Paradoxical Thoughts on Identity and Individuation. According to early Buddhism, there is no self, and persons are not ultimately real (see: ????). This seems to be an absurd and nonsensical point of view. Most people don’t question their unique identity and regard themselves as real persons, sharply distinguished from other real persons with whom they interact daily. Moreover, most people commonly assume that their identity stays the same over long periods of time. A seventy year old woman usually takes it as a self-evident truth that she is the same person as she was sixty years ago, although her physical and psychological state has drastically changed. But must commonsense necessarily always be the final judge in answering uncommon questions? King Milinda concluded otherwise. In the story “The Questions of King Milinda” he is convinced of the non-existence of the self after a rather short chat with Nagasena.
However, we regularly say that persons and material objects can change over time, meaning that numerically one and the same thing can be qualitatively different at different times. Another famous story which forces us to rethink certain aspects of our commonsense understanding of the identity of material objects over time is the story of the ship of Theseus. It goes like this: In ancient Greece lived the legendary king Theseus who supposedly founded the city of Athens. King Theseus heroically fought many naval battles and so the Athenian people devoted a memorial in Theseus’ honor by preserving his ship in the harbor of Athens remaining there for centuries. As years went by, some of the wooden planks of Theseus’ ship started to decay. To keep the ship representable and complete in the harbor, these planks were replaced by new planks made of the same material. Here is the key question: If one of the ship’s planks is replaced, is it still the same “ship of Theseus”?
This story about the ship of Theseus is a role model for one of the most discussed problems in philosophy: the problem of identity. What is a physical object? How do things stay the same even after they have changed? When do they cease to exist? And when we speak about a particular object and say that “it changed,” what exactly is “it”? The story of the ship of Theseus became even more thought-provoking thanks to an additional scenario introduced by Thomas Hobbes. Suppose that, while the original planks of Theseus’ ship in the harbor are gradually replaced by new ones, those original planks are carefully removed and gathered in a warehouse. This goes on until the warehouse contains all of the original planks and the replacement planks belong to the renovated ship in the harbor. Then someone puts all of the original planks together to reconstruct a ship which is precisely like the original ship of Theseus. Not only is it exactly like the original ship in its appearance, like the renovated ship, it also is composed of the same planks. So now we have two ships which are very similar to each other: the renovated ship in the harbor and the reconstructed ship in the warehouse. Both seem to have a reasonable claim to be identical with the original ship of Theseus. Hobbes’ version is an example for another philosophical issue: the problem of individuation. What makes a thing one thing as distinguished from another thing?
This story is usually considered as paradoxical. According to Sainsbury we can speak of a paradox when “an apparently unacceptable conclusion is derived by apparently acceptable reasoning from apparently acceptable premises.” (????) With this definition in mind it’s undeniable that we got ourselves a paradox! Our problem is that we have two ships, both having an acceptable claim to be identical with the original ship. In the case of renovation without reconstruction we would have identified the renovated ship in the harbor with the original, because we usually allow a gradual change of objects without losing their identity or ceasing to exist. In the case of reconstruction without renovation we would have identified the reconstructed ship in the warehouse as the original, because we normally allow that an artifact can be disassembled and reassembled later, without losing its identity or ceasing to exist. But in the case of both renovation and reconstruction we can´t say that both the renovated ship and the reconstructed ship are identical with the original ship because this denies that identity is a transitive relation: If the renovated ship is identical with the original ship and the original ship is also identical with the reconstructed ship, it follows from the transitivity of identity that the renovated ship is identical with the reconstructed ship. This seems impossible because the renovated ship and reconstructed ship are distinct ships having distinct locations. On the other hand, it seems arbitrary to say that one rather than the other is identical with the original ship. How could we choose? The paradoxical nature of Theseus´ ship summarized:
Premise 1: The ship in the harbor = Theseus' ship.
Premise 2: The ship in the warehouse = Theseus' ship.
Conclusion: The ship in the harbor = the ship in the warehouse.
And so, either one thing is at two different places at once, or two things were at the same place at the same time. Paradoxical indeed! But we shouldn’t consider paradoxes as problematic but as tools to scrutinize our metaphysical and epistemological intuitions. Intuitions overloaded with premises and reasoning that are “apparently acceptable”, occasionally leading to “apparently unacceptable” conclusions. Maybe some of these ‘apparently’s´ appear to be not so apparent after all. There might be something to learn! And so, all hands on deck! It’s time to hoist the sails, explore the vast oceans of thought, gauge the depths of our knowledge and investigate where we can drop anchor.
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Thomas Hobbes: A Matter of Semantics. What better way to leave our homeport than with Aristotle, being hailed as “The Philosopher” for centuries, as our initial navigator. Aristotle made a distinction between the matter and the form of individual things. Loosely, matter is what an object is made of and form is the way in which this matter is organized. Both are inseparable, like the impression of a stamp in wax. Both are required to make a single, unified object: a heap of planks and nails is not yet a ship. Another Aristotelean distinction is between accidental and essential qualities. Objects can endure some qualitative changes but cannot persist through all. Some changes are ‘substantial’, involving the ceasing or coming-to-be of an object. A ship can survive a change of color but cannot survive dismemberment into a pile of planks, because its possession of a certain shape is integral to its form, and is implied by its being a certain kind of thing (a ship). A quality which an object can’t lose without ceasing-to-exist is an essential quality and the totality of essential qualities constitutes its essence. Clearly, there is a connection between the notion of form and essence and the form of an object seems to be ontologically more fundamental than its matter. And so, Aristotle would maintain that a ship can persist through a gradual change of planks without losing its identity, because its form stays the same even if its matter changes.
Aristotle’s distinction between matter and form somehow seems consistent with everyday communication. We don’t regard a ship as a mere aggregation of planks and the whole is somehow greater than the sum of the material parts. They must at least be arranged in a certain way before we can call it “a ship”. However, Aristotle’s ontology was rejected by most philosophers in the modern era. Speaking roughly, they rejected the distinction between matter and form as a way to explain natural phenomena. Relying only on the mathematical properties of matter, the explanation and prediction of nature’s behavior was much more successful. A frontrunner of this ‘mechanical philosophy of nature’ was the materialist Thomas Hobbes. But when it comes to questions regarding identity and individuation he still used the Aristotelian terms of matter and form (see: ????). But the innovative part of Hobbes’ thoughts, although he thinks that both matter and form play an important role, is that to treat them as exclusive solutions is a mistake!
Hobbes poses the question of identity over time and the beginning of individuation by asking “in what sense it may be conceived that a body is at one time the same, at another time not the same it was formerly”. He asks this with regard to flowing rivers, men growing old, evolving cities and then considers three possible solutions: “Some place individuality in the unity of matter; others in the unity of form; and one says it consists in the unity of the aggregate of all the [qualities] together.” Hobbes uses counter-examples to show that we run into problems if we use one of these exclusively. If we take matter "he that sins, and he that is punished, should not be the same man, by reason of the perpetual flux and change of man's body." He applies another counter-example to show the problems we encounter if we take form as the only solution: our ship of Theseus!
“…two bodies existing both at once, would be one and the same numerical body. For if, for example, that ship of Theseus, concerning the difference whereof made by continual reparation in taking out the old planks and putting in the new, the sophisters of Athens were wont to dispute, were, after all the planks were changed, the same numerical ship [the renovated] it were at the beginning; and if some man had kept the old planks as they were taken out, and by afterwards putting them together in the same order, had again made a ship [the reconstructed ship] of them, this without doubt, had also been the same numerical ship with that which was in the beginning; and so there would have been two ships numerically the same, which is absurd.”
Because of the absurd consequence of both ships being the same, Hobbes concludes that form alone cannot determine identity. Thirdly, he thinks that the aggregate of the qualities cannot determine identity because "nothing would be the same it was; so that a man standing would not be the same as he was sitting.”
But then, what does determine identity and individuation? Hobbes gives a ‘semantic’ solution:
“…we must consider by what name anything is called, when we inquire concerning the identity of it. For it is one thing to ask concerning Socrates, whether he be the same man, and another to ask whether he be the same body; for his body, when he is old, cannot be the same it was when he was an infant, by reason of the difference in magnitude; yet nevertheless he may be the same man.”
Hobbes distinguishes between a man and the body of a man and between the form and the matter of material things accordingly. And so we can ask different questions…but must also expect different answers then. If we ask questions about identity we should be clear-headed about what we mean. If, for example, we ask whether a river stays the same we should answer “no” if we mean whether the water in the river is the same; and “yes” if we mean with “river” that ‘thing’ through which water flows continually. If we ask whether the renovated ship in the harbor is the same as the original, we should answer “no” if we mean whether the planks are the same; and “yes” if we mean with “ship” that ‘thing’ which has gradually changed by the replacement of its planks. The opposite is true of the reconstructed ship in the warehouse. Hobbes’ ‘semantic’ solution is that matter and form should not be viewed as exclusive rivals. “Rather, each is a partial answer, correct if confined to its own proper domain, but inadequate when generalized.” Generalization will lead to paradoxes and contradictions. An important consequence of this solution is that identity not only depends on objective reality but also on the subject asking particular questions about it.
Where does this leave us on our journey? Having left our homeport with Aristotle as our navigator, Hobbes advises us to be specific about the meaning of our questions. Only then we can set sail to non-contradictory destinations. Is Hobbes right? Let’s ask another travelling-companion.
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Jonathan Lowe: Keeping Up Appearances. An alternative solution is presented by Jonathan Lowe in his book “A Survey of Metaphysics” (2002) and boils down to the conclusion that the reconstructed ship in the warehouse is not Theseus’ ship, but would have been if the planks of the original ship in the harbor had not been replaced. If, on the other hand, we would feel attracted to one of two more radical solutions, we have to give up on commonsense according to Lowe:
“[W]e are in no position simply to stipulate that one and the same thing can exist in two places at once, or that two different things can exist in the same place at the same time: if we want to say that either possibility obtains, then we must earn the right to do so by advancing cogent arguments – and that may not prove to be at all easy.” (Lowe, 2002; 29-30).
Lowe’s worries about these more radical solutions seem plausible. He regards his own solution as more satisfying because “our common-sense conception of objects and their persistence can escape altogether unscathed from the puzzle of the ship of Theseus, if we handle it with due care”. Sounds promising! But how cogent and commonsensical are Lowe’s arguments?
Lowe makes a distinction between a no-renovation-case in which an artifact, like a ship, is disassembled and later reassembled, and a renovation-case in which the original parts are replaced. In the no-renovation-case “it seems proper to say that the ship in question has a full complement of parts, but half of them are in the warehouse and half of them are still in the partially dismantled ship” (Lowe, 2002; 30). But in the renovation-case the original parts have been replaced by new ones in the harbor. Clearly, we have one entire and functioning ship in the harbor. Lowe now asks if
“we also have, at that time, a ship with a full complement of parts, half of which are in the warehouse and half of which are in the harbor? If we answer “Yes”, then we must say, it seems, that half of these parts are shared by two distinct ships, namely, the half which are in the harbor. The ships in question must be distinct ships, because they do not have exactly the same parts – one of them has parts all of which are in the harbor, while the other has half of its parts in the harbor and half in the warehouse” (Lowe, 2002; 30).
And now commonsense makes its decisive entrance in Lowe’s argumentation:
“[I]t is very doubtful that it makes sense to say that two distinct ships can, at the same time, share half of their parts. Certainly, our common-sense conception of objects and their persistence does not license us to say this. I suggest, then, that we should not say this. But then we must decide to which ship the various parts concerned belong at the time in question” (Lowe, 2002; 30-31).
Following his concern for commonsense, the fact that all of the parts in the harbor belong to the ship that is in the harbor and his suggestion that none of these parts simultaneously belong to another ship, Lowe concludes that:
“there is no ship which has a full complement of parts half of which are in the harbor and half of which are in the storehouse [and thus] that the parts in the warehouse belong to no ship at all at that time. This is quite different from what we say about the parts in the warehouse in an ordinary case of disassembly and reassembly” (Lowe, 2002; 31).
Again, Lowe’s solution boils down to the conclusion that the reconstructed ship in the warehouse is not Theseus’ ship, but would have been if the planks of the original ship in the harbor had not been replaced. Lowe, although not referring to Aristotelian concepts himself, essentially claims that in cases where form and matter conflict, form takes priority over matter as a criterion for numerical identity. If there is no conflict, either criterion is potentially adequate.
In my opinion Lowe’s solution has two weaknesses. First, it violates the intuition that whether a and b are identical can only depend on a and b and not on the existence of something else. Lowe gives reasons why he thinks this is not the case, on the premise that in the two situations “the reconstructed ship” would be a different ship with different referents. However, the parts of the reconstructed ship in both cases are qualitatively identical, so how the difference in numerical identity of the whole obtains remains problematic. It is difficult to see what is objectively different between the reconstructed ships in both cases. The second weakness, though insightful, is that Lowe’s solution depends on his own suggestions and ideas of commonsense. “Once the original parts of a ship have been appropriated by another, distinct ship, I suggest, they cease to be parts of the original ship” (Lowe, 2002; 31). Lowe’s solution rests entirely upon agreement with this principle and not upon anything more concrete than that. An archeologist who wants to determine the age of Theseus’ ship should certainly not go to the harbor to retrieve planks for carbon-dating. Regardless of whether or not the removed planks have been reassembled, she should go to the warehouse. A sailor however should go to the harbor. What is underlined by this is an issue of context that is overlooked by solutions presupposing identity as something objectively real. The sailor and architect will never agree which ship is identical with Theseus’ ship. Both embrace different criteria and neither is able to offer sufficient evidence for the superiority of either criteria.
Where does this leave us on our journey? While Hobbes seemed to point to the semantic-subjective nature of identity, Lowe is keeping up appearances. He wants to uphold our commonsense view on identity as being something objectively real, by making arbitrary suggestions. Yet he also admits that “it would be foolish to suppose that one’s person’s solution will necessarily convince everyone else” (Lowe, 2002; 40). And indeed, our next travelling-companion already showed a skeptical attitude when he saw Lowe using commonsense as his compass.
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Nagasena: Vanishing into Nothingness. Before we started our journey, Nagasena tried to convince Milinda he was not a distinct person and that the name “Nagasena” was just a convenient designator. The same holds, Nagasena thinks, for all material objects, like chariots. But doesn’t our paradox disappear if the “ship of Theseus” is also just a convenient designator, not referring to any really existing object persisting through time? All along the real existence of Theseus’s ship was an unquestioned, although hidden, premise. Could it be false? This ‘solution’ contradicts our commonsense view of reality completely! What are Nagasena’s arguments?
Initially Milinda is shocked by Nagasena’s claim that a name is only a useful way of labelling something that is not really a person. How is it possible, if there are no persons, there are individuals who give food to individual monks; or individuals irresponsibly committing evil deeds? Indeed, that seems impossible but these absurdities follow, Milinda thinks, from Nagasena´s claim. Milinda anxiously asks if some bodily part couldn’t be identified as Nagasena? What about the whole body or feelings, perception, volition or consciousness? Maybe all of these things together or something outside of them? Nagasena tenaciously answers “no” in each case. Milinda concludes that “Nagasena” is a mere empty sound, leading to the mentioned absurdities.
However, Nagasena tries to convince Milinda there is a difference between a name being a mere empty sound and being a convenient designator. He applies Milinda’s own questioning and reasoning to the word “chariot”. Nagasena asks if the chariot can be identified with some of the individual parts, the unity of the parts or something outside this unity. Milinda also answers “no” in each case. Nagasena concludes, somewhat sarcastically:
“King Milinda here says thus: “I came in a chariot”, and being requested, “Your majesty, if you came in a chariot, tell me what the chariot is,” he fails to produce any chariot. Is it possible, pray, for me to assent to what he says?” (Siderits, 2007; 53)
Surprisingly fast Milinda admits that the word “chariot” is not a mere empty sound, but a convenient designator and a useful way to refer to the parts being put together in a certain way. The same applies, Nagasena says, to persons. And so it seems that the chariot is not actually a real thing. The parts are real but the whole that consists of these parts is not. The whole can be reduced to the parts but isn’t something over and above them. This view is known as mereological reductionism. But why then do we consider the whole as one really-existing object when the parts are organized in a certain way and not when ‘its’ parts are scattered around or put together arbitrarily?
The difference in our ontological attitude (thinking of them as one thing in the one case but as many things in the other) stems from the fact that we have a single word for the parts in the first case but not in the second. And why do we have this single word in the one case? Because we have an interest in the parts when they are arranged in that way. When the set of parts is arranged in the assembled-chariot way, they serve our need for a means of transportation.” (Siderits, 2007; 55)
It somehow makes sense to say that we describe reality according to our interests. We have a single word for a collection of matter if it serves our convenience. But how does this show that a chariot isn’t really real? The answer is that “we shouldn’t let our interests dictate what we take reality to be like” (Siderits, 2007; 55). It suits our interest and it’s convenient to designate a collection of planks organized in a certain manner as “ship” if we can use it to sail the oceans. And it’s convenient to designate this collection of planks as “ship of Theseus” if it has been used by Theseus to sail the oceans. “Ship of Theseus” is a convenient designator that serves our interests but it’s a mistake to project our interests and convenient designators onto reality as really-existing single objects with unchanging identities persisting through time. The “ship of Theseus” is not an empty sound; it does refer to something, but not to what it appears to refer to. “Its reference is misleading, for it seems to be the name of a single thing, [a ship], and there really is no such thing.” (Siderits, 2007; 55)
Where does this leave us on our journey? Lowe wanted to keep up appearances by maintaining our commonsense view on identity as something objectively real. Hobbes, although still referring to
objective reality, pointed to the semantic-subjective nature of identity. Going even further, Nagasena considers Theseus’ ship as not ultimately real but nonetheless accepted as real by commonsense. Nagasena seemingly claims that an important but hidden premise, considering the real existence of Theseus’ ship, is false. Theseus’ ship vanishes into nothingness; the paradox following in its wake…
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Evaluating Our Journey, Sailing Forever…I regard Hobbes and especially Nagasena as our most credible travelling-companions. I think that solutions that proclaim an objective fact-of-the-matter regarding identity quickly lead to contradictions. It’s a mistake to view numerical identity as something objectively real, rather than as an (inter)subjective concept that we project upon the world. To see identity as something intrinsic, rather than conceptual, necessitates paradoxes. Lowe’s solution is applicable within his own conceptual framework but also exemplary for the misunderstanding that causes the paradox: that identity is purely objective, discovered by us rather than determined by us. And so, my main conclusion is that there is no definite solution to the paradox as long as we posit an objective fact-of-the-matter regarding numerical identity. The paradox will disappear once we realize that there are no sharp and clear-cut boundaries in a fluid reality that determine the identity of separate existing ‘things’ persisting through time, although commonsense suggests otherwise.
Some say that the journey is more important than the destination. Very well, this must certainly be true of the ship of Theseus because there simply is no destination. We can only observe its paradoxical journey on the vast oceans of thought, seeing it slowly vanish into nothingness. Like “the Flying Dutchman” it is doomed to sail the oceans forever never dropping anchor. But it left us with a fundamental metaphysical insight and also taught us something about ourselves. Thanks to a critical assessment of the paradox we came to the conclusion that our concepts are merely convenient designators, merely human and useful conventional inventions. And thus, in the best sense of the words, fictions and illusions! Admittedly, though, it took some long and hard thinking to arrive at and accept such a non-commonsensical conclusion, a little twisting and turning of the rigid and rusty mind, trying to ‘solve’ seemingly unsolvable paradoxes along the way. But it might take a Royalty to understand and accept such a conclusion as quick and cheerfully as King Milinda did.