PHILOSOPHY – Metaphysics: Ship of Theseus [HD]
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PHILOSOPHY – Metaphysics: Ship of Theseus [HD]

December 9, 2019


(intro music) I’m Jennifer Wang. I’m a professor of philosophy
at the University of Georgia. Today, I’m going to talk about
the Ship of Theseus puzzle. This puzzle was recorded by Plutarch, an Ancient Greek historian,
though it’s come up in many different forms over the ages. It goes like this. Theseus was this great
mythical hero of Athens, who sailed off to Crete
and slew the Minotaur, a creature with the head of
a bull and the body of a man. After Theseus came back, his ship was left in the Athenian harbor as a memorial. Over centuries, the
planks of the ship decayed and were gradually replaced. Now, it doesn’t really matter
that the planks decayed, or that the ship still had masts and sails and other ship stuff too. We can simplify the story. Let’s pretend that the Ship of
Theseus is a very simple ship, made of one thousand
planks and nothing more. Let’s also say that the planks
are made of invincible wood, super wood, so that they never decay. In what I’ll call “scenario
one”, the Ship of Theseus has its one thousand
planks replaced very slowly, over the course of one thousand years. That’s one plank a year. So here’s the puzzle. Surely a ship can survive the replacement of one of its planks. In year one, when the
first plank is replaced, it’s still the Ship of Theseus. In year two, when the
second plank is replaced, it’s still the Ship of Theseus, and
so on, through year one thousand. But the ship at year zero,
the original Ship of Theseus, doesn’t share any of the same parts with the ship at year one
thousand, which we can call “A.” So how can A be the real Ship of Theseus? Thomas Hobbes, a seventeenth-
century English philosopher, added a twist to the story. In scenario two, a ship
repairman keeps all of the old planks of the Ship
of Theseus and uses them to build an exact replica of
the original ship, with all of the planks in the same arrangement. So in this scenario, at year one thousand, there are two exactly similar ships: the one whose planks
were gradually replaced, which we called “A” in scenario one, and the one built from the old
planks, which we can call “B.” Now, A has the same claim to
being the real Ship of Theseus as it did in scenario one. But B also has a good claim to being the real Ship of Theseus. After all, it’s made of the
same parts as the original Ship of Theseus, in the same arrangement. But they can’t both be
the Ship of Theseus. Let’s look more carefully at
the underlying assumptions that generate the puzzle. One assumption is that ordinary objects survive gradual change. This is very plausible. You can’t destroy a coat just by removing one of its buttons. Maybe you then ruin the
aesthetic of the coat, but that’s not what’s at issue here. It’s still the same coat. It’s just changed a bit. The principle that ordinary
objects survive gradual change motivates the conclusion that
A is the real Ship of Theseus. Another assumption is that an
object goes where its parts go, so to speak, at least in
cases where the parts are in the same arrangements. Let’s modify our scenario so
that the planks of the ship are gradually removed, but
aren’t replaced with new planks. Again, the old planks are used
to build an exact replica of the ship so that, at the
end of the new scenario, there’s only one ship,
the ship we called “B.” Call this modified scenario
“scenario three.” The principle that an object
goes where its parts go motivates the conclusion that
B is the real Ship of Theseus in scenario three. But it motivates this conclusion in scenario two as well, where
there are two ships at the end. It doesn’t look like
both principles can stay. Which should go? Let’s go through some possible solutions to the puzzle of the Ship of Theseus, some of which involve rejecting
one principle or the other. They all come with disadvantages. Solution one is to deny
the parts principle. This solution involves saying
that in scenario three, the ship at the end is
not the Ship of Theseus, even though it has all the same parts arranged in all the same ways. Solution two involves denying
the change principle: ordinary objects survive some
gradual change but not all. That is, sometime between the year
zero and the year one thousand, removing a plank destroys
the Ship of Theseus. The problem is that this
solution seems arbitrary. Why would removing, say,
plank number 543 destroy the Ship of Theseus, but not number 542? And at that moment, does
the ship being built out of the old planks in scenario two suddenly become the Ship of Theseus? On solution three, the
plank which destroys the Ship of Theseus is not
some middling plank. Rather, as soon as plank number one
is removed, the ship is destroyed. This solution involves denying
the change principle as well, but it offers a stronger
thesis in its place: ordinary objects never survive any change. This view was advocated
by Roderick Chisholm, a twentieth-century American
philosopher, who was inspired by Bishop Joseph Butler,
an eighteenth-century English theologian and philosopher. Butler’s thesis was that
ordinary objects like ships persist only in a loose and popular sense. Whether A or B is regarded
as the Ship of Theseus ends up being something
of a practical matter. According to Butler’s thesis, no
ship really ever survives any change. However, not only
is this view implausible, it implies that there
are one thousand ships where we thought there was only one, as the destruction of
each ship is followed by the creation of a new one. On solution four, neither
the change principle nor the parts principle
needs to be rejected. Rather the solution here is to say that A and B are each the Ship of Theseus. This involves rejecting
the following principle, called the “transitivity of identity”: if X is identical to Y,
and Y is identical to Z, then X is identical to Z. On solution four, A is identical
to the Ship of Theseus, and the Ship of Theseus is identical to B, but A is not identical to B. According to solution five,
the Worm Theory solution, we need to change the way we’re thinking about ordinary objects. Here’s the idea. I introduce scenario two like this: there is a ship at year zero and
two ships at year one thousand, and the challenge is to figure
out which of the two ships at year one thousand is identical
to the ship at year zero. The implicit assumption
that worm theory rejects is that ordinary objects like ships are three dimensional objects,
where the three dimensions are spatial dimensions. According to worm theory,
ordinary objects really have four dimensions: three
spatial and one temporal. So there are no ships wholly present at year zero or at year one thousand. Rather, there is one worm-like
ship which has a part at year zero at one end, and has
A as a part at the other end. And there is another worm-like ship which has a part at year zero at one end, and B as a part at the other. The two worm-like
entities have overlapping parts at year zero. This solution doesn’t require
rejecting transitivity, the parts principle, or
the change principle. After all, it’s no longer
clear what claim we’re making when we assert “A is identical
to the Ship of Theseus” or “the Ship of Theseus
is identical to B.” A and B are not identical
to each other, but nor are either of them identical
to the Ship of Theseus. They both have the object
at year zero as a part. That is all. As you can see, accepting
any of these five solutions comes with disadvantages,
but to resolve the puzzle, it looks like we have to accept
some disadvantage or other. Subtitles by the Amara.org community

100 Comments

  • Reply SpinningFaster February 26, 2016 at 10:13 am

    None of this seems right to me.
    The ship of Theseus is as it is when he docks it. This ship then becomes a memorial.
    The Ship of Theseus is therefore no longer classified as a function, that is to say, this ship is no longer the ship that Theseus uses, or anyone for that matter, it is a representation of something once it is classified as a memorial, or reminder of Theseus's ship. Once the classification changes, the ship moves from function to reminder, therefore all ships over a thousand years or forever never change, as they are only reminders of Theseus's ship. The only true ship of Theseus was when Theseus commanded said functional ship and the ship functioned as his ship. The memorial does not, it stands in depiction of the ideal of the once functional ship.

    Next, I would assert that if Theseus in a 1000 years would come to claim the memorial again and utilize it as his own, then the classification changes when Theseus steps aboard either ship of his choosing, making that ship Theseus's active ship (non-memorial to the event) and the second ship serve the Athenian's memorial.

    So there we have the idea of what is a functional, owned, and utilized ship by Theseus, and what is the memorial of Athens to Theseus by his ship. These things can be one in the same but do not have to be. The function of the forms or classifications are different. Changing the classification changes its function, thus changes the usage of the form, but not the form itself.

    Example: I eat soup from a bowl. When the bowl is empty I place it on my head as a hat. The form never changes, but the function does. The classification of how the bowl is when viewed is solely dependent on the observer.

    And thus so for the Ship of Theseus. Which makes me see that the only real difference here is that one is the Ship of Theseus, a form of memorial status, therefore, as long as it retains that status, is and always will be the Ship of Theseus, no matter what its composition, because of its memorial status agreed on by those that memorialize it, whereas, if Theseus gets in and sails away, that is Theseus's Ship. Continuing, if Theseus boards the ship in a 1000 years and says, "where is my unique area that made me identify this ship as mine?" and those that restored the ship say, "restoration changed the area" then the ship is still stands in memorial, but, if Theseus rejects the ship as his possession, it is not Theseus's Ship. Therefore, The Ship of Theseus is not dependent on the possession of Theseus.

    Memorials serve to remind, therefore, all the Ship of Theseus needs to do to be "The Ship of Theseus" is to remind us. The components are inconsequential.

    I understand that this seems obvious, am I missing something?

  • Reply MalcolmCooks March 14, 2016 at 5:13 am

    The paradox arises because humans define objects. The "ship of theseus" doesn't exist as anything beyond a label we apply to a collection of wood.

  • Reply Albert Kalai March 20, 2016 at 4:54 pm

    WHY NOT GO DEEP DOWN ? – you see a hydrogen atom have one proton, if i add another proton to it , the hydrogen atom no longer remain hydrogen atom it becomes a helium atom , but if i remove one proton from the helium atom, it again becomes a hydrogen atom. Hydrogen and helium atoms are 2 different things, with different properties.And ship of theseus is made up of trillions of atoms.The ship is an inanimate object its a simple problem, but lets take some other complex systems like a complete living cell, or more complex whole living thing.There is another puzzle a virus shows living characteristics only when it is in the host cell or body, or else virus remain as inanimate object , just like a dead body.And last, even an atom have more smaller parts. The place we live in is so crazy, love to study it.

  • Reply tony smith April 4, 2016 at 6:26 pm

    But…..basically after the first plank is replaced, it's 'The Ship of Theseus' with an unspoken caveat.
    When the dude rebuilds it a thousand years later, he can just explain to everyone that has forgotten the history of the ship, that 'technically' it is a replica, whilst he has rebuilt the original.
    Doesn't seem that hard to me.

  • Reply The Pond April 4, 2016 at 7:49 pm

    I think it depends on how you use the name. None of the ships are truly the ship of Theseus, only in the instance it was named.

    Could be cool to apply this problem to people, doesn't the body completely replace all its parts every 7 years? are we still the same person?? id like to think yes, but the way in which you define what something is the question.

  • Reply Peter Struck April 17, 2016 at 6:38 pm

    The core problem of this puzzle arises from 1) the assumption that the only way of attributing identity to this ship is binary („It is / It is not the Ship of Theseus."), which implicitly means that identity cannot be subdivided to basic components, and 2) at the same time the identity is subdivided to 1000 basic components (planks). This contradiction creates a pseudo problem, which can't be solved by usage of the given binary instrument.

    It has to be recognized that in this puzzle you can reduce the identity to a detailed list: The identity called "Ship of Theseus" (SoT) consists of 1000 planks, and nothing more. Therefore each of the planks holds a 1/1000 part of the identity of the ship. By this you can move around components (planks) of this identity without problem. For example in year 250 Ship A has 750/1000 of SoT (75,0%), while Ship B has 250/1000 (25,0%). Which one is now is SoT, which is not? Or are they both? As soon as you ask those questions, you already lost, because you want adress the state of the ships in regards of SoT (75% / 25%) by using a binary vocabulary in a „Yes" (100%) or „No" (0%) pattern. That cannot work.
    The reason, why this puzzle seems so confusing, is that we are used talking binary about identity. When asked in daily life we subconciously would just bring it up to a round figure, because it is easier to express and easier to understand: So in daily life you would say in year 1 „Ship A is SoT", and everybody would agree, because nobody cares that you rounded up from 999/1000 to 1000/1000. But of course when you keep using this convenient pattern of rounding through the course of the 1000 years at some point it falls apart.
     So if you want to be painfully accurate about adressing the state of the ship, you would have to say something like: „In year 250, Ship A has 750/1000 of SoT, while Ship B has 250/1000 of SoT." Of course in daily life no one speaks like that, but this is what the puzzle aims for.
    Somewhere in the commentary section the comparison with the identity of humans was brought up, but I think it is another topic. Because there it is much more complicated to say, what stuff is essential for human identity, and what isn't. When the brain of Phineas Gage was pierced with a iron rod, and his charakter changed dramatically, was he still Phineas Gage? For humans there is not a generally accepted formula of basic components which constitute a certain identity. But for the "Ship of Theseus" there is: Put 1000 certain planks together in a special pattern and you have the Ship of Theseus.

  • Reply Bryo Jafa May 6, 2016 at 3:19 am

    The question of How Objects Survive Change is more about the mind than reality. It's about human cognition, and human language. Is an object just the sum of it's parts? Obviously not. There are more aspects to "A Thing" than the physical parts. There is function, purpose, and real life social context ( how do real people perceive and talk about this object?) – all aspects of the mind. Change is not just physical change but how cognition of a an object changes over time.

    This video presents another aspect to the Whole/Parts question: this is not only a ship, but "Theseus's Ship", i.e. it has meaning based on it's past – – this object has a known history. The questions of how we attach meaning to an object and how meaning persists over time and over the deterioration of an object (and repair) is definitely not a logical problem as this video implies – or at least we do not get much insight from logical analysis – – it's about meaning, which is about language and social cognition of our world as co-created in our linguistic interaction. Ask the Athenians if they think of that ship in their harbor as "Theseus's Ship" 100 years, 400 years, 800 years hence.

    Why is logical analysis not helpful? Because it's too reductionist. Just because logical abstraction works with quantification, i.e. mathematics (we abstract the concept of 1 unit for each thing, and then apply operations to those units, like addition and multiplication), doesn't mean it works with IDENTITY. The Identity of a Thing over Time is a complex feature of consciousness, memory and language/communication. Identity cannot be abstracted and reduced to operational components: a thing is not just parts. That we have single words for things gives the illusion of singularity, but it's just a feature of language and our linguistic logic.

  • Reply thisnicklldo May 12, 2016 at 11:03 am

    A few points:
    1. I learned this as 'Humes' broom' – he had owned the same broom for many years, changing the head 3 times and the handle twice – etc. This phrase 'Humes' broom' seems to have disappeared now. Not important.
    2. For those who want to dismiss this as simply pointless playing with words, consider the very real vintage car market, where the value of restored cars is definitely dependent on the proportion of the original vehicle that remains. Collectors of such vehicles do not want a car consisting entirely of spares (their motives in this are, of course, part of the puzzle). Ordinary people are having to find practical monetary answers to this puzzle.
    3. I am amazed that these Wireless Philosphy videos are not attempting to introduce Wittgensteinian analysis to such problems; personally I feel this is the most penetrating way to go. In particular, trying to understand how our language leads us into many of these famous philosophical traps is at the heart of the issue. Note that calling them 'traps of language' is not the same as dismissing the puzzles as unimportant, but it's a pointer to the direction that analysis should take.
    4. Indeed, how does an entire series on epsitemology jump from Russell to late 20th century philosophers, missing out Wittgensteing entirely, when he seems to me to have much the most intelligent (though hard to understand) things to say.

  • Reply kai graham May 27, 2016 at 7:55 am

    if you built a ship with a substantial part like the car chassis that can not be replaced or can but it stops to be the same ship and you have to rename it
    would we still have the same dilemma

  • Reply Sam May 29, 2016 at 11:19 am

    Solution 5 was advocated by Derek Parphit in his paper "On Personal Identity". It definitely convinced me. It helps that this solution makes the most sense applied to the quantum mechanical world. How to apply it is too complex for a comment though.

  • Reply Michael Esplin May 31, 2016 at 6:15 am

    When a piece is removed (legally, commercially, physically) from the ship, it no longer is a piece of the ship. The replacement becomes a piece of the ship. B is not the ship of Theseus, else that would make legal chaos.

  • Reply Korona June 7, 2016 at 5:50 pm

    Isn't it like a pair of pretenders to a throne? Both have good claims – it's about whose story you find more compelling. It's not contradictory to say X and Y both have good claims to be the King of England even though there can only be one King.

    Equally both ships have good claim to be THE ship of Theseus but there's a degree of flexibility based on the peculiar nature of the scenario.

  • Reply Grimmysiw June 23, 2016 at 5:53 pm

    Random thoughts I had.

    What if you think of the "Spot" in existence that ship A and B are at is a placeholder.

    Thinking Ship A was always the ship of Theseus, Everything its parts touched made it so. As the years went by the "area" that the ship touched from the water, other parts etc. became part of it.
    In that thought that would give Ship B's "area" that same amount of time to acclimate its own "area" to ALMOST become the ship of Theseus.
    So when all pieces are moved ship be is as much as Theseus's ship as it can be.

    Why almost?

    There are still influences on ship A that hold it as The Ship of Theseus, and always will be.

    (Jar of marbles Theory)

    Jar A is full and Jar B is empty at first. Slowly as in the Theory of The Ship of Theseus (TSOT) parts are replaced and reconstructed.
    As jar B gets more and more marbles Jar A will always have just one more marble added to its jar.
    Outside influences add the marbles to Jar A and there for decides what Jar's marbles are the original.

    So do the outside influences have authority over whomever replaces/moves the marbles?

    (Or me tortise theory.)

    The ship just slooooooooooooooowly moved.

  • Reply Dani Levi June 25, 2016 at 9:01 am

    It all comes down to what you consider to be the identity of the ship. If the identity of the ship is composed of every single part, then if you take the first plank it is not the same ship anymore. Or if what makes the ship special from the rest of the ships is its form, as long as this is preserved it is the same ship. Or if what gives its identity is a logo graved into the ship by the hand of the designer, as long as the original is preserved it is the ship of theseus. You got the ideea. If you don't define what makes the ship special or in other words what its identity is, it all remains subjective and the problem has no solution.

  • Reply yu hong lee June 28, 2016 at 3:49 am

    I personally think it's a mix of solutions as solution 1 because the orginal is the first to exist and the orginal parts are used to recreate the ship B, solution 2/3 because if it gets upgraded/repaired and becomes thesus1.4-but we never really count those steps/replacements- and the end(year1000) an entirely new ship(A) with new planks and new name is formed and can be thought as a copyright.

  • Reply yawn74 July 9, 2016 at 3:42 am

    To me the answer is they both are ship of thesus .
    A is the new ship while b is the old ship
    A has the model structure of thesus
    B has the age and the model structure of thesus
    As such if we are saying year 0 ship of thesus , I can only agree that B is that year 0 ship of thesus
    bec of the age !!!

  • Reply psychosavant July 17, 2016 at 11:36 am

    I've had a solution for a long time that I'm surprised to see is not only absent from this list, but I've never seen mentioned by any philosopher throughout history. I think everyone's has had it wrong. The problem is not mathematical, logical, nor philosophical in nature. Rather it's semantic.

    No object, shape, or color exists as a predefined object or an identity tied to it, but rather is given an identity by observers. This identity is a definition, hence the semantics. A ship is not a ship in and of itself, but simply a large collection of atoms arranged in such a way that we choose to identify, loosely, as a ship. The same is true for anything in the universe. Ships, stars, houses, horses, humans, shapes, and so forth. Choosing to call ship A or B the Ship of Theseus is a question of semantics and is simply to subject to human convention (assuming of course that humans are the only observers we're considering as opposed to some other intellectual entities).

    If you see a collection of stars in the sky arranged a perfect circle, you're not really seeing a circle. The stars simply have locations in space independent of each other, and your perception that there is a circle there does not make them a circle. That's just the semantic description you're applying to it. The same is true for the Ship of Theseus. All things in the universe exist in a given state at any time independent of observers applying an identity to them.

  • Reply Schwarzer Ritter July 23, 2016 at 2:07 pm

    I have Theseus Computer.
    All parts but the case have been replaced by now.

  • Reply Brendon Barratt August 4, 2016 at 5:24 am

    Isn't this only a paradox if you think that our cognitive systems impose abosolute definitions on external objects?  Also I wonder if it is reasonable to attempt to correlate mathematics with how the mind imposes meaning on the world?  I think I have to go with the position that under the constraints of our thinking, there is no concievable answer, it seems a bit to me like the experience when you ask yourself "Why is there anything rather than nothing?".  While the statement "Which is the ship of Theseus?" posesses the structure of a question, perhaps it simply isn't a valid question to ask and we just have to live with it.

  • Reply Nicholas Kohles August 16, 2016 at 4:32 am

    While I'm tempted to use the 'it's only the Ship of Theseus because I say it is' argument, I think the Worm solution is missing a tiny piece to win with: Ships A and B both exist (as mental objects, at least) at Year 0. However, at Year 1000, the two ships have separated, with Ship A being the mentally identified 'Ship of Theseus' and Ship B being the physical 'Ship of Theseus.'

  • Reply D4ndelo August 19, 2016 at 2:24 pm

    There is no ship!

  • Reply Pritpal Singh September 1, 2016 at 12:40 am

    as per my perspective if ship is three dimensional X,Y,Z and T ( temporal ) or I call it Time A never equals B but transient as A1…..A2,A3 weather plank changed or not. but yes with replacements A can live infinite to 543 or xxx. at material or non material TIME changes everything Thesus Ship on sea and on shore is new everyday

  • Reply John199312 September 18, 2016 at 6:28 pm

    The Ship of Theseus was The Ship of Theseus.

    Ship A at y=1000 is a refurbished Ship of Theseus that shares none of its parts with the original Ship of Theseus. Ship B at y=1000 is a recreation of the Ship of Theseus from its original parts. At least, if The Ship of Theseus is Ship at y=0.

    It's tautological, because the words assigned to it as a name are just as arbitrary as saying that it is or isn't the same ship at y=543.

  • Reply nimim. Marko Mikkilä October 6, 2016 at 3:20 pm

    I don´t believe there ever was a ship of Theseus:)

  • Reply Khrene Cleaver October 31, 2016 at 8:17 am

    Worm theory is just like twins!

  • Reply dolofonos November 17, 2016 at 11:48 am

    Aristotele's solution is more eloquent, useful, and can be comprehended within 60 seconds of reading.

  • Reply Exhausted NHS Worker January 24, 2017 at 9:12 pm

    professor jennifer wang, I love you!

  • Reply Emre Yıldız January 29, 2017 at 6:36 pm

    Turkish caption please.

  • Reply Josh Walker February 13, 2017 at 9:58 am

    It's solution 4. A square can be many sizes and not be identical, but still a square. The "ship of Theseus" is just another classification.

  • Reply kobisjeruk March 16, 2017 at 6:45 pm

    I just watched 'John Dies At The End' the other day but that wasn't how I came to be here. Never heard about Ship of Theseus before but I had thought about the theory.

  • Reply davit nazarashvili March 23, 2017 at 6:42 pm

    i like worn theory

  • Reply Prech Biscuit April 4, 2017 at 8:57 am

    사람으로 치면, 태어날때 가진 세포 그대로 계속 가지고 있나? 낡은 세포는 죽고 새로운 세포가 생겨나는데, 몇년마다 모든 세포가 다 새로운 세포로 교체된다고 해서 그게 자기 자신이 아니게되나? 세포분열은 자기 몸에서 복제된거라 다르다고? 외부의 음식물을 섭취해서 그 분자로 이루어지는건데 뭐가 달라? 세포분열로 세포가 복제 되어도 자기 자신이라면 배가 완벽하게 복제되었다면 둘다 원본이라 할만하지 않을까?

  • Reply Rui Correia April 4, 2017 at 4:03 pm

    I see it as the original ship (A) that had its planks replaced as being the one and only Ship of Theseus. I ran into this "puzzle" from reading about the inspirations for the Ghost in Shell manga/anime. I sort of see it as the ship having a "soul" of sorts; something you can't touch and doesn't necessarily exist except as an idea. The "soul" of the ship is kept intact while its outer physical shell is replaced even to the point of absolute replacement. So that even if destroyed and not replaced the "idea" or "soul" remains. Don't know if that makes sense.

  • Reply James Coburn April 9, 2017 at 2:45 pm

    Why have I seen no one bring up the idea that the ship of Theseus is just the ship with more than half of the original parts? Only one thing may have over half of the original parts and if no object has over half of the original parts, then it's not a thing anymore (such as "what if 1 board was sent to repair 1000 other ships", the ship of Theseus in this case is gone but the other ships would still be those ships (unless replacing that board made the ship less than half of the original parts, in which case it would be a new ship altogether)) .

    I also like the idea of the current object is the object that currently has the original 'backbone' of the object, be it the keel of a particular ship, the motherboard of a particular computer, or even the brain of a particular human.

  • Reply dantedero April 18, 2017 at 4:00 pm

    How retarded can you be to think that a jacket I bought is the same jacket after I lose a button? It's my jacket with one button less, it's not the same jacket as before, I can't close it completely now. I'll still use the label of "my jacket" because even though it has changed it's the one I have now. I'd use "my jacket" for a different model of jacket too. "Loose and popular" labels, nothing more. With one less plank it's not the same ship Theseus used to sail. It's a memorial that will be maintained but it's not the same ship. Even without replacing planks the ship would still not be the same as Theseus used to travel, Theseus didn't leave a mark on the atoms of the planks assuming they were perfect as the video did. I really don't see the debate.

  • Reply tanmay chaudhari April 28, 2017 at 9:12 pm

    wtf just happened

  • Reply mak13612 May 3, 2017 at 4:25 am

    so, what is the solution????
    Damn!!!

  • Reply Valerio Pons June 2, 2017 at 9:30 pm

    I'd take a real genius to figure how thinking about this problem would be of use to the average person.

  • Reply Hunter Salazar June 19, 2017 at 10:35 am

    I believe it is not about the ship of Theseus but the associations we attach to anything. The ship of Theseus is a conception and our associated thoughts make the replica of the ship more like the actual ship than the aged parts of the first, because it is truer to how it existed when it was Theseus's ship. The original parts being aged means that another dimension (time) has cast them beyond the point of return to their original existence, thus a replica is truer and the aged original is less true.

  • Reply Morgan Fuentes August 3, 2017 at 4:26 am

    Some philosophers think too much that many times they end up overthinking simple stuff.

  • Reply American Movie Podcast August 11, 2017 at 3:38 pm

    This breakdown is really well done. Reminded me of Derek Parfit with the clone of man on mars scenario

  • Reply M F August 15, 2017 at 6:53 pm

    If I have an Oreo, and I eat one of the biscuits then replace it with one biscuit from a different Oreo. Is it still the same Oreo?

  • Reply xxhellspawnedxx September 2, 2017 at 8:25 am

    To me, it seems like one trips himself up by giving a thing an identity, and treating that identity as something objective, rather than as a construct of the mind.

    Whether ship A or ship B has the identity "Ship of Theseus" ends up being subjective, and thereby pointless to discuss. If instead you consider where the planks have been and where they are now, and leave it at that, without assigning some sort of fictitious identity to it, there is no problem, no point of contention. The position in time of an assembly of matter is an objective and immutable fact, after all.

  • Reply soffer September 18, 2017 at 7:48 pm

    Is this not the solution… it is convenient for humans to think of things as static. For example, a rock, or my friend, or my house, or myself. The truth is nothing is actually static. For example we replace every atom in our body every few years. The reality is nothing ever was static in the first place, however for practical day to day purposes it's convenient to think of a rock as not changing. Or a border fence as not changing. There is something that doesn't change. Math is same here as it is in a galaxy a billion light years away. Everything is just energy dancing to one constant beat. That is ultimately what we all are. The underlying laws of nature itself. All the "static" things we think of like the sun, ourselves, is just an illusion.

  • Reply Jack Frost September 23, 2017 at 8:02 am

    In Conscious Universe theory, all objects have a consciousness. This concept is also prevalent in many Eastern traditions. The Ship of Theseus is based on the conscious entity known as the Ship of Theseus. No matter how many parts change, the consciousness remains with the original. Each plank that is lost has it's own consciousness and when the new ship (B) is formed with all the old planks, it is a new consciousness that is composed of the parts of the old ship. Identity relates to consciousness both for what we perceive as living and non-living creatures.

  • Reply Heley September 26, 2017 at 5:25 pm

    But why the question of originality of ship of theseus arised in first place? I mean, physically and philosophically 'change is the only constant thing' is well accepted then what purpose this question might be serving? The name identifies the object but, in reality (again both ways physics and philosphy) at any given point everything is dynamic. Sure it is holding the structure but micro changes are always, at any given point of time going on. So, technically, there never 'the original' ship of theseus existed, as it was ever changing. And if we want to overlook the whole micro changes (in other words visible changes) the ship in every state, well both the ships- the one being stripped to its skeleton and the one being made from the previous one, are ship of thesues, at every single step. Coz both of them have some of the part of other.. provided the remaining parts are not supported with other parts from other ships or other materials. Meaning it is more of a transition. And if we are talking about 1 plank a year for 1000 years, it supports micro changes theory. But question remains the same, why the question of originality in first place?

  • Reply 10,000 subs no videos challenge October 3, 2017 at 5:52 pm

    This isn't a paradox, just a flaw in how we label objects and a question of the exact definition of "Ship of Theseus". Philosophy is retarded.

  • Reply Jason Murphy November 9, 2017 at 1:35 am

    Reading these comments makes one thing clear. A lot of people are missing a good presentation in order to look smart by being dismissive.

    You are fooling no one.

  • Reply Keino Cowan November 24, 2017 at 5:55 am

    So caitlyn Jenner is still technically bruce?….thanks a whole lot!!

  • Reply Dark Sapphire November 25, 2017 at 5:51 am

    The easiest answer is that "was it used by theseus?". Therefore it is the ship of theseus

  • Reply Gordon O'Gairbhith December 7, 2017 at 7:55 am

    There is no such thing as the ship of theseus and never was. We just pretend things have an ''essence'' to simplify our lives. It doesn't have essence from it's physical parts, it just get's it because we think it does. The boat, house, chair or table is just an idea. Nothing more, it just doesn't exist.

  • Reply Gigatony March 3, 2018 at 1:00 am

    Can i use this in court ?
    "Sorry lad. Every cells of my being have been replaced.
    I'm not the same guy that committed murders few years ago"

  • Reply Nicholas Tosoni May 3, 2018 at 10:48 pm

    I always liked it as: "Theseus Jones is the captain of a brand-new Carnival cruise liner. On its test voyage, as soon as it leaves dock, things start going wrong. Fortunately, the company has seen fit to provide him with a barge containing parts and tools for every possible thing that could go wrong. It's simply a matter of taking out the bad part, chucking that into the barge, and replacing it. This goes on until the ship returns to its home, at which point the engineering staff takes an inventory and finds out that a near-exact replica of the ship can be built from the defective parts.

    Let us assume that Theseus himself never actually had to leave the ship when he had to do all the maintenance. Can it therefore be said to be the exact same ship which left?"

  • Reply Nemo May 6, 2018 at 5:23 am

    given as the only thing defining the ship as being unique is it's ownership by theseus, wouldn't, therefore, any ship made of any parts be the ship of theseus as it is owned by theseus?

  • Reply Kuumba DMG May 7, 2018 at 12:13 am

    this is ridiculous the ship remains the same ship until any part of it is replaced, at which point its no longer that ship. it can be a ship or a version of that ship (ship of theasus 1 – 2000) but its no longer that ship just like if you by a jacket from the store and loose 1 button and replace it, it is no longer the same jacket you bought! its still a jacket but not the same jacket maybe a version of the original but if you change something its not the same as it was , or else there is no change! duhhh!! this whole theory is just another example of how easily white folks complicate things. nothing philosophical about it

  • Reply H Baz May 7, 2018 at 3:42 am

    Koja glupost!

  • Reply nunya bisnass May 8, 2018 at 5:36 pm

    I think the three scenarios are obfuscating what THAT ship is. The ship of Theseus has an identity of belonging to Theseus, and the experience of ferrying him on his journeys. If the ship had been replaced piece by piece, it would be the ship of Theseus -x, until x is equal to the whole ship, or its identity being some hybrid variant. A replica can inhabit within an idea, but if it had not the experience of both ownership of and travel with Theseus, its just a replica.

    However if each piece had been salvaged and reassembled in its original entirety, then that salvage also retains the identity with its original experience.

  • Reply Revonawd May 26, 2018 at 4:28 pm

    I've read a lot of the comments here and I don't think many of you actually understand the nature of the problem. When faced with the question "How to define the Ship of Theseus?" most of you seem to answer "carefully". As a joke, it's funny. As a serious answer, it's inadequate, because it's not addressing the real problem here. The author of the video has already given a definition for the ship: a collection of 1000 planks of "superwood" that never decays. What we are talking about here is the justification of referring to either A or B as the real Ship of Theseus when it undergoes change. When you say "it's a matter of definition" or "if we just defined it as exactly as possible, there would be no ambiguity" you are missing the point. ANY definition would have to answer the questions presented in the video: does the Ship of Theseus survive gradual change? If taken apart, would it go where its parts go? Does it only have three spatial dimensions or does it also have a temporal one? You can't avoid having to answer these questions even if the definition was purely a semantic issue, and whichever of the presented answers you chose, you would have to give justifications for it. Most of you are actually just choosing Solution 1 and denying the principle that objects go where their parts go without realizing or justifying it in any way.

    Someone in the comments also said: "All things in the universe exist in a given state at any time independent of observers giving an identity to them." Does that include the identity you, as an observer, give to yourself? Those of you who claim "there is no real Ship of Theseus" or "it's just a matter of point of view" should think of yourselves as the Ship of Theseus. Imagine you, a conscious being, were somehow dismantled into atoms by some teleportation device and then reassembled somewhere else. How can we know you're still the same person who disappeared at the other end? Would you need to consist of the same atoms and have all the same memories for it to be you? What if some were replaced or lost along the way? We can take this even further: what if the machine malfunctions and creates an identical copy of you on one end while you were still on the other? Or if parts of you were taken away and replaced with new ones so you ended up with a new body (like in the video) but somehow your old body was reassembled and brought to life and it retained all your memories? Who would you be then? Maybe "you" would be where your consciousness is, but the other version of you would also have consciousness and from their point of view they simply moved from one place to another. How would you go about convincing your special other that (s)he should be with this particular version of you and not the other?

    The problem here is that even if it was a matter of point of view and identities weren't "real" or "part of the physical reality" they are still part of our social reality. Social realities are in no way less "real" than physical ones – they very much exist and influence our lives and surroundings. Problems like the Ship of Theseus and their solutions have real implications for things like legislation, relationships and politics, so they're not just "moot semantics".

  • Reply Mirokuofnite May 27, 2018 at 9:14 am

    Always came across as a overthinking. Simple example:

    I have a ax.
    This ax is George Washington's ax.
    The handle has been replaced twice and the head three times.
    Is it Washington's ax?
    No.
    At one point it was complete. Then just Washington's ax head or handle. Now neither.

    Another way of looking at it.
    I have Washington's ax in a display case.
    A thief takes the head and replaces it with a look alike.
    Then years later takes the handle and replaces it with a look alike.
    Is it Washington's ax?
    No in the literal sense.
    If I still believe it to be then it is to me
    Until I accept the truth that what was once whole is now not.

  • Reply Madara Uchiwa May 31, 2018 at 12:45 am

    Why the naruto coat though?

  • Reply Charle's Law June 5, 2018 at 6:03 am

    The transitivity of identity is also a form of syllogism correct?

  • Reply IXK01 santiago sinapsis June 16, 2018 at 9:40 pm

    The ship doesnt exists, it is just an ilusion that relays on the definitition you give to the ship

  • Reply Gofuc Yourself July 4, 2018 at 11:37 pm

    After 51% of the ship has been replaced its a different ship.
    And for the second ship it is a replica of the original.
    But none are the original ship.

  • Reply Plugaru C. Sebastian July 11, 2018 at 10:45 pm

    so philosophy is contradicting yourself and ignore that with even MORE questions ?? lol ok, how dumb ^^'

  • Reply Awhad al-din Balyani July 25, 2018 at 11:08 pm

    What's an 'object' in the first place? It's merely a mental construct created from sensory data. Ie there is no thing as 'identity' (eg a boat) in the raw world. Hence, any scenario can be true simultaneously since what is and is not the ship depends on the concept of identity for each subject.

  • Reply MrMentholSlim August 3, 2018 at 3:42 am

    i feel like philosophy majors just do way too much acid.

  • Reply gregg carbo August 4, 2018 at 12:58 pm

    The Theseus ship was anchored in the harbor all of a sudden the ship its function and its meaning changed it became a memorial.
    Given the fact that two objects cannot occupy the same space, the XY coordinates of the memorial provides the key to the puzzle

  • Reply xI2ei August 19, 2018 at 5:54 am

    To all the people saying that this problem is only one of semantics and/or has no value or meaning:

    Consider that this question also arises very uncomfortable implications for the nature of human consciousness and the idea of 'self'. If the ship of Theseus is meaningless semantics, then human consciousness is also a meaningless, semantic construct. And while I imagine some people think this problem is entirely semantic nonsense and also believe human consciousness is equally semantic, I would wager not all of them would.

    The Ship of Theseus is just a simplified abstraction, but it can be applied just as well to the human brain.

  • Reply avehcado August 31, 2018 at 12:57 am

    wtf did i just watch

  • Reply Cory Levings August 31, 2018 at 3:32 am

    The Ship of Theseus never stopped be-ing the ship of theseus as one piece was changed out at a time. Ship B only became identical to Theseus when the last piece was added for completion. Although all the original parts of ship T have been removed and built into ship A the ship of theseus was never dismantled enough to not exist as a constructed object. Once one part is removed from ship T it is no longer part of the whole and goes back to being merely an ingredient. However seeing as now ship A is made from recycled ship T parts we could say it is the reincarnation of ship T while the concept of the original ship T was never destroyed and merely had its parts replaced one by one.

  • Reply Alban Angelito September 8, 2018 at 11:11 am

    Philosophers sure had lots of time back then…

  • Reply Worldview Design September 20, 2018 at 3:59 am

    In response to the worm theory, we can set up the puzzle in terms of 4d ships with part replacements across possible worlds. Same problem.

  • Reply Robin Tapley September 24, 2018 at 1:54 am

    Isn't that a picture of Locke?

  • Reply TheFi0r3 October 8, 2018 at 3:00 am

    First. There was the Ship of Theseus. Now there is Ship of Theseus one and Ship of Theseus Two. Soon enough he will have an entire fleet.

  • Reply Kyle November 16, 2018 at 6:03 pm

    I would change the term "space-time worm" to "wave of identity." A wave travels across the ocean, but the individual atoms change as the wave moves. It's the same wave, but with different parts, and it can split in half. You also don't have to change your way if thinking. You see the wave move, but you don't say the wave is a 4th dimensional object and you only see one part. The wave just moves in space, similar to how the ship moves through time.

  • Reply Green Green December 11, 2018 at 10:45 am

    Chisholm pointed out that we have to differentiate between strict and loose definition of identity. People have the strict definition of identity, like Leibniz' law (identity of indiscernible), while regular objects must be understood by the loose definition, their identity over time is fiction. The problem with a strict definition is when a person changes over time, yet we still say he/she has the same identity. Why is that? Is it like Hume said our projection on the world, us having an impression of a substance but that in reality is just a succession of episodes? How can we talk about identity at all, then? Surely it must be something more than just our language, because the laws of nature is very much based on something being the same thing through time, or is it not?

  • Reply MUSIC GURU January 21, 2019 at 6:42 pm

    Our each and every molecule changes in 12 years so we should ask are we the same person which was born at our birthday ?

  • Reply Michael Boyle February 7, 2019 at 4:54 pm

    This is simple. Titles are abstract like numbers. If you see this shape 3 then you would say it is the number three. However, if you see it again, 3 you know it didn't move. You also know it didn't duplicate itself. You further know intuitively that neither of them are the number three. They are both symbols that represent the number just like this III. If you weren't looking for the number three you might not recognize it right away.

    So in one sense they all have the potential to be the ship but in reality the ship is the one people give the title to. That can change over time (i.e. year one to year 500), but it doesn't depend on the physical parts. If at the end of the 1000 years, ship A is performing a similar function as it did in year one, then it will most likely hold that title. However, if it burned down and was replaced by ship B it would overnight hold the title even though it was a different ship. Titles are abstract.

  • Reply Marc Padilla February 7, 2019 at 7:29 pm

    Seperating it from apetite.

  • Reply ADE 1960 ehrg March 6, 2019 at 3:45 pm

    Maybe you're over thinking this.

  • Reply Vadzianyk 000 March 24, 2019 at 6:26 pm

    Es ist das gleiche Schiff sondern dasselbe Schiff.

  • Reply Mike Qeetus March 28, 2019 at 11:51 pm

    Planks are not what a ship is. Planks are what a ship needs…jack sparrow

  • Reply Erin April 11, 2019 at 12:19 am

    The ship itself is only considered the 'Ship of Theseus' because the title describes the role it's given. It's the ship that Theseus uses. The concept of the 'Ship of Theseus' is a role the ship fulfils, which means Ship A would be called the Ship of Theseus, assuming both Ship A and B existed.
    However, is Ship A didn't exist, Ship B would likely take on the role of the Ship of Theseus

  • Reply Hades948 May 3, 2019 at 5:56 am

    The Ship of Theseus is wet. If it were made of water, it would still be wet. Therefore, water is wet.

  • Reply l ryu May 9, 2019 at 3:14 am

    yeah, guess what? Another way to say the "ship of Theseus" is Theseus' ship. Which means the ship belongs to Theseus. If the ship belongs to Theseus then so do all of the individual parts. When Theseus acquires more parts, those parts also belong to Theseus. When put into the configuration of a ship, they become part of Theseus's ship. The disposed parts, no longer being a part of Theseus' ship, are Theseus' planks.

  • Reply Mikkachu May 17, 2019 at 12:41 am

    Can you don't

  • Reply bryan lieman May 17, 2019 at 4:03 am

    I think even a little change in something will considered a different thing,so the ship of theseus is a different thing every year

  • Reply 8meterwish May 27, 2019 at 10:32 am

    Starting the problem with invincible planks nullifies the problem.

  • Reply Dragon DrawStudios June 13, 2019 at 6:36 pm

    A object is not the same thing if you replace all of it

    When you start to replace it here’s the ratio

    90% Original boat
    10% New Boat

    50% Original Boat
    50% New Boat

    1% Original Boat
    99% New Bot

    100% New Boat

  • Reply Keeley Annabel June 14, 2019 at 7:12 pm

    So what's the answer I'm no wiser

  • Reply Dario Mirić August 12, 2019 at 3:52 pm

    Paradox arises because ship is a mental construct that doesn't have corresponding reality, it is just mental label we project onto phenomenon. If you see that there is no paradox, it is an illusion ?

  • Reply Anthony Trang August 18, 2019 at 9:43 pm

    I do not study philosophy and this 'solution' may have already been covered, but I just want clear feedback on my so called solution.

    I believe that both of the ships are not the original Ship of Theseus that was sailed to the dock.

    Names or labelling are very loose for the sake of simplicity.
    For example: A new born baby receives the name "John" at birth. We call it John for short. Each and every instance that affects John will make him a different person, in the sense of his identity. John learned how to play the piano at 5. His new label is "John who learned the piano at age 5." However, we refer to him by only John for simplicity.

    For the ships of Theseus (defined loosely) :
    * A is known as "The Ship of Theseus that has gone through a gradual change over time."
    * B is known as "The Ship of Theseus that was built from the old planks of the original Ship of Theseus.*
    NEITHER are the original ship as each ship has a new identity.
    Please comment so I know what to think of it, thank you!

  • Reply Nocebo Affect September 4, 2019 at 9:19 pm

    Anyone here from Powell’s class

  • Reply Matthew Thomas September 5, 2019 at 11:06 am

    This is fake

  • Reply Anonymous September 15, 2019 at 3:11 pm

    The question is, who is buying the planks? or otherwise claiming legal ownership. If Theseus is buying the replacement planks, then of course it's still the ship of Theseus. And the person who kept the old planks, built a replica that is not the ship of Theseus because Theseus willingly gave up those planks and forfeit ownership. I don't see how it's a paradox at all, just a logic problem (a very simple one) and objects don't exist in and of themselves, they require an observer and agreed upon terms of society to decide they are a specific object. This has more to do with law than philosophy I think.

  • Reply Graydiation September 21, 2019 at 8:32 am

    Did YouTube recommend this video to you after entering the search the term, "plagiarism" or "fraud"?

  • Reply Something something username October 6, 2019 at 2:09 pm

    I just realized that one Futurama episode with robot Hermes, was possibly referencing this theory. Hermes kept replacing his body parts with robotic upgrades, and Zoidberg reassembled his disposed human parts.

    After replacing his brain, robot Hermes wasn't Hermes anymore, and the brain was put back into Zoidbergs reassembly of his old body parts, bringing back the original Hermes.

  • Reply Patrick Rice October 16, 2019 at 1:18 am

    Hi, in the video Jennifer Wang said she is a professor at the University of Georgia, while the description quotes Stanford University.

  • Reply Kaiju October 25, 2019 at 1:53 am

    Ship of Theseus is just a name. The boat will change over time but call it what you will. We are no different.

  • Reply R.I.P. died from meme overdose He died as he lived November 2, 2019 at 11:40 pm

    Here’s my question what happens when you add back one plank to the edited ship of Theseus then is it now the original ship or a whole new ship

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