You didn't read my answer given previously.

Embodied psychological continuity (Locke, Parfit ...); different discontinuous brains-bodies, different discontinuous continuities (i.e. divergent selves). 'Identical twins' are different persons, no? — 180 Proof

You didn't read my answer given previously. — 180 Proof

What makes identical twins different persons?

You didn't reread my answer given previously.

You didn't reread my answer given previously. — 180 Proof

You mentioned twins and I ran with that. What makes twins different from each other?

Again, you didn't reread my answer given previously.

What makes identical twins different persons? — TheMadFool

1) They have different locations.
2) They change on a molecular level within seconds.
3) Can you imagine having two bodies?

Again, you didn't reread my answer given previously. — 180 Proof

To tell you the truth, or if it's all the same to you, I'm asking you to, well, expand and explain (yourself). If it's too much trouble you can decline my request of course.

1) They have different locations.
2) They change on a molecular level within seconds.
3) Can you imagine having two bodies? — SolarWind

The last question seems to be self-refuting. The "you" refers to mind and not the body. Ergo, it's ok within this framework of identity to have two bodies with the same mind. The question proves the prevailing intuition on the matter that identity is an affair of the mind but we need to clarify what exactly about the mind determines identity. You first.

All that you've asked me has been answered, Fool. Read in context, for the purpose of this discussion topic, my meanings are plain and not cryptic. I see no need ro repeat what I've written or expand on it unless the discussion takes a turn that requires it. If you disagree with my statements, then let's gnaw on some bones of contention till we suck the marrow from things-in-themselves. :yum:

The last question seems to be self-refuting. The "you" refers to mind and not the body. Ergo, it's ok within this framework of identity to have two bodies with the same mind. — TheMadFool

You picked one out of three points and answered it with a counter question. You don't have to answer the counter question to realize that it is nonsense to have two separate bodies. One body is in NY and the other in LA. Can they then communicate telepathically as the same mind?

All that you've asked me has been answered, Fool. Read in context, for the purpose of this discussion topic, my meanings are plain and not cryptic.I see no need ro repeat what I've written or expand on it unless the discussion takes a turn that requires it. If you disagree with my statements, then let's gnaw on some bones of contention till we suck the marrow from things-in-themselves. :yum: — 180 Proof

I agree. I need to keep my end of the bargain which I must admit I haven't. Until later then...as and when we can cross swords again - your longsword vs my kitchen knife :lol:

You picked one out of three points and answered it with a counter question. You don't have to answer the counter question to realize that it is nonsense to have two separate bodies. One body is in NY and the other in LA. Can they then communicate telepathically as the same mind? — SolarWind

First off we need to be clear on what a person is i.e. what makes me me or you you? What defines a person's identity?

For my money both the mind and the body together define a person's identity. In the OP's gedanken experiment, the 3D printer produces a faithful copy of the original i.e. if I print Mr. X, what I'll get is another Mr. X. The two Mr. X's will be identical, mentally and physically. In other words the two are the same person.

If you disagree, you need to be both clear and specific as to why?

Your statement that, "...it's nonsense to have two separate bodies..." doesn't quite pack the punch it's intended to because the identity of person is a mind + body affair and there's no difference in those respects between an original person and the copy of that person.

if I print Mr. X, what I'll get is another Mr. X. The two Mr. X's will be identical, mentally and physically. In other words the two are the same person. — TheMadFool

I disagree.

If you disagree, you need to be both clear and specific as to why? — TheMadFool

Clearly and specifically, the degree to which those bodies are identical is a red herring. Each body has a distinct point of view; one cannot see through the other's eyes and vice versa. Same with internal "senses"... there's no direct line between the two bodies' thoughts (though if we're talking arbitrary technology, there could be; but that tech is not in play... only the brains being identical is). If what one person sees triggers a thought, the only way the other one can know about it is through the typical communication route.

ETA: I've discussed the principles I'm applying here earlier in this thread; I believe they underline the core of personal identity. There are two principles correlating to two distinct processes; the one I'm applying to the bodies applies to the "approximate now"... roughly, the period of time where active perception operates. The second principle connects the identity to and defines "past selves" (aka identity through time); it's similar, but invokes memory-of-points-of-view instead of points of view.

In the OP's gedanken experiment, the 3D printer produces a faithful copy of the original i.e. if I print Mr. X, what I'll get is another Mr. X. The two Mr. X's will be identical, mentally and physically. In other words the two are the same person. — TheMadFool

True, but if and only if Mr X & Mr X are entangled entities ... which classically they definitely cannot be (1); to wit: affecting one does not instantaneously, if at all, affect the other at any distance apart (i.e. Mr X does not scratch his right palm when the other Mr X's right palm itches).

Also, the only (1:1 ratio) "faithful copy" of an original is the original due to (A) quantum uncertainty and (B) intractable computational complexity given any arbitrary time constraint for the 3D scanning –> noise/loss-less transmission –> 3D printing process (i.e. map =|= territory). It is physically impossible – violation of classical locality (Einstein) – for 3D printed "Mr X" to simultaneously be 3D scanned Mr X. (2)

Imagine that 3-D scanning and 3-D printing become so sophisticated that you could step into a machine that scanned the exact position and nature of every particle in your body and then send that information to a printer that could reconstitute a body with the same types of particles in the same positions within the body. Assume that the technology is 100% reliable, but part of the process is the destruction and recycling of the original body. Is there any reason to deny that the person who steps out of the machine at the other end is the person who steps into it. Would it matter if it wasn't the same person as long as they were convinced they were? — Aoife Jones

In practice it would be terribly easy to know which one was you.

You would be the one whose eyes you can't see.
You would be the one who experienced the world from the inside out, not the one you experience from the outside in.
You would be the one you experienced now, not the one you experienced at a slight time delay
You would be the one whose voice was moderated by bones in the skull, not the one whose voice was conditioned only by the column of air in the throat
etc etc
There is an incredibly clear asymmetry which would leave you in absolutely no doubt which one you were. Even if, to a third person, you were qualitatively identical.

Each body has a distinct point of view; one cannot see through the other's eyes and vice versa. — InPitzotl

That's another story. Up to the point when the copy is created, since both mind and body are identical, both the original and the copy are the same. Beyond that, because the expereiences of the original and the copy will differ - the physical environment and mental contents will vary - the two will not be the same person.

What's intriguing to me is that the identity of a person doesn't seem to be defined by attributes inherent to the person but by the relationship with the rest of reality. What I mean is that all people are considered the same/identical until they carve a unique set of experiences, physical and mental, out of reality.

An analogy might help: It's like all of us are, say, identical metal balls. The identity of each metal ball is decided by the unique experience it can have for itself and likewise a person's identity is a function of experiences peculiar to it.
There's no such thing as a person if that person can't describe a set of experiences that only that person has had.

True, but if and only if Mr X & Mr X are entangled entities ... which classically they definitely cannot be; to wit: affecting one does not instantaneously, if at all, affect the other at any distance apart (i.e. Mr X does not scratch his right palm when the other Mr X's right palm itches).

Also, the only (1:1 ratio) "faithful copy" of an original is the original due to (A) quantum uncertainty and (B) intractable computational complexity given any arbitrary time constraint for the 3D scanning –> noise/loss-less transmission –> 3D printing process (i.e. map =|= territory). It is physically impossible – violation of classical locality (Einstein) – for 3D printed "Mr X" to simultaneously be 3D scanned Mr X. — 180 Proof

The practical impossibilities of perfect copying are beside the point. Nevertheless, point made, point noted. Thanks!

Up to the point when the copy is created, since both mind and body are identical, both the original and the copy are the same. — TheMadFool

This statement confuses me. I'm thinking at time T=1, there is A1. Then there's a copying process, and by time T=2, there is A2 and B2. "Up to the point when the copy is created" sounds exclusive, like it's describing T<=1. "The original and the copy" is inclusive, as if it describes T=2. Could you clarify?

Beyond that, because the expereiences of the original and the copy will differ - the physical environment and mental contents will vary - the two will not be the same person. — TheMadFool

This sounds a little clearer... T>=2. But it sounds like you're focused on states. So it goes something like, A2 is in state S2, and B2 is in state S2 as well. Then time passes, and by T=3 A2 evolved to A3 and B2 to B3. At that time, A3 is in state SA3 and B3 is in state SB3. So you're saying that since A2 and B2 are both in S2, then they are the same person; but at T=3, they diverge into SA3 and SB3, at which point they are a different person.

I think this is erroneous. Even if A2 and B2 are in the same state, they are nevertheless two instances of the state. A2 is simply one incarnation of the state S2, B2 is a distinct incarnation of S2. A2 and B2, being causally disconnected in the right way (neurally), are already two individuals; what happens to A2 is distinct from what happens to B2. The causally interconnected workings of a brain is what generates a singular personal identity; and here we have two distinct causal frameworks.

Think of it this way. We put A2 into a closed room, and you can observe A2, and his room. B2 we put into another closed room. Some evil genius guy is doing something with that room, who knows. Possibly, of all of the things this evil genius might do, one of them could very well be to perfectly simulate the room A2 is in, so much so that by T=3, B3's state would be the same as A3's state. That's something this evil genius guy just might do... it's so like him to toy with us like that. But who knows.

So now time plays on to T=3. There you are... you have seen A2 evolve to A3. You saw the room's states evolve. So here's the question... did our evil genius, in fact, perfectly simulate the room? And the obvious answer is, you haven't a clue. And frankly, neither does A3 have a clue. That A3 does not know if B3's in the same state is more significant than whether or not it happened that the evil genius did in fact perfectly simulate the room. This lack of knowledge ipso facto demonstrates that A3 is not the same person as B3; the causal disconnectedness that leads to this utter lack of knowledge is enough grounding to say A3 is a different person. I have the same lack of knowledge of what you are seeing that A3 has of what B3 saw.

An analogy might help: — TheMadFool

It doesn't. Again you're focused on state and not instances. The ball over here is a different ball than the ball over there, even if their molecules were exact translations of each other. If I did something to one ball, and the other ball was in the evil genius's room, I cannot conclude the state of the other ball based on the state of the one. They are distinct lumps of matter.

What is a person? What defines a person? This, I believe, is where we should begin in order to resolve the problem that has you and me in its grips.

The causally interconnected workings of a brain is what generates a singular personal identity; and here we have two distinct causal frameworks. — InPitzotl

You need to flesh that out for me. It's rather vague in its formulation and liable to be misunderstood especially considering the complexity of the matter at hand.

What is a person? What defines a person? This, I believe, is where we should begin in order to resolve the problem that has you and me in its grips. — TheMadFool

Take That!

What is a person? What defines a person? This, I believe, is where we should begin in order to resolve the problem that has you and me in its grips. — TheMadFool

I disagree. John defines water as a substance composed of two parts hydrogen and one part oxygen. Julius defines water as the fundamental element that is cold and wet. John and Julius's definitions are incompatible and wholly different, but they are talking about the same thing. They're talking about that stuff that comes out of your taps... that thing you find in lakes and rivers, that falls from the sky in drops a lot. John and Julius aren't starting with their definitions; they're starting with a reference. The definitions are where they wind up. This case is similar... we aren't starting with definitions, we're starting with a reference.

If we start with definitions, you're likely to say something consistent with state-identity, and I'm likely to say something consistent with instance-identity. Neither is really where we start... the definitions are where we wind up. So if you'd like to start at the beginning, I recommend starting with the reference. You and I agree that you and I are examples of different people. There's a particular fundamental reason why we do... that's what the principles I discussed describe.

You need to flesh that out for me. It's rather vague in its formulation and liable to be misunderstood especially considering the complexity of the matter at hand. — TheMadFool

Well let's look at an anomaly. This is sort of old news, so if you have heard it before pardons, but I'll present it as if you haven't.

Alien Hand Syndrome (AHS) is a common side effect of a corpus callosotomy, a last resort surgery where the corpus callosum (the bundle of nerves connecting your left and right brain hemispheres) is severed. AHS is a condition where some of one's limbs appear to have a "mind of their own". From the wiki article:

For example, one patient was observed putting a cigarette into her mouth with her intact, "controlled" hand (her right, dominant hand), following which her alien, non-dominant, left hand came up to grasp the cigarette, pull the cigarette out of her mouth, and toss it away before it could be lit by the controlled, dominant, right hand. — Alien hand syndrome

...and this can get extreme... here's Ramachandran recounting a case where one hemisphere is a believer and the other an atheist:
https://www.youtube.com/watch?v=PFJPtVRlI64

In comparison to these examples, I am of a singular mind, and you are of a singular mind, and our two minds are distinct in these kinds of ways. You don't experience AHS; your left hand isn't tossing cigarettes that your right hand is about to light, and you generally have singular sets of beliefs. Likewise, there is not a corpus callosum connecting our two brains. But each of us have two brain hemispheres which aren't even close to identical, in each connected with a corpus callosum. In contrast, these "two" subjects (the smoker/non-smoker, the atheist/believer) appear to be of two minds each, and we can blame this on the severing of the corpus callosum, which is a manifest example of a break in the appropriate form of causal interconnectedness. I would describe these subjects as being two persons each; the number of identities in their heads doubled as a result of the corpus callosotomy.

To answer this, ask yourself, if destroying you hurts, would you feel the pain or would your copy?

The impossibility of being 'the same X in two places simultaneously' isn't merely "practical", Fool, but fundamentally physical as I pointed out in reference to 'classical locality' & 'non-entanglement of classical Xs'. You're going to have to defeat Special Relativity and QFT to make your (non-physicalist, or dualist-idealist) case ... good luck with that! :sweat:

I don't get you. To my reckoning, the point of contention between us is the meaning/definition of a person. My definition is the standard one as far as I can tell, having to do with mind and body while yours is rather "unorthodox", revolving around a "...causally interconnected network..." I, for one, don't mind engaging in speculation every once in a while but your take on personhood runs so against the grain that it has the, fortunate or unfortunate, effect of sending us all back to square one, forcing us to start from scratch as it were. I'm reluctant to participate in what seems to be a major reworking of known theories on personhood. You may do so of course and let us know if you chance upon anything worthy of our attention.

Secondly, what exactly do you mean by "reference" as opposed to definition. It's not at clear from your post what and how exactly you mean to use that idea to make a case against the fact that "if physically identical and also mentally identical then the same person". By way of showing how counterintuitive and for that reason probably false your position is imagine the following scenario:

There's a person X and fae's presented before you in all faer splendor. Fae is then taken out of sight and then brought back into your field of vision. How do you know that X is the same person and not someone else? Could you answer that question for me please? I think we might be able to resolve our differences with the answer.

The impossibility of being 'the same X in two places simultaneously' isn't merely "practical", — 180 Proof

It's impossible if by 'same you mean numerically identical but not if what is intended is qualitatively identical.

When it is asked if two physically identical human copies are the same person, I don't think anyone is suggesting that they might be numerically identical.

To my reckoning, the point of contention between us is the meaning/definition of a person. — TheMadFool

Your reckoning is wrong. Our disagreement should be about personal identity, not what the definition of a person is. This is the point of contention:

In the OP's gedanken experiment, the 3D printer produces a faithful copy of the original i.e. if I print Mr. X, what I'll get is another Mr. X. The two Mr. X's will be identical, mentally and physically. In other words the two are the same person. — TheMadFool

Somehow, you're counting two Mr. X's, but you're getting "the same" out of it.

as far as I can tell, having to do with mind and body while yours is rather "unorthodox", revolving around a "...causally interconnected network..." — TheMadFool

You do understand, TheMadFool, that it's patronizing to suggest that I, a native English speaker and an explicit example myself of what a person is, do not understand the meaning of the 531st most popular English word, right? If you disagree that my slicing your head into 50 pieces might make it a bit difficult for you to remember what name your mother gave you, then please make your point. Otherwise, let's drop this gaslighting act.

Secondly, what exactly do you mean by "reference" as opposed to definition. — TheMadFool

Reference is the act of referring. A definition traditionally is a statement that attempts to describe what you mean. A reference by contrast just points to what you mean.

I, for one, don't mind engaging in speculation every once in a while but your take on personhood runs so against the grain that it has the, fortunate or unfortunate, effect of sending us all back to square one, forcing us to start from scratch as it were. — TheMadFool

Square one is perfectly justified: you're counting two Mr. X's then immediately saying there's one of something. Two Mr. X's means there are two bodies; two heads and four feet; to dress them up fancy, I need two top hats, two suits, four socks, and two pairs of shoes (two cummerbunds, two pairs of cufflinks, etc).

But you said (essentially) there's one person. I note that you never actually gave your own definition of the 531st most popular word, but you did loosely say it had to do with bodies and minds. Well there's definitely more than one body here. And you're definitely saying there's just one person. So obviously you're not really serious about that "body" nonsense. So let's throw that away. You think there's one mind. Right?

So you tell me. You already have Mr. X 1 and Mr. X 2, with two distinct bodies, that you're claiming are one person. So apparently body count and mind count can differ, and despite saying the word "body" you really don't care how many there are. So let's talk about "Subject A", the smoker/non-smoker (the corpus callosotomy patient with AHS whose left hand tosses cigarettes her right hand is about to light). That is one body. How many minds do you think is there? And why?

. You're unique in the world, friend ... because ... You're an individual ..

. Individuality means your uniqueness - not compared with anybody else. Your incomparable uniqueness: that is individuality.

. Individuality is beautiful; thats how existence has made you, as an individual.

. Ego is comparison ... Ego is your invention ... But ...

. Existence has not given you any Ego ... It has certainly given you an individuality.