Once in my childhood, I remember doing a quiz named “Which philosopher are you?” For whatever reason, I got Heraclitus. I tried again because, at the time, I didn’t know who he was. I wanted to get someone more famous, but I got Heraclitus again. Since then, I’ve often used “Heraclitus” as a pseudonym on various sites. Partly because of this special relationship and partly because of my continuing fascination with obscurity, this essay will be about the obscure sage of Ephesus. More specifically, I want to explore Heraclitus’ idea of flux and its relation to the Ship of Theseus.
By changing it rests. (Heraclitus, Fragment LXXXIII)
You’re probably familiar with the Ship of Theseus, but for convenience, I’ll explain the main idea: Imagine a ship restored by gradually replacing each of its constituent parts. According to Plutarch, the philosophers later debated whether the resulting ship was still the original one. Thomas Hobbes later added another difficulty to the experiment: imagine that from the old parts, we assemble another ship (Hobbes, 1656, p. 100). The two are certainly not the same, yet you could reasonably claim that either of these is the original ship. One ship is the same as the original by one set of criteria. Another one is the same as the original ship by another set of criteria. So the main questions are: At what point does the ship lose its identity? What criteria should we use for determining whether X is still X after experiencing changes? Which ship, if either, can correctly be called the same as the original one?
The ship wherein Theseus and the youth of Athens returned had thirty oars, and was preserved by the Athenians down even to the time of Demetrius Phalereus, for they took away the old planks as they decayed, putting in new and stronger timber in their place, insomuch that this ship became a standing example among the philosophers, for the logical question of things that grow; one side holding that the ship remained the same, and the other contending that it was not the same. (Plutarch, Life of Theseus)

Now let’s consider Heraclitus. His thoughts come to us, unfortunately, only in the form of fragments. But it’s common to assume that there was a coherent, continuous text in the beginning. Nietzsche questioned this assumption, but I’ll leave that debate aside. It is, therefore, the job of philosophers and historians to construct a coherent picture of Heraclitus’ doctrine. This is an extremely difficult, if not impossible, task. Primarily because of the epigrammatic and enigmatic nature of the fragments. He was often called “the obscure” for this exact reason (Brémond, 2019). His legacy is the opposite of La Bruyère’s. Where La Bruyère is today mostly ignored because of his clearness and moderation (Barthes, 1964/1972, p. 222), Heraclitus continues to arouse interest, not despite but because of his cryptic language.
Generally speaking, that which is written should be easy to read or easy to utter, which is the same thing. Now, this is not the case when there is a number of connecting particles, or when the punctuation is hard, as in the writings of Heraclitus. For it is hard, since it is uncertain to which word another belongs, whether to that which follows or that which precedes; for instance, at the beginning of his composition he says: “Of this reason [Logos] which exists always men are ignorant,” where it is uncertain whether “always” should go with “which exists” or with “are ignorant.” (Aristotle, Rhetoric, Book III, chapter 5, section 6)
At the beginning of his book, which is quoted above by Aristotle, Heraclitus speaks of the Logos (λόγος) and later tells us that in the book, he will explain how everything relates to everything else, distinguishing each thing from others. But in what follows, Heraclitus tells us, again and again, that everything is the same. So from the beginning, Heraclitus speaks paradoxically.
Today, Heraclitus is primarily known for three doctrines: (1) universal flux, (2) the unity of opposites, and (3) fire as the primary material of the world (Graham, 2021). The latter doesn’t concern me here. I will therefore focus on the former two. The interpretations of those first two doctrines are, as with any obscure writer, controversial and open to debate.

You could not step twice into the same rivers; for other waters are ever flowing on to you. (Heraclitus, Fragment XLI)
For Heraclitus, the river has an identity even if the flowing water is always different. The Ship of Theseus retains its identity even when it is constantly changed. You are the same person you were a year ago, no matter how dramatically you’ve changed. Heraclitus makes Logos responsible for this strange harmony behind the flux and makes understanding this Logos the primary aim of his inquiry. As Hans-Georg Gadamer claims, Heraclitus didn’t just believe in flux. He was more interested in the paradox of something changing yet retaining its identity.
… the pieces, the substances, the materials change, to the point where the object is periodically new, and yet the name, i.e., the being of this object, remains always the same; it is therefore a question of systems rather than of objects … (Barthes, 1964/1972, p. 153)
Merely stating that the river has a certain unity is no proof of said unity. One way we could interpret this is to say that Heraclitus believes that the name determines identity. So if we still call it the Ship of Theseus, that’s what it is. If others see you as the same person, then you are. I suspect Wittgenstein would subscribe to this view. He would claim that there is no objective identity of things. It’s only a matter of how we use language. But it’s not clear to me whether this is what Heraclitus believes.
Into the same rivers we step and do not step; we are and we are not. (Heraclitus, Fragment LXXXI)
Heraclitus is pointing out the paradox. He’s not interested in providing a clear solution. As with any philosophical question, no one can give a conclusive answer. Expecting to find one is naive. That is not the point of Heraclitus’ book. And it’s not the point of this essay. The Ship of Theseus is still a puzzle on which philosophers don’t universally agree. Some think spatio-temporal continuity should be privileged over the concept of identity retention through change, thereby claiming that the ship assembled from the original parts has a stronger claim to being the original one. Others think the opposite. There are many elaborate arguments involving possible worlds, but I won’t get into that here (e.g., Kripke, 1980).
Let’s consider another relevant fragment from Heraclitus about the ancient Greek drink called the posset. It is a mixture of “wine, barley groats, cheese, and herbs or drugs which remain suspended only if they are continuously stirred” (MacKenzie, 1986). If you stop stirring, the solids will sink to the bottom. What you will drink won’t be the posset. So for the posset to retain its identity, it must move. Change and motion can, therefore, be a necessary condition of identity, not a hindrance to it.
The posset too separates if it be not stirred. (Heraclitus, Fragment LXXXIV)
My aim was not to provide a solution to the problem of the Ship of Theseus but to infer how Heraclitus would have answered. And I believe we can formulate the general idea in the following way: The reassembled ship is still the original one because not considering it the original ship would undermine the way we ordinarily use language. We can also claim that the newly assembled one is the original ship. Yet we must understand that even those original parts constantly change due to being in different spatio-temporal circumstances. It, therefore, makes less sense to privilege the original parts over the new ones because those have also changed. So even if we didn’t replace any parts of the ship, that ship’s identity would still be questionable. Yet, for Heraclitus, it would be the same ship, and the fact of change would not touch the question of identity.
REFERENCES
- Aristotle. (1926). Rhetoric. In Aristotle in 23 Volumes, Vol. 22 (J. H. Freese. Trans.) Harvard University Press. http://www.perseus.tufts.edu/hopper/text?doc=Perseus:text:1999.01.0060
- Barthes, R. (1972). Critical Essays. Northwestern University Press. (Original work published 1964)
- Brémond, M. (2019). Les Présocratiques (A). dans Maxime Kristanek (Dir.), l’Encyclopédie Philosophique. https://encyclo-philo.fr/item/190
- Graham, D. W. (2021). Heraclitus. In E. N. Zalta (Ed.), The Stanford Encyclopedia of Philosophy (Summer 2021). Metaphysics Research Lab, Stanford University. https://plato.stanford.edu/archives/sum2021/entries/heraclitus/
- Heraclitus. (1931). On the Universe (W. H. S. Jones, Trans.). Harvard University Press. https://doi.org/10.4159/DLCL.heracleitus_philospher-universe.1931
- Hobbes, T. (1656). Elements of philosophy, the first section, concerning body. London : Printed by R & W Leybourn, for Andrew Crocke, at the Green Dragon in Pauls Church-yard. http://archive.org/details/b30335838
- Kripke, S. A. (1980). Naming and Necessity. Harvard University Press.
- MacKenzie, M. M. (1986). The Moving Posset Stands Still: Heraclitus Fr. 125. The American Journal of Philology, 107(4), 542–551. https://doi.org/10.2307/295102
- Plutarch. (n.d.). Life of Theseus (John Dryden, Trans.). http://classics.mit.edu/Plutarch/theseus.html