This went on for a few years until eventually it was entirely made of metal.

Every time a piece of the ship needed replacing it was replaced with a metal part. Theseus owned a ship and the ship was entirely made of wood. For example, if someone says that it would be the new ship when more than half the parts are replaced, test it: so are you saying that it is a new ship when it has 51 metal parts and only 49 wooden ones? Then ask everyone what they think about this. You can then use this at each point of the discussion to have them explore and reach the difficulties for themselves. I would ask the children to imagine that the ship has 100 parts. If not, then when does it become the new ship? This particular problem is known as the sorities paradox (from the Greek word for ‘heap’): how many grains of sand make a heap?įor the purposes of keeping things clear for the discussion it is a good idea to illustrate all this with examples as you go. If it is a new ship when the parts are all replaced and only then, would that mean that when it only had one part left to replace, it was still the old ship? If so, this seems a little odd. The embedded question to bear in mind in this whole discussion is if it is a new ship when all the parts are replaced then at what point does it become a new ship? This is where a lot of the philosophy will lie because here we are faced with the ‘problem of vagueness’.

In order for this session to be philosophically fruitful it is necessary to understand the philosophical subtleties involved in an exploration of the thought experiment.

This example was famously supplied as a philosophical thought experiment by Thomas Hobbes, the British philosopher of the English civil war, into which he was born (he said that he was born twins with fear), but he drew the example from Plutarch, a Roman writer, and, of course, Theseus comes from Greek mythology. This extension to the session already in the book helps to make the exercise visual and kinesthetic so that other learning styles in addition to the auditory can be accommodated. Invite the group to come up and use the model to demonstrate their ideas for the benefit of everyone in the group. As you explain the process of gradual change replace each pencil with another pencil creating a pile of the discarded pencils to one side of the ship. When doing The Ship of Theseus chapter from The If Machine make the puzzle visual by assembling a model of the ship on the floor with some identical pencils and a piece of paper for the sail.

Homm vii can't get on ship