Locke on Identity
In Chapter 27, entitled Of Identity and Diversity, of his work Essays Concerning Human Understanding (1689), John Locke investigates the nature of identity. What does it mean for a thing to be the same? According to Locke, the conditions for identity differs according to the type of a thing. It depends on how a thing exists.
Material substances exist if they consist of the same arrangement of atoms. Once it has physically changed, it is no longer the same thing. However some types of things, which consist of material substances, change while retaining identity. For example, a plant grows and decays over its lifetime, and yet the plant retains its identity. According to Locke, the principle of identity for plants is “partaking in one common life.” Locke makes the same claim for animals, except that animals also retain certain mechanisms that enable certain functions. Whereas animals move and function in the world, a plant merely grows. But what about man? What does it mean to be the same man?
Locke argues that man is not simply a rational animal. Some animals are rational, and so, man must be more distinctly determined. Even more so, Locke says we must distinguish between “man” and “person.” A man, according to Locke, is makeup of the body and the soul. A person, however, is uniquely determined by consciousness.
The same consciousness entails the same person. Consciousness is the being conscious of one’s past actions and current being. For example, I remember riding a bike when I was 10 years old. I am the same person now because I retain the memory of that being the boy riding the bike. In the same way, I claim responsibility for my past actions through my identity.
If I commit a crime and am conscious of committing it, then I am guilty because I am the same person who committed the crime. However, if I don’t remember committing it (either through amnesia or being drunk), then Locke argues that I was not the same person while committing it then the present instance. Therefore I am innocent. In short, this means that punishment can only be applied to a person (and not a man). Locke believes the distinction between “man” and “person” is often conflated in law giving.
Another interesting circumstance involves sleep. According to Locke, you are not the same person when you are asleep versus when you are awake. This is due to the fact that you retain different consciousness during these different modes of being. Thus, if I sleep walk and eat food in the fridge and then go back to bed, and upon waking up find the food eaten, I can justly say that I did not eat the food. However, I would also be right in saying that the man who I am ate the food. Thus distinguishing identity conditions between “man” and “person” can cause confusion.
In total, Locke argues that identity, or sameness, of a thing depends on the type of thing and how it exists. A material substance is the same if it consists of the same atoms. A plant or animal are the same if they retain the same unifying body and life. However, a person is the same if that person retains the collection of memories that enables him to take account of his past actions.
