Ship Of Theseus Essay

The ship of theseus is a thought experiment used to show the nature of identity. Ship A leaves harbor with a hull full of parts identical to every part on Ship A. When at sea, the men on the ship start to replace every piece of Ship A with the identical parts from the hull. They continue until every piece of wood and every bolt has been exchanged. The ship that is comprised of the new identical parts is Ship B. When the ship is brought back to harbor the men construct a new ship with parts left over, this is Ship C.

There are two ways in which two things can be considered identical. They can be numerically or qualitatively identical. Objects are numerically identical if and only if every peice of those objects are one in the same (Handout #6). Objects are qualitatively identical if and only if they share all of the same properties. (Handout #6) To the townspeople, Ship A and Ship B would seem to be numerically identical. They saw Ship A leave port, and saw an identical Ship return. But for the Ships to be numerically identical they must be one in the same. Which means that Ship A and B must occupy the exact same space at the same time. We know this is not true

The Ship of Theseus shows how materialist theories fail to explain how things can change throughout time yet still be identical. Leibniz’s Law states that “x and y are identical (i.e., x=y), then x and y have the same properties (for every x and y),” (Dolson, HO #3, p.1). When a person ages, their bodies change. The person will have different memories, they will have grow bigger, the way they respond to situations will change. For a materialist theory to say that a person at age 6 is the same person at age 60, they must reject Leibniz’s Law. Leibniz’s Law requires that for a person at age 6 to be the same person at 60 they must share all of the same properties, which is clearly not the