Urban Identity through Time
Cities, Civilizations, and the Ship of Theseus Paradox
Cities are living illustrations of the Ship of Theseus paradox in so far as cities retain their identity despite change, even when this change approaches or even achieves totality. A city like Tokyo looks nothing like it appeared a hundred years ago, as almost every building has been replaced, but we say that it is still the same city. A city at one point in time in its history can be composed of different persons, buildings, streets, etc., as compared to the same city at another time in its history, and we still think of it as the same city, presumably due to its spatio-temporal continuity. Though, as we shall see, spatio-temporal continuity is not necessarily the whole story.
What is the relationship between urban change and the ship of Theseus? Here is how Plutarch described the Ship of Theseus problem:
“The ship wherein Theseus and the youth of Athens returned [from Crete] 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, “Theseus”)
Here is Hobbes’ statement of the paradox, with an additional twist:
“…if for example, that ship of Theseus, concerning the difference whereof made by continual reparation in taking out the old planks and putting in new, the sophisters of Athens were wont to dispute, were, after all the planks were changed, the same numerical ship it was at the beginning; and if some man had kept the old planks as they were taken out, and by putting them afterwards together in the same order, had again made a ship of them, this, without doubt, had also been the same numerical ship with that which was at the beginning; and so there would have been two ships numerically the same, which is absurd.” (Hobbes, De Corpore, 2, 11, 7)
If, in these passages, we were to substitute buildings for planks, we would have a rough description of the way in which cities change over time. At the Bokrijk open air museum in Belgium, there is a section devoted to historical structures that formerly stood in Antwerp (at least, there was when I visited in 1990; things may have changed in thirty years). If a block of Antwerp were to be exhaustively reconstructed from original materials at Bokrijk, then we get the ship of Theseus with the Hobbesian coda: there would be two blocks of Antwerp that were numerically identical, and that, as Hobbes noted, is absurd.
A difference to note between the Hobbesian formulation of the paradox for entities like ships and for entities like cities is that cities are uniquely associated with a particular geography. Even if we tore down all the buildings of Antwerp and reconstructed them elsewhere, we would not say this was Antwerp because Antwerp is a city that inhabits a particular geographical locale.
But suppose we reconstruct historical Antwerp elsewhere from where Antwerp stands, and then modern Antwerp is destroyed by some cataclysm. Then we take the displaced historical structures and reconstruct them at the former geographical location of Antwerp. Would this be Antwerp? Would this be Antwerp reconstructed, or would it be a facsimile of Antwerp, a mere copy, a knock-off city, as it were? This is something like a reconstituted city, with “reconstitution” understood as I discussed it in When Civilizations Go Underground and Civilization: Recovery, Reconstitution, and Reconstruction.
There are also exceptions to a strict rule of associating a given city with a specific geographical locale. An interesting example of a thorough rational reconstruction of a city in classical antiquity is the history of Knidos, where the ancient population rebuilt a grander city at a slightly offset location from its previous location. Paradoxes could be generated from elaborating this state-of-affairs, by supposing that a city is moved, and then moved back again to its original location. Which is the “true” city, the one at the first location, or the one at the second location?
If we consider a city to be its people and its institutions (or the continuity of a people and its traditions), whereas its corporeal expression is a contingent property subject to change over time, then the Jujuy Exodus during the Argentine War of Independence, in which the people of Jujuy Province in Argentina evacuated en masse, then the city of San Salvador de Jujuy ceased to be that city when its people deserted the streets and buildings of the city, and only became the same city again when the population returned. (I had the good fortune to be in Argentina for the bicentennial of their war of independence, and I was in San Salvador de Jujuy for a re-enactment of the Jujuy Exodus, which was reported in the local newspaper in the largest type I’d ever seen for a headline.)
There are several ways to expand upon this paradox. Given that a civilization is a network of cities bound by relations of cooperation, competition, and conflict (one of eight definitions of civilization that I employ, and which I call the pragmatic definition of civilization), we can reconstruct the paradox of the ship of Theseus at the level of civilization by observing that a civilization might at time t-0 be constituted by cities A, B, and C, while later, at time t-1, the same civilization would be constituted by cities D, E, and F.
If we wanted to further elaborate the paradox, we could note that these individual cities, A, B, and C, etc., may also be completely changed over time, so that even if city A, which once constituted an integral part of a given civilization, when it ceases to be a part of that civilization, is also completely changed so that it was, in at least one sense, no longer the city that it was when it was part of the given civilization. A city might cease to constitute an integral part of a given civilization by being destroyed, by being captured by the military forces of another civilization, by growing apart from the civilization of which it once was an integral part, and so on.
Another wrinkle in this was pointed out to me by Michael Goff, who noted the problem of Mexico City, which was Tenochtitlan up until the Spanish Conquest in 1521, and then Mexico City since then. Is this the same city? Does the imposition of Spanish rule and Spanish institutions mean the end of Tenochtitlan, even if the native population remained largely unchanged?
In the particular case of Tenochtitlan/Mexico City, I am reminded of Nelson Goodman’s grue paradox, which is intended to point out problems with inductive reasoning rather than problems with identity over time (hence it is also known as the new riddle of induction). Goodman formulated the Grue paradox as follows:
“Now let me introduce another predicate less familiar than ‘green.’ It is the predicate ‘grue’ and it applies to all things examined before t just in case they are green but to other things just in case they are blue. Then at time t we have, for each evidence statement asserting that a given emerald is green, a parallel evidence statement asserting that that emerald is grue. And the statements that emerald a is grue, that emerald b is grue, and so on, will each confirm the general hypothesis that all emeralds are grue. Thus according to our definition, the prediction that all emeralds subsequently examined will be green and the prediction that all will be grue are alike confirmed by evidence statements describing the same observations. But if an emerald subsequently examined is grue, it is blue and hence not green. Thus although we are well aware which of the two incompatible predictions is genuinely confirmed, they are equally well confirmed according to our present definition.”
When applied to natural kinds like emeralds and rubies the Grue paradox has always struck me as implausible unrealistic, but when applied to human history, as, for example, to the rapid change from Tenochtitlan to Mexico City, it does not seem implausible at all. Parallel to Goodman’s formulation of the Grue paradox, we could say that city x is Tenochtitlan up to 1521 and Mexico City after 1521, but this would only take us deeper into the heart of yet more paradoxes. At time t we have, for each evidence statement asserting that a given city is Tenochtitlan, a parallel evidence statement asserting that that city is Mexico City.
This problem of sudden changes to the identity of a city also can be extrapolated from the scale of a city to the scale of a civilization. Let us once again consider the Spanish Conquest of Mexico by Cortez (though we could equally well consider the Spanish conquest of Peru by Pizarro, or the Turkish conquest of Constantinople by Mehmet the Conqueror). Upon the conclusion of the Spanish conquest, a network of cities previously ruled by the Aztecs were now ruled by the Spanish. In this way, Aztec civilization came to a sudden end, and a new Spanish colonial civilization suddenly came into being, despite the fact that the majority population of Mesoamerican remained the native peoples, the infrastructure they inhabited remained largely the same, the lived experience of the peoples was largely the same, and so on.
Over time, Spanish rule of Mesoamerica changed the institutions of ordinary life, though those institutions that were predicated upon the raising of staple crops — namely, the “three sisters,” maize, squash, and beans — necessarily remained in place, or starvation would have ensued. Presumably, the overlay of Spanish colonial institutions eventually changed the significance of agricultural institutions, but we know that many native institutions remained present in what I call a submerged form.
In any case, there is a sense in which we can say that the civilization of Mesoamerica was Aztec up to 1521, and after 1521 the civilization of Mesoamerica was Spanish America. Is this a paradox for civilization? Maybe yes, and maybe no. But whether it is merely strange, or paradoxical, or an outright contradiction (like Hobbes noting that two ships might be counted as numerically the same), I see these paradoxes as a way to probe the concept of civilization and we can probably learn something both about civilization and our conceptual framework that we bring to thinking about civilization.
In the far future of human civilization, if we are willing and able to escape the evolutionary dead end that is planetary endemism, we may wish to reconstruct our historical cities in some stable, artificial environment where they will not be subject to the vagaries of plate tectonics, and where they can endure as long as their building materials last. We may yet, then, be presented with even stronger forms of these paradoxes.
