Philosophy Things

The Unity of Self

In his book Philosophical Explanations, Robert Nozick presents a “closest continuer” theory in an attempt to explain what the unified self is. In this theory, Nozick uses the example of a wooden ship and shows how it is analogous to any kind of natural unity. Nozick presents a scenario of a ship whose planks are removed one by one over intervals of time, and every plank that is removed is replaced with a new plank. He explains how, even if eventually every piece of the ship is a replacement, nobody would argue that the ship at T2 is not the same ship that was at T1. However, he claims, if the removed planks were not discarded, but rather, stored neatly and later used to build an entirely “new” ship, and both ships were to be floating next to each other, determining which ship is the original would depend on which properties are used to determine closeness. If, for example, “spatiotemporal continuity with continuity of parts” is used to determine the closest continuer, then the first ship is the original ship. On the other hand, if “being composed of the very same parts” is the property used to determine closeness, then the second ship is the original ship.

The case of the wooden ship is analogous to any kind of natural unity in how the schema fits and explains how one respond to such a puzzle. Given a person with sever amnesia, for example, one could argue that he is a completely different person that before the amnesia. Conversely, one could argue under the closest continuer theory that he in fact is the same person, being that he is the “closest continuer” to the “original” that is being referred to. Under the closest continuer theory, as long as there is not a closer person that exists to the original person, the person with amnesia is the original person.

Nozick makes it a point to mention that something is not a continuer of x merely because of its qualitative properties are the same as x or resemble them. He distinguishes between those types of properties and the kind that “grow out of x’s properties” and are causally produced” by them. Given this perspective, I agree that I am a single unified person, just as the person with amnesia is. Although my physical and mental states may change, I am still the same person I was ten years ago.

I believe that what unifies me over time is, as Nozick described, the properties that grow out of my existing properties, the properties that are causally produced by prior properties, the properties that are explained by my having earlier properties, etc. I believe that all of these factors not only contribute to my believing that I am a unified person, but that they are what help me to actually be a unified person. I believe that the most important sources of my identity come from believing that I was created in the image of God, and through that knowledge, I am enabled to grasp not only the source of my identity but I am also able to explain the underlying continuity I have that makes me a unified person.