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When is a remade object considered the same object as the original?
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metaphysics
Detail of a Roman copy (2nd century bce) of a Greek alabaster portrait bust of Aristotle (c. 325 bce); in the collection of the Museo Nazionale Romano, Rome.
In metaphysics, determining whether a remade object is the same as the original involves navigating the distinction between descriptive identity (being an exact duplicate) and numerical identity (being one and the same thing).123
This problem is famously illustrated by the Ship of Theseus, which questions whether an object remains the same if its parts are gradually replaced or if those original parts are later reassembled. Philosophers offer various perspectives:1
- Persistence and Parts: Some argue that an object persists through time by having temporal parts, while others maintain that an object is "wholly present" at each moment of its existence.4
- Relative Identity: Philosopher Peter Geach proposed that numerical identity is not absolute but relative to a "sortal" term (e.g., "is the same ship as"). Under this view, a remade object might be considered the "same ship" as the original, even if it is not the "same material thing".12
Ultimately, any solution must remain consistent with Leibniz’s law, which states that if two things are numerically identical, they must share all the same properties.12