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Ship of Theseus

How Random Babbling Becomes Corporate Policy

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Mad science gone horribly, horribly wrong(or right).

Ship of Theseus

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The Ship of Theseus is one of those old philosophical saws. It came up in conversation the other day, and so I skimmed the Wikipedia article, only to be surprised that none of the sources cited took the same attack to the problem that seemed intuitive to me.

So, on the off chance this is a relatively original idea, I decided that I should get it written up.

For those unfamiliar, the Ship of Theseus poses this problem: If you take a ship, and replace every component of the ship, until nothing original remains, is it the same ship? At what point does it cease to be the same ship?

Common sense tells us, of course, that it is the same ship. And everyone from Aristotle forward has tried to explain why that is, with the occasional jerk that takes the stance that it isn't the same ship.

The Aristotelian approach was to separate the formal cause and the material cause of the thing. It's a fairly Platonic approach, which isn't surprising: there's the "idea" of the ship, and the "material" of the ship- even as the material changes, the idea stays the same. Pirsig's concept of patterns is a less Platonic approach to the same idea: there's the pattern of a ship which is made up of subpatterns in the form of the different components; changes to the subpatterns don't change the over-pattern.

The other big approach is "four dimensionalism"- which, at first glance, was my preferred approach to the subject. If you view the ship not as a three dimensional object, but a four dimensional one, where its history and future are one long line, and the 3D ship is just one temporal slice out of that line, you can easily resolve this conundrum.

Except, of course, that to be complete, one would have to have a 4D timeline for all of the components, and suddenly the ship is less a ship, than a generalized area where the timelines for other objects occasionally merge.

I'm not a fan of any of these approaches, in part because they all share an unspoken assumption: that the world is composed of objects, and that these objects are distinct from one another.

Our sense organs receive inputs from the world, a whole hierarchy of processing centers pick up those signals and organize them into structures. When you look at the pathway of just the visual processing centers, you can clearly see the evolutionary steps that built the rather complex visual system we have. At low levels, we have simple abilities like recognizing lines, and increasingly complex abstractions get built up from what is, at the lowest level, the stimulation of light sensitive cells.

Photons excite your rods and cones, which in turn send signals across your nervous system, which get processed by various neurological systems and result in a mental model of the world, where those photons are interpreted as "a ship".

A large purpose of our brains is to convert the inputs to our senses into models that can be manipulated and acted upon. If my brain is able to identify that ship as Theseus's ship, and not my ship, I know not to trespass, less I earn myself an ass-kicking. And by being able to distinguish those sensory impressions as "a ship" and not, "ocean", I can do nifty things like not drown because I thought I was standing on a boat's deck while really I'm on the ocean floor.

It sounds absurd, but we know that, when failures occur in this processing system, really bizarre results can occur. Like the rather famous story of a man who thought his wife was a hat.

The point I'm trying to dig down to is this: the world is not a collection of objects that we can interact with. The world is continuous. The identity of objects as distinct objects is not a fact of the world, but a fact about our understanding of the world. The pile of matter that constitutes Theseus's ship is just a pile of matter.

The problem of Theseus's ship is not one of the identity of objects: objects don't have an identity. The identity of objects is a perceptual thing, born from our own minds' organizing principle. Our brains are object oriented. The world can be understood in these terms, but as the Ship of Theseus problem shows, there are edge cases that can give us bizarre results when we start trying to analyze what about an object provides it with its identity.

God, I hope that made sense.
  • Makes perfect sense to me. The only thing I'd add is that you talk about the outside observer's object orientedness. I'd say that many things in the universe that do not have the capacity to understand or philosophize are still object-oriented.

    For example, take a shipworm, which devours wooden hulls. The wood that it bores into and consumes is really nothing more than a transient, local pattern in the cosmic stuff (just because I can't remember the names of the phenomena, don't assume I'm going mystical on ya!)

    But that pattern being wood (and a particular kind and condition of wood) is essential to the shipworm's getting its home and dinner. The shipworm doesn't conceptualize ships or woodenness, but neither does its lack of concepts render it capable of making do with some other arrangement of subatomic bits and bobs.

    Maybe that's just a matter of scale. Shipworms and ships are on the same scale (things big enough and slow enough that Newtonian physics is reasonably accurate at making predictions) so they are "real" objects to each other, and the four dimensional model has a certain utility for describing them.

    • A shipworm is a cognitive entity, albeit one with very different capacity from a human. Whether or not it's actually building an object oriented model of its environment is something I don't think we could really discuss without a serious investigation into termite intelligence. But it is definitely a modeling entity. Just like a human builds a model of the outside world, a shipworm has the capacity to build an internal model of the outside world. The vocabulary is certainly different, and so are the priorities.

      I'd argue that it probably isn't object oriented, as much as a reactive system, aware of organizing events and inputs in terms of preferences. If you think about it, a shipworm's experience on Theseus's ship is one of an environment where the food supply is constantly replenished. The board it was eating yesterday is replaced by a new one. One day, the board it's sleeping in is replaced, and used for firewood, and the shipworm's world ends. The discussion of, "is this the same ship" is utterly without meaning to an intelligence focused on being a shipworm.

      But I do agree, that being able to build an object model of the world and being able to philosophize are two very different things.
  • Oh! I didn't know it had an official name... in my family, we usually use the example of "my grandfather's hammer" which had the handle replaced three times and the head replaced twice but it's still the same hammer.

    (I think the grandfather in question is my dad's dad's dad... possibly even my dad's biological dad's dad, but it really could be anyone's grandfather. Or anyone's hammer. :P)
  • The same kind of thing applies to living organisms. We're all composed of millions of cells. Those cells die and are replaced by new cells. We're entirely composed of cells that did not exist a decade prior. Are we different people as a result? We aren't considered as such...
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