Can you jump in the same river twice? Watch

minimarshmallow
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I realise that on the surface, this sounds like a stupid question, but it's another thought experiment from The Pig that Wants to be Eaten (I promise I'm not just going through the book and starting threads - I don't think I even own a copy anymore, may have to see if I can pick one up on Wordery on payday).

Sure, you can jump into "The Nile" twice (I don't recommend this). But what makes that the same river both times, just the name?
Even it's location has changed slightly: in universal terms the earth has spun, carried on orbiting the sun, and the solar system is moving around the galaxy; and in earth terms, there was some erosion of the sides by the water and some depositing of earlier erosions as well.

Then there's the content of the river - the silt, the particles in the water, the wildlife, the fish. They're not the same both times, so can you say it's the same river?

If on another planet, there was a river that exactly matched the composition and then in one given second it occupied exactly the same space that our Nile had occupied and someone jumped into it at exactly that second, had they jumped into The Nile?

Can you jump into the same river twice?
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username1862217
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This reminds me of scenario 3 of the identity problem I posted a while back (that unfortunately got no replies :/). It may be of interest to you OP.
http://www.thestudentroom.co.uk/show...php?p=58240091
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minimarshmallow
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(Original post by Keyhofi)
This reminds me of scenario 3 of the identity problem I posted a while back (that unfortunately got no replies :/). It may be of interest to you OP.
http://www.thestudentroom.co.uk/show...php?p=58240091
Interesting. I hope someone does respond to this. My lunch is almost over or I would.
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leahdw
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What makes 'The Nile' a river? It's probably true that once you have jumped into a river you will (unless you have a lot of luck and you spend your life in the water) never see those precise water molecules again. However the Nile, as a river, is more than just a collection of water molecules at one point in time. Otherwise much of the Mediterranean Sea and the Atlantic Ocean would be the Nile, and I think most people would agree that they aren't.

The definition of 'river' must therefore imply that you can jump in the same river twice, just don't expect that river to be exactly the same as when you jumped in earlier.

To me, it could also be rephrased - can you talk to the same person twice? Or are you the same person you were yesterday? I would say you can, and you are. Yes, the collection of cells may have changed, but you as an entity are still you.
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username1862217
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(Original post by minimarshmallow)
Interesting. I hope someone does respond to this. My lunch is almost over or I would.
Yeah, I think it was a little too long to hold the attention of your average TSR user. But it is certainly a good thing to think about. We call things names, but we have no description for exactly how an identity is defined, and this leads to interesting questions. Much like the one you posted.
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FatherTime
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(Original post by leahdw)
What makes 'The Nile' a river? It's probably true that once you have jumped into a river you will (unless you have a lot of luck and you spend your life in the water) never see those precise water molecules again. However the Nile, as a river, is more than just a collection of water molecules at one point in time. Otherwise much of the Mediterranean Sea and the Atlantic Ocean would be the Nile, and I think most people would agree that they aren't.

The definition of 'river' must therefore imply that you can jump in the same river twice, just don't expect that river to be exactly the same as when you jumped in earlier.

To me, it could also be rephrased - can you talk to the same person twice? Or are you the same person you were yesterday? I would say you can, and you are. Yes, the collection of cells may have changed, but you as an entity are still you.
read my mind
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Arbolus
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(Original post by minimarshmallow)
I realise that on the surface, this sounds like a stupid question, but it's another thought experiment from The Pig that Wants to be Eaten (I promise I'm not just going through the book and starting threads - I don't think I even own a copy anymore, may have to see if I can pick one up on Wordery on payday).

Sure, you can jump into "The Nile" twice (I don't recommend this). But what makes that the same river both times, just the name?
Even it's location has changed slightly: in universal terms the earth has spun, carried on orbiting the sun, and the solar system is moving around the galaxy; and in earth terms, there was some erosion of the sides by the water and some depositing of earlier erosions as well.

Then there's the content of the river - the silt, the particles in the water, the wildlife, the fish. They're not the same both times, so can you say it's the same river?

If on another planet, there was a river that exactly matched the composition and then in one given second it occupied exactly the same space that our Nile had occupied and someone jumped into it at exactly that second, had they jumped into The Nile?

Can you jump into the same river twice?
An entity can be a category of objects which meet certain criteria, rather than a fixed set of objects in its own right. You could consider the the Nile to be "the water molecules A, B, C, D... ", or you consider it to be "the water molecules contained within the depression known as 'the Nile riverbed'".

Taking the former definition requires either that the Nile at each instant is a different entity to all other instants, or it requires that the Nile consists of all the water on the planet. Taking the latter definition, on the other hand, allows for water to enter the Nile and leave it again without changing what the category is. Of course, it then raises the question of how we should define 'the Nile riverbed'...

For myself, I consider that ultimately the only basis for any entity can be the fact that we recognise it as such. Just as most people see no clear distinction between an air mass from the Atlantic and an air mass from the desert, so a species of aquatic insect living in the delta might be too small to see a clear distinction between riverwater and seawater, or between the water and the mud.
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there's too much love
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On the one hand: Nothing is permanent.

On the other: You're making comparisons that are based on different language games. This discussion is therefore void of meaning beyond "things change but retain their name".
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minimarshmallow
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(Original post by there's too much love)
On the one hand: Nothing is permanent.

On the other: You're making comparisons that are based on different language games. This discussion is therefore void of meaning beyond "things change but retain their name".
The name of the river is just an illustration though. The river Nile is just a name for the flowing water in that area. We can call many things by the same name even if they change or are completely different things, is it the same river because it has the same name? I wouldn't say so.
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there's too much love
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(Original post by minimarshmallow)
The name of the river is just an illustration though. The river Nile is just a name for the flowing water in that area. We can call many things by the same name even if they change or are completely different things, is it the same river because it has the same name? I wouldn't say so.

Then you won't accept others saying so because they will be playing a different language game.
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minimarshmallow
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(Original post by there's too much love)
Then you won't accept others saying so because they will be playing a different language game.
Define your position adequately, and debate it with others.
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there's too much love
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(Original post by minimarshmallow)
Define your position adequately, and debate it with others.
Which part is unclear?
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D.G.N.A
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If this is the case, you can't jump at all. It doesn't matter about the river. If you jump into a river, before you even hop back out, you have lost skin cells in the river, maybe a loose hair. And even if you did't, you moved in time and space. Which is a good reason not to fear death - By the time you'll die, you'll (hopefully) be so much older, that it won't matter.


Also, of course you can. A river is defined by: a large natural stream of water flowing in a channel to the sea, a lake, or another such stream. So of course you can: The river is only defined by its place in space, not the water or the time. So yes,of course you can.
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