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Identity Crisis
when is X not X?

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Identity Crisis

reincarnated
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Posted 10/28/09 - 11:54 PM:	#51
Incision wrote: I'll go against the grain and claim it is. Would you say this is the reasoning here? (1) Apple₁ is on the left side. (2) Apple₂ is not on the left side. (3) If apple₁ is numerically identical to apple₂, then if apple₁ is on the left side, then apple₂ is on the left side (instance of the indiscernibility of identicals). (4) Therefore, apple₁ is not numerically identical to apple₂. It looks to me like this argument is unsound because (1) and (2) aren't both true; they only become true if temporally indexed. (1) and (2) should either be true presently (at the current time), or they should be true timelessly. But they're obviously not presently true, because there's presently no apple on left, so (1) is false if it's meant temporally. In fact, there is no time at which (1) and (2) are temporally true. And they aren't timelessly true, either: the thought experiment is only intuitively plausible if we imagine their truth-values changing over time. What is timelessly true is that (1') Apple₁ is on the left side at t₀. (2') Apple₂ is not on the left side at t₁. (3') If apple₁ is numerically identical to apple₂, then if apple₁ is on the left side t₀, then apple₂ is on the left side at t₀. But with that clarification, the conclusion (4) Therefore, apple₁ is not numerically identical to apple₂. doesn't follow. There's no reason why a single apple can't have both the properties of being on the left side at t₀ and being on the right side at t₁. So I'd say there's a temporal-indexing solution to this type of problem: without it, the premises are false; with it, the form is invalid. Problem is that there is more to it than position of the apple in space. The atoms and molecules which make up the apple are not only in constant motion, they are also changing (in the sense of chemical bonds being broken and formed), so that the microscopic make-up of the apple is changing with time. Even if the apple is not moved from the left side of my desk, one can argue that the apple at time t0 is not numerically identical with the apple at time t1 (because of these changes in microscopic makeup).
crumpled bits of paper, filled with imperfect thoughts... we all talk a different language, talking in defence... and if you don't give up, and don't give in, you may just be ok... (Mike & The Mechanics, "The Living Years")

reincarnated
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Posted 10/29/09 - 12:25 AM:	#52
Jehu wrote: The ‘Law of Identity’ (i.e., the first principle of reason) states: that everything is the same with itself, but different from another. From this comes the ‘Principle of the Indiscernibility of Identicals’ which states: that if there is no discernable difference between the two things, then they are not two different things, but one and the same thing. Conversely, if there is any discernable difference between two things, then the two are different things, and not one and the same thing. As already pointed out, this “first principle of reason” is problematic when applied to physical objects – because to say that “something is the same with itself” is just begging the question. When is something also itself? Is the apple on the left side of my desk the same “itself” as the “itself” of the apple on the right side of my desk? In terms of numerical identity, no it is not. Since the atoms and molecules of which any physical object is made are in constant motion, one can argue that no physical object at time t0 is ever “the same as itself” (numerically identical with itself) at time t1. Jehu wrote: I have no preference for which individual is called Socrates, however if you insist on calling both individuals ‘Socrates’, then I will not know which of the individuals I am to bring to mind when I hear the name. Quoting your own explication above: Jehu wrote: if there is no discernable difference between the two things, then they are not two different things, but one and the same thing It is not that “I insist on calling both Socrates”, it is simply the fact that following your own explication of identity, if the copy Socrates is (epistemically) indistinguishable from the original Socrates (certainly a possible state of affairs in principle) then it follows that we have two Socrates. If however you insist that there is only one Socrates, how do you propose to identify which candidate is the true Socrates? Jehu wrote: As I said before, two individuals cannot have exactly the same essential characteristics, for each would have followed its own unique path of evolution. Please identify and explain the “essential characteristics” (of the two individuals who each call themselves Socrates) that you would propose to use in order to identify which is the true Socrates. One cannot use the "path of evolution" directly to distinguish the two, since one has no direct (epistemic) access to this "path of evolution" - one has access only to information about the present state of each Socrates. Of course one can infer "path of evolution" from present day information, but such inference is far from foolproof (it could be arranged that both candidates presented essentially identical present-day information regarding their supposed paths of evolution, and yet one would still be a copy and one an original). Edited by reincarnated on 10/29/09 - 01:56 AM
crumpled bits of paper, filled with imperfect thoughts... we all talk a different language, talking in defence... and if you don't give up, and don't give in, you may just be ok... (Mike & The Mechanics, "The Living Years")

Incision
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Posted 10/30/09 - 08:27 PM:	#53
reincarnated wrote: Problem is that there is more to it than position of the apple in space. True, however I'd say that we could pull the same temporal-indexing trick on the rest of its features. It's not true that apple₁ is fresh while apple₂ is decayed; rather, the first apple is fresh at t₀ and, later, the other is decayed at t₁. There's no reason, as far as the indiscernibility of identicals is concerned, why the same apple cannot have both properties. In general, for any of the putative cases of an apple₁ being F while apple₂ is ~F, I'd say that what really true is that one apple is F at t₀ and ~F at t₁.

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Posted 10/30/09 - 08:29 PM:	#54
Here's the SEP making the same point in English: Hume argued that identity over time was a fiction we substitute for a collection of related objects. Such views can be seen as based on a misunderstanding of Leibniz's Law: if a thing changes something is true of it at the later time that is not true of it at the earlier, so it is not the same. The answer is that what is true of it at the later time is, say, “being muddy at the later time”, which was always true of it; similarly, what is true of it at the earlier time, suitably expressed, remains true of it.

exel+two
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Posted 11/03/09 - 02:04 PM:	#55
The apple's identity is only your perception of it. I.e. the apple is the same apple as long as you say it is. The apple's identity is an idea, and thus, as long as you hold that idea to be true, it remains true. Thus it is with reality. As long as you are convinced something is real, it is: as long as you think the apple is called apple, it is.

Jean Francoise
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Posted 11/04/09 - 04:42 AM:	#56
You have formulated the problem of identity as an instance of the Sorites paradox. Literature concerning that paradox may answer some of your musings.
Emptiness whispers in riddles.

reincarnated
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Posted 11/04/09 - 06:11 AM:	#57
Incision wrote: Here's the SEP making the same point in English: Hume argued that identity over time was a fiction we substitute for a collection of related objects. Such views can be seen as based on a misunderstanding of Leibniz's Law: if a thing changes something is true of it at the later time that is not true of it at the earlier, so it is not the same. The answer is that what is true of it at the later time is, say, “being muddy at the later time”, which was always true of it; similarly, what is true of it at the earlier time, suitably expressed, remains true of it. Which is clearly begging the question. In the sentence "if a thing changes something is true of it at the later time that is not true of it at the earlier" we implicitly assume that "it" at the later time references the same "it" as at the earlier time - but why? It's like Jehu's Law of Identity - that "something is the same with itself" - which also begs the question. On what basis do we claim that the "it" at the two different times is identical? On what basis do we claim that "itself" at time t0 is identical with "itself" at time t1? Edited by reincarnated on 11/05/09 - 06:16 AM
crumpled bits of paper, filled with imperfect thoughts... we all talk a different language, talking in defence... and if you don't give up, and don't give in, you may just be ok... (Mike & The Mechanics, "The Living Years")

reincarnated
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Posted 11/04/09 - 06:23 AM:	#58
exel+two wrote: The apple's identity is only your perception of it. I.e. the apple is the same apple as long as you say it is. The apple's identity is an idea, and thus, as long as you hold that idea to be true, it remains true. Identity is therefore a subjective concept, not an objective one. I can go along with that. Throws the notion of rigid designators into the trashcan though, doesn't it?
crumpled bits of paper, filled with imperfect thoughts... we all talk a different language, talking in defence... and if you don't give up, and don't give in, you may just be ok... (Mike & The Mechanics, "The Living Years")

Incision
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Posted 11/04/09 - 01:42 PM:	#59
reincarnated wrote: On what basis do we claim that the "it" at the two different times is identical? On what basis do we claim that "itself" at time to is identical with "itself" at time t1? Good question. I don't know on what basis we'd do that (except that it seems like common sense); I'm not claiming to have an answer to all the OP's questions. All my argument shows is that there's no conflict between the identity of indiscernibles and "the same apple that was on the left is now on the right."

reincarnated
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Posted 11/04/09 - 09:14 PM:	#60
Incision wrote: Good question. I don't know on what basis we'd do that (except that it seems like common sense) OK, I can go along with that. Many commmon sense notions seem to work in everyday life, but fall to pieces when examined close up.
crumpled bits of paper, filled with imperfect thoughts... we all talk a different language, talking in defence... and if you don't give up, and don't give in, you may just be ok... (Mike & The Mechanics, "The Living Years")

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