Saturday, February 07, 2009

The Ship Theseus

Ray North was an International Master Criminal who had the reputation of getting his job done. His latest client had ordered him to steal the famous ship Theseus, from which the British Newspaper magnate Lucas Grub had thrown himself into the arms of death and had been the scene of murder of a famous LA rapper. Above all it had historical significances associated with it that made it worth millions of dollars. But Ray was now dubiously standing at the dock where the ship had just been repaired, confronted by a dilemma he didn't know how to resolve. There were two seemingly identical ships standing in front of him. He held the security man at gunpoint and bellowed, "If you want to live, better tell me which one of these is the real Theseus!"

The man nervously swallowed and said, "That depends... when we started to repair the original ship we realized we had to change a lot of its parts. So we replaced virtually most of the old parts of the ship with new ones. But instead of discarding the old parts, the boys thought it would be a nice idea to use all the old parts and create another version of Theseus. So on the left, stands the Theseus repaired and on the right, the Theseus restored from the old parts. "

"So which one is the original Theseus", exclaimed Ray. The guard screamed for his life as he said, "I've told you all that I know! Spare me!!"... Ray was indeed caught in a conundrum. Which ship is the real Theseus? (Source: Leviathon by Thomas Hobbes (1651))

The timing of this paradox fits well with my laptop crisis. As an aside, I replaced the LCD screen with a used one, as this seemed the most efficient, cost-effective fix. Mr. Thinkpad seems well recovered and looks happy. But is he the same Mr. Thinkpad, or is he a different one? Here is the crux of my reasoning - if I anthropomorphized my laptop, then replacing the LCD screen is probably equated to an eye-transplant, or corneal replacement. If a person went through such a surgery (or for that matter even a heart transplant) is he any different from who he was? No.... for his consciousness never ceased to exist and according to me, that is what defines who he truly is. It therefore follows that my laptop is the same one, since I equate it to a human form. But if I didn't equate my laptop so (for it's tricky to define the "consciousness"/identity of my laptop), and viewed it as a combination of physical objects that define it, then replacement of a part of it, breaks down the definition of it's earlier form. Hence my laptop is not entirely the same one. This paradox is along the same lines of the one discussed in the post, "Beam me up". SUMI added a good point about adding dimensions to the person/object in terms of their existence as defined by them, and a third person along the time axis.

So it all boils down to our perceptions and definitions of what constitutes a system or a person, to the point where their uniqueness/identity is not compromised. Aristotle describes a system in terms of four causes - the formal cause, the the material cause, the final cause and the efficeint cause. The formal cause is the formal design of the system (the unique engineering design of the ship, or the laptop), the material cause is the set of all materials/matter that comprise it (the planks, boards, iron, steel, screen, etc), the final cause is the purpose or functionality of the system (to transport people, run software etc), and the efficient cause that signifies who and how the system is made (the workers, the methodology, the tools etc). Now we know for sure that the material cause does change over time, and probably so does the efficient cause. But the formal and final causes remain the same. Does this mean the old ship is the true Theseus? Well, the other ship built out of the old parts does seem to satisfy the formal and the final causes as well....

We don't have precise information as to how much of the ship was replaced and what constitutes as the heart/soul of the ship. Hence being a physical entity, I would define the system as the set of all the material and formal causes. Although the formal cause remains the same, the materials that define the ship's heritage and history are patched in different places. Thus, the real Theseus no longer exists. Both the ships are "new" creations, which hold parts of the material from the original (sort of like children holding some genes from the parent). The guys need to pick the ship that has the most material symbolizing the old ship. And that's tricky too... for I don't know if the mere quantity of materials would matter as much as the weights attached to them.

But if I anthropomorphized the ship, then I can perceive different parts of the ship as metaphors to the human body/brain and claim that the skeleton of the original ship that continued through the time dimension, is the original Theseus (since there was continuity of existence), although the materials/organs it comprises of are different. And that's what we do with cars, laptops and other machines and gadgets around us. But it's an obvious fallacy :). Humans can be associated with an identity due to their conscious state and existence, what sort of identities do physical entities have?


Anonymous said...

now that was difficult..

Both have some parts of the original making both significant but both are not the real ones as they r part old & part new.
How much of the old ship was replaced is unknown if it was 5-10% then the old skeleton still wins. But if it was 50% or more then…!?!
As in your laptop u see it as having a personality. as we call it ‘Manavikaran’ in Hindi. So for u the old one is still ur laptop. But in case of the ship we are not personally attached to it so any of the both could serve the same purpose.
It depends on the person who hired him if he wants the real deck from which the guy dived to end his life of the engine which took him to mid sea..

He should steal both of them. ;-)

SUMI said...

Since in this case it's possible to analyze the problem purely from a pragmatic perspective, the problem becomes slightly easier. If the guy who hired Ray wanted the ship for the sake of its historic value, then he probably needs to steal the one with the old skeleton and new functioning parts. And by historic, I mean just the history of all the people who have come and gone on that ship, the stories that happened on it, like the guy who dived off, and others. I don't mean history in terms of technological history, i.e., for the sake of having parts that were engineered years back, that have come to have a historic value even if they don't function. If the latter is the case, then it should be the other ship he should steal. For now, I assume this is unlikely. So under option 1 , viz "historic value", he should steal the ship with the old skeleton and new parts.

Option 2: The boss wants the ship stolen for a completely different reason, perhaps a material reason.

a. May be he wants to sell the ship to someone else. In this case too, I think he wants the ship with the old skeleton and new parts. If he wants to sell it, a ship with parts that don't function would not sell, as long as we're operating under the material equations.

b. May be there's some cargo in there that he wants to loot. This is harder - if the ship had to be repaired, could they have removed all the goods from it? If the cargo part of the ship is unaffected by the parts that needed servicing, then the goods are probably still in there. So in this case, Ray should ask the guard at gunpoint, about what happened to the cargo and then decide on what to do. If the cargo is in neither ship, then he'll probably return empty handed (Iff he *knows* that his boss was interested only in that). If he is not sure of the goal but knows it's material, I'd say, he should steal the one with the old skeleton and new parts, since there is the possibility of option a.

Under the case that Ray has no clue why the guy wants the ship, I would tend to think he wants the one with the old skeleton and new parts for the above cases. Only under the case that his boss wants the old unfunctioning parts for vintage value (and I am biased here, this may not be the case, but I consider this to have a very small probability) he needs the other ship.

Hmm.... unless, he could sell the parts with a history but that don't function to a museum! This is a hybrid of material and historic (in terms of technology) reasons. In this case he wants the ship with the new skeleton and old parts!

Another point is, what's the extent of malfuncitoning of the old parts? If he can't even get the ship to move, stealing it is ruled out. In this case he can only take the ship that it's possible to steal.

Teh crux is, in order to solve the problem "right" he probably needs to know the goal of his boss. Or as Oorjas suggests, he can play it safe by stealing both the ships (if that's feasible and if the ship with the old parts would move).

In the laptop case, the closest that comes to giving the laptop its identity is perhaps its motherboard. You haven't changed the motherboard, but only one of the peripherals, so I think you have the same laptop! :-)

Perception said...

I am totally confused on this one. I find both ships as real Theseus.But then I think of formal cause (unique engineering design)and final cause (purpose of functionality). I would still consider the older Theseus as the one with unique-original design. Just as a soul for human which is unique and moves from one stucture to another,the material cause and efficient cause both changing.

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Neeraja said...

Oorja - Thanks for the awards! Yeah I guess in this case we all come to the conclusion that there is no longer the original ship, so stealing both or as according to what the boss wants is the best Ray can do.

SUMI - Thanks for patiently working through all of the goal-scenarios! Yeah, it boils down to goals. But it's interesting that we all chose the ship with the old skeleton and new parts as the one with historic significance despite the parts (the boards etc) from where people jumped/danced where no longer part of the ship. Sort of like the passenger seats of the car being replaced... were the seats of significance since thats where people sat, or the car itself? And thanks for making me feel good that my laptop is still the old one! :)

Perception - I think you view the skeleton of the ship as the soul of the ship, but the design could have been literally replicated in the new ship, therefore not making it unique. It boils down to our perception of what defines as the "identity" or "soul" of the ship, and I agree it's hard and confusing. Perhaps physical entities don't have such attributes and we humans try too hard to attach significance to them :)

Anonymous said...

An interesting line of thinking. Identity is a collection of aspects or parameters. These aspects are perceived by a combination of our sense-perception and supported by the ontological framework we ascribe to our world. By the same yardsticks we associate with people, we can ascribe an identity to things. In fact, parodies, personifications, cartoons are all manifestations of utilitarian, material and existential aspects of objects and interactions between objects, whether they are people or inanimate things.

Neeraja said...

Philramble - Thanks for dropping by. Yes, I agree that metaphors, personifications and other forms of creatively relating different aspects of people/things have always been present and is considered part of human creativity and imagination.