The 'Ship of Theseus' Problem [Illustrated]

we would rather be ruined than changed we would rather die in our dread than climb the cross of the moment and let our illusions die the year is 1789 it's november and thomas jefferson after spending four years in paris as the united states minister to france returns at last to the newly formed american republic however upon arriving he notices something very unusual america has changed the people go about their business with a particular idleness and safety and liberty is now taken for granted philadelphia especially is much different where before it was teeming with the chat

of revolution spoken in the language of iconoclasm now the air is one of money tax and governance jefferson felt that in some sense america was a different nation now than it had been when he left it but how could it be different the land was as it had been before the people were for the most part the same and yet for jefferson its identity was unmistakably other we have all undoubtedly had moments in our lives similar to this where we have gone back to familiar places which now feel different or alien to us maybe a

new feature has been erected there maybe it's notably aged maybe it's even been renamed whatever the cause sometimes we just think that the spirit of the thing is not what it was before this makes us ask the question is it really the same place or is it somehow different and from which what kind of factors are important to something's identity as is often the case in philosophy this question harkens back to the ancient greeks more particularly to the greek hero theseus theseus through pioneering the early cinerachismos movement is widely recognized as the founder hero of

athens as well as the venerable slayer of the minotaur despite these heroics however one of the most interesting elements of his story turns out to be something so innocuous as his ship but miles you may ask what could be so important about a ship well as it turns out quite a lot the ship wherein theseus and the youth of athens returned from crete had 30 oars and was preserved by the athenians down even to the time of demetrius valerius for they took away the old planks as they decayed putting in new and stronger timber in

their places documents the greco-roman biographer plutarch this ship became a standing example among the philosophers for the logical question of things that grow one side holding that the ship remained the same and the other contending that it was not the same so over the years the ship's timber are slowly replaced piece by piece until eventually every ore is different and there are no original parts of the ship remaining the question is at what point does the ship lose its identity to help us out will characterize four distinct models of the ship each respective to a

different stage in its repairs ship one will be the original ship returning from crete ship two is the ship after one of its thirty ores has been replaced ship three where half of the oars have been replaced and ship four where every piece of timber is new and no original piece remains thinking of it in such a way will help us better visualize the relevant stages so using the key we've just constructed what are your intuitions does ship two for example still have claimed to be the ship of theseus there's only the difference of one

ore between it and ship one how important is a single ore enough to make it a different ship what about ship three half of the oars are different but half still remain what proportion of original parts does there need to be in order for it to remain the same ship suppose we say 50 for instance by this view ship 2 equals ship 1 because they share at least half of the same ores likewise ship 3 is the same as ship 2 because they share half the same rules and ship 4 is the same as ship

3 for they share half the same rules as each other the replacement tours each ship has at least half the same ores as the previous ship but here's the strange part if we say this then ship 4 has to be the same ship as ship one due to something known as the transitivity of identity this is a property relation within logic but put simply it means if a equals b and b equals c then a has to equal c if you don't want to commit to the chip 4 being the ship of theseus we have

to decide where to draw the line instead by the way if you're finding this conceptually challenging don't worry because that's kind of the point scenarios like the ship of theseus are in a way designed as intuition pumps to borrow daniel dennis description their job is to gauge your intuitions towards the nature of identity and work out what approaches you'll be more inclined towards as a result as for these approaches they're found within the field of myriology the theory of parthood relations broadly speaking there are two main approaches within mereology to the ship of theseus problem

the first is that of myriological essentialism this holds that each part of an object persists by necessity meaning that a thing is the totality of its parts if an object were to lose a part it ceases to be the same object and becomes something else entirely accordingly a myriological essentialist would believe that ship one the original ship is a completely different object from ship two which in turn is different from ship three it's called myriological essentialism because for someone who is convinced by this approach every part of the thing is essential but there is a

slight problem with it in that everything changes over time even if the change is gradual or tiny as the poet offered remarked dripping water hollows out stone not through force but through persistence according to myrological essentialism the stature of liberty of today for instance is a totally different object than the one which existed in 1920. this is due to the small damages it suffered over the years and the gradual chipping away of his copper both both resulting in the loss of infinitesimal parts depending on how atomic the myriological essentialist treats their parts this might count

as a loss of identity but calling them different entities seems quite unintuitive it certainly looks like it's the same object we certainly think of them as the same thing at the very least we can say that we intuit a continuity the myriological essentialist though has an answer to this objection the statues of liberty are different but they bear enough of a resemblance for us to think of them as the same for the sake of convenience likewise ship two for example is similar enough to ship one for us to practically call it the same ship even

though they believe that it's ultimately not if you feel that each part is important and that any changes to the ship alters its identity then you're probably a myriological essentialist the second approach is one of myriological nihilism which can be a bit out there but some find it quite appealing according to the meteorological nihilist composite entities do not exist the world may look like it contains macrophysical objects but the reality is that there are only microphysical ones atoms or myriological symbols accordingly a seat per se doesn't actually exist what exists are the atoms that comprise

it things are divorced from the names remarks the protagonist in nausea they are there grotesque headstrong gigantic and it seems ridiculous to say anything at all about them i am in the midst of things nameless things by this view the whole ship of theseus dilemma is almost a moot point the ship of theseus didn't really exist even at the start it is only the approximate term which we give to the aggregate of a specific set of particles ship one is a different ship from ship two shaw which is a different ship from ship three not

just because the myriological symbols have changed but more importantly because the ships aren't proper objects to begin with as thomas aquinas surmises simple things are neither divided nor divisible composite things do not exist when their parts are divided so existence stands or falls with individuality in line with this if you're very existentialist you're probably going to like this approach and following the myriological nihilist render the whole problem as one of atomism the ship of theseus dilemma though does not stop here no sir it does not for the philosopher thomas hobbs later wondered how it would

change the problem if some man had kept the old planks as they were taken out putting them together afterwards in the same order and had again made a ship of them so hobbes asks what if there was a new ship ship x built from the discarded original pass of ship one well that certainly does complicate things let's look at how it affects myrological essentialism for example more particularly what a myriological essentialist would say at the end of the repair process by this point ship four comprised entirely of new parts would have a ship x as

a counterpart consisting entirely of the original parts assuming that every single shaving of wood from ship 1 is now a part of ship x the myriological essentialist might say that ship x has a reasonable claim to be theseus's ship a far better claim than ship 4 or even ship 2 in fact hops's ship x also complicates things for someone who wants to say that having half the same ores is sufficient ship 3 has 15 of the original ores or 50 of them but its ship x counterpart would have precisely the same amount can we say

in this instance that both have equal claim to be theseus's ship can there be two ships of theseus once these sort of complications show that the dilemma is far from resolved and hopefully excites some thoughts and intuitions on other approaches you could take we see cases like the ship of theseus surprisingly more than we think take shinto shrines like ise jinju in japan they're entirely rebuilt every 20 years owing to the philosophy of impermanence the nike shrine has been rebuilt over 60 times but there is a purported continuity due to the wood all coming from

the same sacred forest a banal and somewhat humorous second example is the sugar babes a band formed in the late 90s which famously underwent such extensive lineup revisions over the years that eventually no original members remained and even in fiction we are regularly exposed to issues of continued identity all of all in asimov's foundation series general smith imposed the man that was used up the tin woodman in frank baum's book the wonderful wizard of oz for instance is the way he is from gradually replacing all his lost limbs with tin in one of the sequels

he even confronts a version of him made from all his discarded flesh parts as to which has better claim to be the true nick chopper sound familiar from this we can see that the ship of theseus is not just a problem in metaphysics but rather a problem for change in continuity in general understanding it is consequently of great importance to appreciating the richness of the issues around us next time you revisit a familiar place perhaps you'll wonder what parts of it have changed and whether enough of it has for it still to be the same

place remember myriological essentialism and nihilism are just two of the many approaches that one can use to help tackle the dilemma there are plenty more in a way though it ultimately comes down to your intuitions take another look at our handy key and really think what do you feel constitutes identity and accordingly which ships do you think are the same and i'm afraid that is the end of the video it was quite heavy philosophical content this time so if you made it to the end well done please reward yourself by liking this video seriously though

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