The Ship of Theseus
Stimulating critical thinking - a loose series on paradoxes
Gödel's is a newsletter about interweaving ideas and making decisions under uncertain conditions. I discuss knowledge management, mental models, and supporting Tools for Thought.
The Ship of Theseus paradox is a thought experiment that raises fundamental questions about identity and change, the concept of self, and the line we draw between what something is and what it becomes. Originating in ancient Greece, it is named after the mythical king Theseus of Athens, and over the centuries, it has become a fascinating standard through which philosophers and thinkers grapple with concepts like matter, substance, time, and metaphysics.
This paradox is typically presented in the following manner: suppose Theseus had a ship, a grand vessel known far and wide, preserved and displayed in the harbor as a historical artifact owing to its significant role in historical battles. Over time, due to wear and tear, the ship's wooden planks had to be replaced one by one. Eventually, after a long time, let’s say all the original parts of the boat were replaced. The question arises: is this renovated ship still the Ship of Theseus? Despite undergoing piece-by-piece replacement, it remains a ship, still floats on the water and bears the same name, but there’s not a single original piece from the time of Theseus. How can it be the same ship?
Intensifying the paradox, let's consider a twist to the original scenario. What if the thrown-away pieces were collected and used to build another ship identical to the original? Which one, then, is the genuine Ship of Theseus? One may argue that the original boat maintains its identity due to continuity and remains a ship all the time, in the same way, that one maintains identity from childhood to adulthood despite physical changes. One might argue that the reassembled ship assumes the original identity, as it is made entirely from the original materials, restoring the Ship of Theseus to its material wholeness.
The Ship of Theseus paradox has interesting implications far beyond the maritime world and extends into several contexts of modern reality, notably in biology and the human body. The human body continually undergoes a change process, with cells dying and new ones forming. It's estimated that about 50-70 billion cells die each day in an average human adult. Meanwhile, our bodies continually generate new cells to replace the old ones. Given this relentless cellular turnover, most cells are replaced every seven to ten years. Therefore, one could ask, are we still the same person we were seven or ten years ago? If identity adheres to our physical substance, we might not be.
However, like the Ship of Theseus, humans retain memories, personalities, and habits—cognitive and psychological continuities forming an individual's identity. While the wood from the Ship of Theseus was replaced, the ship's function and perception stayed constant, mirroring how humans, despite physical changes, maintain their identities through consistent consciousness.
The Ship of Theseus paradox leaves us with more questions than answers, reminding us of the complexities we overlook in identity and change. Despite its antique origins, it persists in contemporary conversations, playing influential roles in several philosophical, psychological, and scientific debates. Whether considering human identity or the identity of objects, the paradox demands to know: What makes something fundamentally what it is? Is it matter, continuity, or something else entirely? And though an answer seems elusive, the probing questions continue to shape our understanding of ourselves and the world around us.