty party, despite his change of physical appearance. This seems sensible, as it requires assignment of blame to the part of the person who consciously chose to break the law, rather than the person who now inhabits the body of the criminal.

Locke's arguments for the distinction between persistence of people and persistence of oak trees initially appear persuasive. It is intuitive to say that the mind and perception must be involved in identity. There have, however, been several compelling attacks on the assertions made by Locke in his "Essay Concerning Human Understanding".

Memory is an integral part of Locke's argument. Continuity of consciousness depends heavily on our own intimate access to our own past experiences, through our memories. In contrast with Descartes, who believed that continuity of memory was merely a sign of personal identity caused by continuity of soul, Locke believes that possession of the same soul is immaterial – as long as one's memories and perception of self remain throughout one's life, then one is the same person.

Thomas Reid, an 18th century Scottish philosopher, in his "Essays on the Intellectual Powers of Man", challenged Locke's view by attacking this focus on memory through the example of the 'Brave Officer'. 5

Reid describes a situation in which a soldier was caned at school as a boy, took a standard from the enemy during his first campaign, and was made a general when he was older. He then instructs the reader to imagine that when the officer took the standard, he remembered being caned at school, and that when he was made a general he remembered taking the standard, but that between the time of taking the standard and being made a general, he lost all recollection of being caned.

This situation would result in the theory, if we obey Locke's principles for continuity of person, that the man who took the standard is the same person as was caned at school, and the man who was made a general is the same man as took the standard, and yet the man who was made general was not the same person as the boy who was caned at school. This is a logically incoherent view - it is not possible for A to equal B, and B to equal C, without A equalling C.

Another objection to Locke is presented in the form of 'Interrupted Consciousness'6. Do we really wish to say, as Locke commits himself to through his reasoning, that if a person loses their memories they lose their personal identity, and become an entirely new person? If Locke believes that continuity of memory is what makes a person one person over time, the loss of memory would result in the loss of person.

Similarly, imagine a case of head trauma. A child, for example, falls out of a tree whilst playing with her friends and is knocked unconscious. She is taken to hospital, and when she awakens, she claims to remember climbing the tree, but does not remember falling. Does this mean that, although she undoubtedly is the girl who is in the hospital with injuries caused by falling from a tree, and she is the girl who climbed the tree, because she recollects both of these events, she is nonetheless not the girl who fell from the tree, because she fails to recall it?

Unless you wish to argue for some sort of case in which the gaps in memory can be bridged through logical assumption – she climbed the tree, she has falling-from-tree injuries, therefore she must be the girl who fell from the tree – Locke's theory seems to falter in cases of memory loss.

Bishop Joseph Butler presents another interesting objection, which I find difficult to argue against – that of circularity. Locke insists that our memory of our own experiences is what makes us the same person over time, but Butler points out that the ability of have experiences and consider them to be our own presupposes the existence of a personal identity. If it did not, then we would be unable to conceive of the idea of the assignment of experiences to ourselves.

Fusion and fission, in which one person contains the memories of two other people, or one person is copied into two other people, also present helpful arguments, which I am unfortunately unable to deal with, for lack of space. Similarly, there is the difficult point regarding the fact that Locke's definition of person would not assign this status to children, or the mentally handicapped.

The number of compelling arguments presented against Locke appear to show that, although intuitively acceptable, his conception of personal identity contains several flaws that cannot be worked around. I, therefore, do not find Locke's arguments persuasive.

Footnotes:

1. Locke; "An Essay Concerning Human Understanding; Book 2, chapter 27, paragraph 3
2. Locke; "An Essay Concerning Human Understanding; Book 2, chapter 27, paragraph 4
3. Locke, "An Essay Concerning Human Understanding; Book 2, chapter 27, paragraph 4
4. Locke, "An Essay Concerning Human Understanding; Book 2, chapter 27, paragraph 9
5. Reid; "Essays on the Intellectual Powers of Man", 1785, in Perry (ed.) 1975, pages 114-115
6. Williams; "The Self and the Future", 1970, in Perry (ed.) 1975, pages 185-186



Bibliography:

Locke, John; An Essay Concerning Human Understanding; Everyman Publishers, 1947.

Perry, John (ed.); Personal Identity; University of California Press, 1975.