Outer Limits of Reason by Noson S. Yanofsky Read Free Book Online Page B

change is gradual, does the ship still maintain its status as the ship of Theseus? How gradual must the change be?
    We are not answering these questions simply because there are no objective correct answers. Some maintain that changing one plank changes the ship and makes it no longer the ship of Theseus. Others claim that as long as there is at least one plank from the original, it is still the original. There are also those who maintain that the changed ship is always the same as the original ship because it has the form of the original. None of these different positions are wrong. However, there is no reason to say that any of them are correct either.
    Let us continue asking more questions about our beleaguered boat. What happens if we switch the old wooden planks for more modern plastic planks? Then, as we change more and more of the planks, the ship will be made of a different material than the original. What happens if the people who replace the planks make mistakes in putting in the new planks and the ship has a slightly different form? Another question: Does it matter who is making all these changes to the ship—that is, whether one group of workers does it or another? If the ship is to be preserved for hundreds of years, then surely many different people will have to be making the changes. What if we make so many changes to the boat that it can no longer float out to sea? Can we still call it the ship of mighty Theseus if it cannot perform the same function as the original? 2
    Such questions go on indefinitely. I will restrain myself and discuss just one more scenario. Imagine that every time a plank is changed, rather than consigning the old planks to the scrap heap, we store them in a warehouse. After some time, all the old planks are assembled into a ship. This new construction is made to look exactly like the old ship with the planks in their original position. Question: Which ship has the right to call itself the ship of Theseus, the ship with the replaced planks or the ship constructed out of the old planks?
    A common answer to some of these questions is that the ship remains the same because the changes are gradual. However, it is not clear why that should make a difference. How gradual must the changes be in order for the original ship to maintain its status? Is there a minimum speed limit for changes? To put the question of what is “gradual” in perspective, consider the case of Washington’s ax. A certain museum wanted to preserve the ax of the founding father of the United States. The ax consists of two parts: a handle and a head. As time went on, the wooden handle would rot and the metal head would rust. When needed, each of these two parts was replaced. As the years passed, the head was changed four times and the handle was replaced three times. Is it still Washington’s ax? Notice that here there is no question of the change being gradual. Every time a change is made, half the parts of the ax are replaced.
    Our discussion is not limited to ships and axes. A tree is lush and green in the summer and bare and brown during the winter. Mountains rise and fall. Cars and computers get refurbished. Any physical object changes over time. This is the content of Heraclitus’ famous dictum that you cannot step into the same river twice. For Heraclitus, the river changes at every instant.
    Physical objects are not the only things that change. Businesses, institutions, and organizations are also dynamic entities that constantly change and evolve. Barings Bank was in existence from 1762 through 1995. In that time, the owners, workers, and customers all changed. The Brooklyn Dodgers have been around since 1883. Their players, managers, owners, and fans have definitely changed. What remains the same about a baseball team? After heartlessly betraying their city of birth, the Dodgers cannot even claim that they play in the same city as they originally did. In colleges, the students change every