Is It Still the Same Ship After All Replacements?

  • Thread starter Thread starter maze
  • Start date Start date
Join the discussion
Ask a follow-up here, or get your own question answered by working scientists, mathematicians and engineers — people, not an autocomplete.
Real named experts · corrections over time · the nuance an AI answer skips
Sign up Log in
16 replies · 3K views
maze
Messages
661
Reaction score
4
Over time a sailboat decays and need parts replaced for maintenance. Rusted bolts, damaged parts of the hull, peices of the deck, worn fabric in the sail, and so forth are slowly replaced bit by bit over decades until every single part of the ship has been replaced, and nothing is left from the original.

After all these replacements, is it the same ship as when it was built? How can it be the same ship if nothing from the original remains? Is it a completely different ship? If so, when did it stop being the old ship and start being the new ship?
 
Physics news on Phys.org
This is Theseus' Paradox. What? You think we came in the the last turnip truck?
 
Someone told me it when i was a kid, and I never really figured out a satisfying answer.
 
maze said:
Someone told me it when i was a kid, and I never really figured out a satisfying answer.
Well, there's sure plenty of material about it. Look up Theseus' Paradox or Theseus' Ship.
 
Moridin said:
contingency.
Loquaciousness.

What? Sorry. I thought we were playing random word association.
 
People tend to attach themselves emotionally to inanimate objects. So when the nuts and bolts of the old ship have been replaced, the emotional attachments to previous parts would still exist, hence one might say it's a different ship.
 
what said:
People tend to attach themselves emotionally to inanimate objects. So when the nuts and bolts of the old ship have been replaced, the emotional attachments to previous parts would still exist, hence one might say it's a different ship.
You're suggesting people will attach themselves more strongly to the nuts and bolts than to the concept of the ship itself?

So, if you replace a broken capstan on your sailboat, you tend to think of your sailboat as "Your-Ship-with-some-stranger's-capstan with Your-Capstan-lying-in-a-trash-heap"?
 
what said:
People tend to attach themselves emotionally to inanimate objects. So when the nuts and bolts of the old ship have been replaced, the emotional attachments to previous parts would still exist, hence one might say it's a different ship.
Don't you mean they'd say it is the same ship?

I believe that is the logic the Navy would use for maintaining that the USS Constitution that sailed in Boston harbor in 1997 is the same USS Constitution that first sailed in Boston harbor in 1797.
 
My take is that, once a replacement part is attached to the boat it becomes part of that boat; i.e. the part's ownership is transferred to the boat at that moment. No matter how many parts are replaced, the boat is still the boat.



Of course, that can be carried to another level: what if 9/10ths of the boat is replaced all at once? Does the new 9/10ths get their ownership transferred to the existing 1/10? What if it were 99/100ths?
 
russ_watters said:
Don't you mean they'd say it is the same ship?
Oddly, that does not seem to be what he's saying, since he specifically mentioned attachment to the 1] previous and 2] parts.
 
DaveC426913 said:
You're suggesting people will attach themselves more strongly to the nuts and bolts than to the concept of the ship itself?

The ship itself.

One would have you to inspect the old ship, and possible sail in it in order to define what the "old ship" was to make the comparison. By doing so, and some people are more prone to others, one might develop some sort of emotional attachment.

So, if you replace a broken capstan on your sailboat, you tend to think of your sailboat as "Your-Ship-with-some-stranger's-capstan with Your-Capstan-lying-in-a-trash-heap"?

I suppose if you hung around a rusty capstan long enough to anchor any pleasant experiences on the ship with the device, then yes. A brand new capstan wouldn't bring back old memories that you had, thus even compelling you to say "it's just not the same."

I'm just trying to analyze this psychologically. Of course at an atomic level it will never be the same.
 
what said:
I'm just trying to analyze this psychologically.
Agreed. And psychologically - at least where I come from - people don't attach themselves to nuts and bolts.
 
Or similarly a single flame is constantly replacing the heated smoke particles that it consists of, but we say that the flame is an object that persists through time.
 
maze said:
Over time a sailboat decays and need parts replaced for maintenance. Rusted bolts, damaged parts of the hull, peices of the deck, worn fabric in the sail, and so forth are slowly replaced bit by bit over decades until every single part of the ship has been replaced, and nothing is left from the original.

After all these replacements, is it the same ship as when it was built? How can it be the same ship if nothing from the original remains? Is it a completely different ship? If so, when did it stop being the old ship and start being the new ship?

Reminds me of the axe I have had for over 30yrs, replaced the handle 3 times and head once.
 
Integral said:
Reminds me of the axe I have had for over 30yrs, replaced the handle 3 times and head once.


"My grandfather's axe" is a colloquial expression of unknown origin describing something of which little original remains: "it's had three new heads, and four new handles, but it's still the same old axe."
http://en.wikipedia.org/wiki/Ship_of_Theseus#My_grandfather.27s_axe"
 
Last edited by a moderator: