Theseus' ship

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The ship of Theseus (also Theseus paradox ) is a philosophical paradox that was already shown in antiquity . It touches on the question of whether an object loses its identity if many or even all of its individual parts are replaced one after the other.

Well-known scenarios of the paradox

Greek legend

The oldest formulation has been handed down by Plutarch :

“The ship on which Theseus set off with the young men and also safely returned, a galley with 30 oars, was kept by the Athenians until the time of Demetrios Phaleros . From time to time they removed old planks from it and replaced them with new, intact ones. The ship therefore became for the philosophers a constant illustration of the issue of further development; because some claimed that the boat was still the same, others, however, that it was no longer the same. "

The philosophical problem raised by this thought experiment is a widespread example in philosophy didactics and is also widely debated in contemporary ontology because there is a plausible theory about when an object can be considered one and the same and as such can persist even with changes in time , has to prove itself. Ted Sider, for example, defends that an ontological four-dimensionalism elegantly solves this problem. Four-dimensionalists take the view that objects, as they occupy sections in space, also do this for the time sections that are to be treated in the same way, that is, have “time slices” or can be imagined as “time worms”.

Duplicate Identity Problem

Another philosophical problem is that of double identity, which can be explained with a simple example:

“Theseus owns a somewhat older but seaworthy ship. One day he decides to take it to the shipyard and have it renewed there. He asks the shipyard owner to replace the 1000 planks with new ones. The owner of the shipyard owns several docks and thinks it is a shame to simply throw away the old planks of Theseus' ship, so he decides to gradually dismantle the Theseus ship in Dock A and have it replaced and to bring the planks to Dock B, where they are reassembled into a ship in the original order and in their original position, which works. "

Two ships now exist: the ship Theseus used and whose 1000 planks were replaced, and the shipyard owner's ship, which was assembled from all the original parts of Theseus' original ship. Which ship is Theseus' ship?

To do this, four different basic positions can be assumed:

  1. The ship from Dock A is Theseus' ship.
  2. The ship from Dock B is Theseus' ship.
  3. Both ships are Theseus' ships.
  4. Neither ship is Theseus' ship.

See also

Individual evidence

  1. ↑ Plutarch, Vita Thesei 23, translation by Wilhelm K. Essler, in: What is and what end does one operate metaphysics ?, Dialectica 49 (1995), 281-315
  2. ↑ Cf. on this and the following Jay F. Rosenberg: Das Schiff des Theseus. A case study , in: ders .: Philosophize. A manual for beginners , Vittorio Klostermann Verlag, 1993, chap. 4, p. 64 ff.

literature

  • Jay F. Rosenberg : The ship of Theseus - a case study, in: ders .: Philosophizing - A manual for beginners, Vittorio Klostermann Verlag 5. A. 2006, chap. 4, pp. 64-77. ISBN 978-3-465-04069-9
  • Christopher M. Brown: Aquinas and the Ship of Theseus. Solving Puzzles about Material Objects , London – New York: continuum 2005.
  • Theodore Sider : Four-dimensionalism. An Ontology of Persistence and Time , Oxford: OUP 2005, 4-10.145.

Web links

  • Ekkehard Martens: The ship of Theseus - integrative philosophizing with gifted children and young people between thinking training and happening, also in: ders .: Philosophy and Education: Contributions to Philosophy Didactics (Philosophy and Education Vol. 1), LIT Verlag Berlin-Hamburg-Münster 2005 , Pp. 253-263.
  • Harry Deutsch:  Relative Identity. In: Edward N. Zalta (Ed.): Stanford Encyclopedia of Philosophy . (Section 2.5; there is further literature on recent debates)