Goal:
investigate the following questions with students:
To what extent do objects persist over time despite changes to physical properties? To what extent does a person persist as the same person despite new experiences and changes to physical properties?
Materials
Play Doh
Cut up scenarios
Hat (or something else to hold pieces of paper)
Lesson Plan
35 min total
5 min: Make an object out of playdoh.
15 min: Discuss The Ship of Theseus
Part 1: A rich man owned a huge, beautiful wooden ship called the Theseus. He sailed it every week. One day a small wooden board on the right side started to rot, so the ship-builder replaced it with a new one. Several months later it needed a new steering-wheel. Several months later one board on the left side needed to be replaced. Several years later it needed a new mast. Eventually, after 50 years, he was still sailing the ship, but none of the original wood was in it – it had all been replaced piece by piece.
Ask students: Was it still the same ship? Why or why not?
Part 2: It turned out that the ship-builder was secretly keeping every piece of wood he removed. At the end of the 50 years, he had put them all together in exactly the same order, and even painted Theseus on the side. He launched the ship out into the harbor, next to the other one.
Ask students: Which one was the real Theseus? Why? When you think about this, think about whether you’ve changed your mind about your answer to the first question.
Key things to discuss:
Ownership (ship A, ship B)
Function (no longer functioning as a boat = not a boat)
Accidental properties/ essential properties
5 min: Crush your playdoh, and make something else. Is this the same object?
10 min: Pull scenarios about personal identity out of a hat and discuss.
Most of the cells that are in your body now weren’t there when you were a tiny baby. You grew lots of teeth and lost them, you grew lots of hair and had lots of haircuts, you ate lots of food and built new muscle and bone and tissue. Are you still the same person?
Imagine that someone takes your brain out of your body and places it into a different body. An evil scientist forces you to shock one of the 2 bodies, do you choose to shock the body that your brain was placed into or the body that used to belong to you?
If you can easily find a photo of you as a baby, find it! Are you the same person that you were in the picture? What about you has stayed the same?
Who would you be if all of your physical properties disappeared? Who would you be if all of your mental properties disappeared? Is one more important to your identity?
What if your parents had accidentally swapped you with your twin when you were infants. Who are you?