Fluid Identity

By Mitchell Creelman

Abstract: In this paper I propose a novel view on the persistence of identity through time. I propose that an object is defined by a certain set of basic properties, that these properties are maintained throughout the life span of the whole, and that the whole does not cease to exist due to the replacement of individual parts. Given the constant change throughout the persistence of a single whole, I call this idea of identity “Fluid Identity.”

Throughout this paper, I will outline the concept that I call “fluid identity,” which I will define as the idea that an object remains the same as it persists through time, even though it may be made of different parts. The idea of a whole object being comprised of different parts is known as ens successivum. There are three factors that determine a person or object’s identity; basic properties, temporal continuity, and physical continuity. The question I am interested in is when does an object cease to exist. To answer this, we must know what it is for an object to exist, how it continues its existence, and finally, when can we say that an object has ceased to exist.

An object begins to exist once it posses those properties which are most basic to it. We will define those properties as actions and/or characteristics that are most important to what it means to be any given object. For an example a bird flies, lays eggs, sings, has feathers, wings, hollow bones, etc. How does this apply to organisms as well as objects? The answer is that throughout the evolutionary process, an organism develops and adapts to its environment, resulting in a combination of characteristics, which are unique to that specific type of organism. These characteristics, coupled with the physical and temporal continuity of the object maintain the object’s existence. It is extremely difficult for an organism to cease existing without dying. While all three of the factors that determine an object’s existence are important, an object’s basic properties are the most crucial.

Here I would like to reference some points from Chisholm’s paper on the idea that a whole can persist even though its parts are changing. (Chisholm) Chisholm gives a very thorough, almost mathematic argument, which starts by looking at a table where leg A is connected to joint B on Monday, forming combination AB. On Tuesday, leg A is replaced by leg C, resulting in the combination BC. On Wednesday, leg joint B is replaced by joint D, resulting in the combination CD. The process is carried out so that there is always a table to be found during the process. Although this table consists of completely different parts at different times, it would seem absurd to say that it is not the same table. Clearly, despite the changing of the pieces, the table as a whole persists. So then what does this mean?

This means that some properties, which define an object, are not always rooted in the present, but can be rooted in the past or future. In the case of the table, on Monday, it has the property that it will be table BC on Tuesday, and will then be table CD on Wednesday. Yet on Tuesday, the table has the properties of having been AB, currently being BC, and going to become CD. What makes this specific table unique is the connection of all of its temporal parts.

The same goes for people. In my past, I had the property that I would one day become the person I am now, and that I will then become a person that exists in my future. But now, I posses the properties of having once been a child, and that I will become a person who exists in the future. Whether we apply this to the physical composition of a person, or the mental composition, it is still true that these different parts are all part of a whole. However, this change is not instantaneous, and is a result of the gradual alteration, we are far more related to our temporally local selves than to our temporally distant selves. Like a rock that sits in the river, surrounded by flowing water, we remain certain of the existence of our present selves, but that which we refer to as our present self changes throughout our lifetime. It is this maintaining of a single consciousness in spite of our changing bodies, environment, and even personality that allows for our identity to have a “fluid” property.

From this point on I will be using the example of the ship of Theseus to explain the idea of fluid identity and relate it to organisms and people. The ship of Theseus example consists of a sailing ship, which gathers wood floating in the water, replacing itself piece by piece, until eventually it contains none of its original parts. There is also another ship behind it, which gathers the replaced parts as they are discarded from the ship of Theseus. Eventually that ship is composed entirely of the parts that originally constituted the ship of Theseus. The common questions that are raised are whether or not the ship at the end is the same as the ship at the beginning, and if at the end of the process, has the trailing ship become the ship of Theseus? My answers to these questions are yes and no respectively.

In short, the reason that the leading ship is still the ship of Theseus after every piece has been replaced, is that the ship maintains temporal continuity. The instant a part has been replaced; it becomes part of the whole. As this whole persists temporally, it has unique experiences. Once the piece joins the whole, it shares in the unique experiences of that whole. This may be a bad example because a ship itself does not have experiences. We can illustrate this through the process of cell replacement in organisms. Immediately after a cell is replaced, it becomes part of the whole, which has its own experiences and identity. The longer the piece remains as part of the whole, the more certain we are that it is part of the organism.

But what happens if we replace a significant number of parts on the ship? Does it remain the same vessel? As long as at least some of the pieces that constituted the ship in the previous instant are still present, the ship remains in existence. If we look at the half waypoint in the ship of Theseus examples, it would be strange for us to say that the trailing ship is half its former self and half of the ship of Theseus at the half way mark during the process. Likewise, it would also seem strange to say that only half of the ship of Theseus remains at this same point. This is not to be confused with saying that half of the trailing ship was constructed of pieces taken from the ship of Theseus. The only way that a ship can cease to exist through the replacement or repair of its parts is if a very large percentage of its parts are instantly replaced, which I will comfortably state to be impossible. The exact percentage that constitutes this can be seen as arbitrary so I will not be taking the time to elaborate in this paper.

This shows that the concept of identity exists in degrees, which is why I refer to the idea as “fluid identity”. Even though our bodies are being replaced piece by piece, we still persist as the same person throughout our lives. One way that we could do this is through looking at person stages as the idea that a person is more similar to their immediate past and future than they are to the distant past and future versions of themselves. One example of this is the Methuselah objection, as illustrated in David Lewis’ paper “Survival and Identity.”

In his paper, Lewis supposes that Methuselah is a being who lives 969 years, but is plagued with a poor memory. As a result, he can only remember 137 years into the past. As a result, segments of Methuselah’s life are related if and only if they are 137 years apart. This means that only the 137 year segments are constituent persons. But this is where I disagree. It seems counter-intuitive to say that just because there is no memory of a stage of life does not mean that it is not part of the same person. As children, we remember little to nothing before a very early age. Are we ready to say that we have absolutely no relation to the infant/childhood versions of ourselves? Rather, I propose that we are always have some relation to all of our temporal parts, but it decreases as time goes on. You are not so different from the person you were a few moments before reading this paper, yet you are a vastly different person from the one you were in fifth grade. The reason that this is true is that change in identity is not an all or nothing question. A person experiences changes slowly throughout their lifetime.

One issue that comes up is what happens if the ship’s form changes, for example, if a mast is added or taken away. This is a case that will be solved by referring to the idea of basic properties. As long as the ship’s form allows it to fulfill the basic properties of a ship (ie. as long as it can sail), it still exists as the same ship it has always been. The only way that the ship would cease to exist would be if its form were changed so dramatically that it could not serve its basic function.

Let’s say that the ship of Theseus was changed piece by piece until it was no longer a ship, but a solid sphere of wood and nails. Intuitively we would say that the ship of Theseus is no long existence since such a contraption clearly could not sail. But when does this cessation occur? My answer is the moment in which the ship loses its ability to fulfill its basic function.

This brings me to what I call the rudder objection. This is a case in which the rudder of the ship has broken off, leaving the ship unable to sail. The ship is still composed of the same parts it was the moment before, is still mostly in the original form, but in such a condition that it can no longer fulfill its basic functions. My answer to this is that the ship’s form has not changed enough to make it completely useless. Despite the issue of a crucial component being absent as long as it is possible to repair the ship to its former state, the ship continues to exist, since simple parts replacement will render the ship functional once again. In contrast, no matter what the condition of the sphere, it will not sail.

So what is that property which makes us human, and by which we define our existence. This is obviously open to much debate, but for the purposes of this paper I will comfortably say that it is the ability to use higher reasoning and problem solving. Without these, a person cannot be considered human.

Now, one can ask, what happens if we simply take the ship apart piece by piece, and reassemble it back into the same form that it was in prior to being dismantled? Furthermore, what would happen if we dismantle two different ships, and use half of each to rebuild the ships? This process of dismantlement will be hereafter referred to deconstruction. The process of reassembling the ship will be referred to as reconstruction.

I will start by answering the second question since the answer is short. The answer to this question is the same as it is in cases of fission, which I propose is that two new ships are created, while the original is destroyed. In the case of human fission, this would mean that the original ceases to exist, and two new entities come into being.

As for the first question, I feel that the answer is that the ship ceases to exist once the ship can no longer possesses its basic properties after the process of deconstruction has begun. The deconstruction process begins as soon as pieces of the ship have been taken off and are not replaced. It is true that each piece retains the property of having once belonged to the ship of Theseus. If we build a table from the pieces, we would say, “This table was built from the ship of Theseus.” Yet even after being reconstructed, it would not be the same ship. This is because it would be impossible to reconstruct the ship exactly as it was before the deconstruction process began. To once again be the ship of Theseus, every plank, nail, rope, sail, and every other component would not only have to be in the same location it was in before the process began, but would also have to be in the exact same condition. It would be extremely unlikely, if not impossible, for every piece to be exactly as it was originally, so it is impossible for it to be the same ship. However, we can say, “this ship was constructed from all of the pieces that made up the ship of Theseus.”

It is also worth mention that once an object has ceased to exist, it cannot come back into existence. As I said before, we can say that the new ship is made from the ship of Theseus, but we cannot say that the ship itself is actually the same ship.

Works Cited

  1. Lewis, David. “Survival and Identity.” Ontology. 1976. 55-76. Print.
  2.  Chisholm, Roderick M. “Chapter 3.” Person and Object: A Metaphysical Study. La Salle, IL: Open Court Pub., 1976. 89-113. Print.
  3. Special Thanks to
    • Bradley Monton
    • David Barnet

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