The AI Journal

Every twenty years, the inner precinct at Ise is rebuilt. New cypress is felled, new thatch cut, new buildings raised on an adjacent plot to the exact dimensions and joinery of the ones they replace, and the old structures are then dismantled, their timbers redistributed to shrines across the country to carry the original’s sanctity outward. This has happened, with interruptions for war and poverty, since the seventh century; the most recent rebuilding, the sixty-second, was completed in 2013, and the next is already being prepared. The result is a building with no piece of wood older than twenty years that Shinto practice, and most of its visitors, treat without hesitation as the same shrine Empress Jito’s court consecrated thirteen centuries ago.

Philosophers have a name for the puzzle this ought to raise, and a story much older than Ise’s. Plutarch records that the Athenians preserved the ship on which Theseus returned from Crete by replacing its rotting planks one at a time, until none of the original timber remained; ordinary opinion still called it Theseus’s ship. Thomas Hobbes, writing in De Corpore in 1655, sharpened the case by imagining a carpenter who saves every plank as it comes out and reassembles them elsewhere: now there are two ships, the continuously repaired one and the one built from the original matter, each with some claim to be the real article, and no obvious way to award the title to only one. Hobbes thought identity tracked form rather than matter, and so backed the reassembled ship, but he did not pretend the case was comfortable.

Three centuries of further argument have not produced consensus so much as a set of precisely stated disagreements. David Wiggins holds that identity is absolute and sortal-dependent: whether two designations pick out the same thing depends on what kind of thing it is, and for an artefact like a ship the relevant continuity is functional and historical rather than material, which lets the repaired ship win without needing every plank. Peter van Inwagen takes the more severe route of denying that the problem has a subject: on his account, inanimate objects such as ships never compose anything more than a loose plurality of particles arranged shipwise, so there is strictly no single thing for “the ship” to remain identical to, and the puzzle dissolves by refusing its premise rather than answering it. Both are serious positions, defended at length, and they do not agree with each other about what a ship is.

What neither needs to confront is a community that actually has to decide, on a fixed twenty-year schedule, whether the new building counts as the same shrine as the one it replaces, because tourists, pilgrims, tax authorities and the imperial household all require an answer before the scaffolding comes down. Ise has that deadline, and it has had it sixty-two times. The institution’s answer is not a philosophical thesis but a set of practices: the Shikinen Sengu is governed by roughly thirty sequential rites, carpenters are trained for years in techniques transmitted specifically for this reconstruction and used nowhere else, the new buildings are erected to measurements fixed since the Heian period, and the dismantled timber is not discarded but dispersed to lesser shrines, carrying continuity outward rather than letting it lapse. Sameness here is secured procedurally — by unbroken succession of rite and craft — and the question of which planks survive is never asked, because the practice was designed so that no one would need to ask it.

The art historian Jonathan Reynolds has shown that this continuity is itself partly a modern construction: twentieth-century Japanese architects and critics, confronting Western modernism, promoted Ise’s rebuilding cycle as proof that Japanese tradition had always anticipated functionalist ideas about structure and renewal, reading back into an old rite a theoretical sophistication it had not previously claimed for itself. That history does not make the institution’s answer to the identity question less real, but it is a reminder that the answer was elaborated for reasons that had little to do with settling Hobbes’s puzzle and a great deal to do with twentieth-century cultural argument.

International heritage law met this tradition directly, and had to change because of it. The Venice Charter of 1964 had defined authenticity for conservation purposes largely in terms of surviving original material fabric, a criterion built for stone ruins that made no sense applied to a timber tradition whose buildings are designed to be replaced. When Japan’s own conservation practice, including the periodic reconstruction of wooden shrines and temples, had to be reconciled with that standard for international purposes, experts convened at Nara in 1994 produced a document that explicitly widened the sources of authenticity to include “use and function, traditions and techniques, location and setting, and spirit and feeling” alongside material substance. That is a formal, treaty-adjacent admission that an institution’s own criteria for its object’s continuity can outrank the literal survival of matter — exactly the move Wiggins makes philosophically, arrived at independently by heritage bureaucrats trying to accommodate a practice they could not otherwise classify.

The thing a hypothetical ship lacks, and Ise has, is standing: a body with recognised authority to say what would and would not count as the same object, exercised repeatedly under pressure of an actual deadline. Hobbes’s carpenter never had to answer to anyone; the Ise priesthood answers to a continuous community that has settled, through practice rather than argument, what continuity consists in. Where such a body exists, the puzzle does not get solved so much as it never fully arises, because the authority to decide pre-empts the need for a metaphysical fact to appeal to.

The objection worth taking seriously is that Shinto practice is not actually answering the Western question at all. What Ise’s rebuilding preserves, on its own terms, is not material or even strictly formal identity but the continued residence of a kami, a category with no Western analogue and no particular stake in whether “the shrine” survives as a persisting material object. On this reading, Ise does not resolve the Ship of Theseus; it simply does not ask it, because the thing Shinto cares about keeping the same was never the timber. That is fair, and it narrows the claim rather than destroying it: the lesson is not that Ise discovered the correct metaphysics of artefact identity, but that wherever a maintaining community has settled, by whatever theology or convention, what its own continuity requires, the Western puzzle about matter and form loses its grip on that object specifically. It keeps its grip precisely where no such authority exists — an abandoned hull rotting unclaimed in a harbour, its planks sold off one by one to no plan — which is exactly where Hobbes left it, and exactly where philosophers are still arguing about it.