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created by [deleted] on 28/11/2020 at 05:19 UTC
3 upvotes, 3 top-level comments (showing 3)
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Comment by AutoModerator at 28/11/2020 at 05:19 UTC
1 upvotes, 0 direct replies
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Comment by justanediblefriend at 28/11/2020 at 05:57 UTC*
5 upvotes, 1 direct replies
From something I wrote recently--it's a first draft so try not to assign too much credence to all of it yet:
##Logical possibility vs. broad logical possibility
Let’s start this via ostension, or example. I’m going to list some types of possibility, and give some well-established examples.
###Physical/nomological possibility
**Here are some things which are physically possible.**
* Me running as fast as a cougar.
* Faster-than-light causation.
* Faster-than-light information transmission.
* Repelling an electron with another electron.
* Eating a snack on Neptune.
* Moving a Bishop diagonally to an empty spot on a Chessboard even if there are pieces to capture.
* Moving a pawn diagonally to an empty spot on a Chessboard even if there are pieces to capture.
* Moving a Rook diagonally to an empty spot on a Chessboard even if there are pieces to capture.
* The Sun not having come up today.
* The Sun not coming up tomorrow.
**Here are some things which are physically impossible.**
* Running faster than the speed of light.
* Faster-than-light signal speed.
* Faster-than-light energy transmission.
* Attracting an electron with another electron.^10
* Having a shirt that’s black and white all over.
* The union of two sets with two members having five members—that is, 2+2=5.
* The morning star being somewhere other than where the evening star is.
* The broad logical possibility of the morning star being somewhere other than where the evening star is.
* Having shoes that are completely red and not red.
So, **physical, or nomological, possibility concerns the laws of physics/nature.** As a rough test, you can try to imagine a Universe with our laws of nature with these events, and see if that makes sense. If you can’t think up a sensical Universe with one of the events listed, then the event is actually physically impossible.
When I say “Energy can’t be transmitted faster than light the way information is all the time—that’s incompatible with special relativity!” then I’m saying it’s *physically* impossible for energy to be transmitted faster than light. No matter how things are, so long as the laws of physics are the same, there is no energy anywhere being transmitted faster than light.
###Chess possibility
**Here are some things which are “Chess-ly” possible.** Everything listed related to Chess will be bolded.
* Me running as fast as a cougar.
* Faster-than-light causation.
* Faster-than-light information transmission.
* Repelling an electron with another electron.
* Eating a snack on Neptune.
* Running faster than the speed of light.
* Faster-than-light signal speed.
* Faster-than-light energy transmission.
* Attracting an electron with another electron.
* Having a shirt that’s black and white all over.
* The union of two sets with two members having five members—that is, 2+2=5.
* The morning star being somewhere other than where the evening star is.
* The broad logical possibility of the morning star being somewhere other than where the evening star is.
* Having shoes that are completely red and not red.
* **Moving a Bishop diagonally to an empty spot on a Chessboard even if there are pieces to capture.**
* **Moving a pawn diagonally to an empty spot on a Chessboard even if there are pieces to capture.**
* The Sun not having come up today.
* The Sun not coming up tomorrow.
**Here is a thing which is “Chess-ly” impossible.** Everything listed related to Chess will be bolded.
* **Moving a Rook diagonally to an empty spot on a Chessboard even if there are pieces to capture.**
So, when I say “Here’s what you can do with a pawn” while teaching someone Chess, **I am talking about the rules of Chess.** It’s easy to imagine some way for things to turn out such that the Chess rules aren’t violated, and a Bishop is moved diagonally to an empty spot even as there are pieces to capture. This is fine. But if things turned out in a way where a Rook moved diagonally, then clearly, the rules of Chess would have to be violated. And of course, the stuff unrelated to Chess isn’t restricted. You haven’t broken the rules of Chess if you bring in a pair of shoes which are completely red and not red.
That there is a sense of the word ‘can,’ or a type of possibility, having to do with Chess does not make Chess special in some way. For instance, we can try another type.
###Antichess possibility
**Here are some things which are “Antichess-ly” possible.** Everything listed related to Chess will be bolded.
* Me running as fast as a cougar.
* Faster-than-light causation.
* Faster-than-light information transmission.
* Repelling an electron with another electron.
* Eating a snack on Neptune.
* Running faster than the speed of light.
* Faster-than-light signal speed.
* Faster-than-light energy transmission.
* Attracting an electron with another electron.
* Having a shirt that’s black and white all over.
* The union of two sets with two members having five members—that is, 2+2=5.
* The morning star being somewhere other than where the evening star is.
* The broad logical possibility of the morning star being somewhere other than where the evening star is.
* Having shoes that are completely red and not red.
* **Moving a pawn diagonally to an empty spot on a Chessboard even if there are pieces to capture.**
* The Sun not having come up today.
* The Sun not coming up tomorrow.
**Here are some things which are “Antichess-ly” impossible.** Everything listed related to Chess will be bolded.
* **Moving a Bishop diagonally to an empty spot on a Chessboard even if there are pieces to capture.**
* **Moving a Rook diagonally to an empty spot on a Chessboard even if there are pieces to capture.**
What this shows us is that the word ‘can’ isn’t in some way reserved to talking about very special types of possibility or anything like that. **In different contexts, the word refers to a different set of possibilities, and this set can be fairly ad hoc.** In the case of me saying “You can’t move a Bishop diagonally to an empty spot while there are pieces to capture the way you can with a pawn” while teaching you Antichess, my sentence is synonymous with “In every single possibility where the rules of Antichess aren’t violated, there are no cases of Bishops moving diagonally to an empty spot while there are pieces to capture, but there is at least one case of a pawn moving diagonally while there are pieces to capture.”
The ad hocness of the term ‘can’ and of possibility may seem incredibly obvious—but as I pointed out in the last post in this series, obvious things can be worth saying.
Comment by shyponyguy at 28/11/2020 at 05:49 UTC
4 upvotes, 1 direct replies
Nothing I say here is without controversy, but this is a common way of thinking
"Massive bodies curve space-time" is a nomologically necessary statement, but it is neither metaphysically nor logically necessary.
All the worlds with our laws of nature are ones where massive bodies curve space-time.
It's not metaphysically necessary because the laws could have been different and it is not logically necessary because denying that massive bodies curve space is not a logical contradiction.
"Eminem is Marshall Mathers" is metaphysically necessary, but not logically necessary.
Eminem and Marshall Mather are just two names for a single object. Things are identical to themselves in all possible worlds.
It's not logically necessary because logically the statement is just A=B. So, logically there is no contradiction in denying it. the problem comes from the nature of the object referred to by the statement, not the logic of the statement itself.
"A=A" is logically necessary. Just by its form regardless of its content it will be true and will be true in any possible world.
The Rough Idea:
Nomologically necessary ~ true in all the possible worlds with our physical laws
Metaphysically necessary ~ true in all possible worlds due to the "rules" about how things exist at all in any way with any laws of nature
Logically necessary ~ true in all possible worlds because of the logical rules and the purely logical or formal features of the statement