reincarnated wrote:
There is an apple on the left side of my desk. If I pick up the apple and move it to the right side, is the apple which is now on the right side of my desk identical with the one that was previously on the left side?

unenlightened wrote:
If you eat the apple, is what you have eaten, the apple? The apple does not have an identity; it's an apple. It looks like a problem of names to me. When you have eaten it, there is no more apple, but that doesn't mean you have eaten nothing. Is the apple reincarnated each time a molecule of its juices evaporates? Er, not really. It's a bit Zen this question: where is my lap when I stand up? For goodness sake let's be content to be a little vague about these things - we're only talking, and you cannot capture the world in words.

Rilx wrote:
You use ambiguous concept: "identity" may mean a property of uniqueness or a relation of similarity. If A is identical with B, there must exist two distinguishable entities, A and B, both having their own unique identity. Much of your questions are due to this ambiguity.

Rilx wrote:
What's rest, is definitional. What properties and dimensions are counted to identity? If identity of a physical entity (apple) is defined by fixed coordinates in spacetime, well, panta rhei, it has different identity in every moment. If you scratch an apple, it's your definition only whether it's identity changes.

brainpharte wrote:
Great OP, reincarnated.
I think that these questions can help reveal what we put into into and what we presuppose in our conceptions of a unit object.
We differentiate unit objects from one another according to certain properties or predicates that we deem relevant (size, shape, color, weight, composition, location, etc.) Certain predicates or clusters of predicates are at least tacitly considered to be more or less defining attributes of a particular category of object--such as "apple". Beyond the defining predicates we can differentiate the particular object before us from all other objects that qualified in that actegory--we can differentiate our apple from all other apples--by noting "distinguishing features" (predicates that our apple has that the other apples do not.) We can do this by adding precision to the qualifying predicates (the exact color, shape, size weight, texture, surface geometry, ripeness, etc.) and by observing incidental irregularities and changes from its interaction with the world (fingerprints, dust, surface microbes, placement of inspection sticker, etc.)
Our conception of what an object is is a function of the predicates we ascribe to it, which can include its particular location in spacetime. But our conceptions of what an object is do not exhaust the predicates we possibly could ascribe to it. We include or exclude predicates, count them as relevant or irrelevant, according to our purposes. So when some predicate is changed, whether or not this entails that the apple is or is not the "same" apple is entirely a function of what we decide to count as a relevant predicate of the apple in question. If we decide that the exact atomic composition of a given apple is relevant to that apple's identity, then changing that composition is all it takes to differentiate the original from the changed apple, and on that grounds we can construe them as not identical or not the same. But identicalness and sameness are entirely a function of the particular predicates that we decide to be relevant. Thus, whether objects are the same or are different resides in our conceptualizations--in what we count and what we ignore--not in the objects themselves.

Jehu wrote:
According to the ‘principle of the indiscernibility of identicals’, if there is anything at all that may be rightfully predicated of a thing ‘A’ (e.g. its location) that cannot rightfully be predicated of a thing ‘B’, then A and B are two different things. However, although none of the apples you cited in your original post are identical (one and the same apple), neither are they completely different (separate apples), for the they are causally related; the antecedent apple being the ‘constitutive cause’ of the consequent apple. And it is this continuity afforded by a chain of causal relations that leads us to believe that we are dealing with the same thing.

Rilx wrote:
Our time of digital information has brought out a practical problem concerning originals and copies. If we have exact copies of digital documents, we cannot distinguish whether some of them is the original one. Are they all originals or all copies?
I think that concepts "original" and "copy" are no more relevant in this case. There's no physical expression for the original; instead its content - idea - is the "original" and its instances in all forms of expression are "copies".

Tired wrote:
Imagine that any object is in 3d-space and time is continuous. The Since time is continuous, then the apple would be different from where it was before, simply because time has moved forward. Whatever happens in that space in time is irrelevant, because the object is changing with the time anyways. Anything you do to it simply alters the objects form or molecular makeup. It is all relative to time and its position in it.

longfun wrote:
I agree, It all sits in the definitions used by the multiple observers...The "definitions used" biggest common divider can be a little vague for some, but useful for everybody on a certain level, once you go deeper it becomes more and more observer group specific and eventually single observer bound.