It's obvious that we can all change, but how much change is possible for one person to go through without losing their identity and becoming a totally different person? — Purple Pond

That's really an un-answerable question; it's a variation of the famous 'ship of Theseus' conundrum.

Customarily, Buddhists accept the reality of re-birth, but they don't understand it in terms of a soul who migrates from life to life (as do Hindus.) When asked how to interpret that, Buddhists will often answer with a question: are you the same person you were when you were seven, or a different person? The answer is usually understood as 'both the same, and different'. That is taken as an analogy for the relationship of different incarnations also.

(In Tibet, as is well-known, there is a custom of identifying incarnations of lamas who are said to be able to be voluntarily re-born in order to 'save sentient beings'. But it is said that this identity is more like a 'mind-stream' rather than a soul-entity that migrates from life to life, which is against Buddhist dogma.)

your childhood environment that shapes your identity as a person, — Purple Pond

Individuals seem to be born with talents, dispositions, traits, and attributes which I'm sure can't be explained in terms of environment alone. Otherwise everyone born into the same environment would have the same attributes. Whereas you find children that have particular traits and talents.

Talent, in particular, I find very puzzling. Childhood piano prodigies are a good example. Talent, generally, I find very hard to account for in terms of either environment or genetics.

There is, in any case, a body of evidence concerning children who claimed to have memories of previous lives. This was the subject of a decades-long study by a professor of psychiatry by the name of Ian Stevenson. Typical of these cases:

In Sri Lanka, a toddler one day overheard her mother mentioning the name of an obscure town (“Kataragama”) that the girl had never been to. The girl informed the mother that she drowned there when her “dumb” (mentally challenged) brother pushed her in the river, that she had a bald father named “Herath” who sold flowers in a market near the Buddhist stupa, that she lived in a house that had a glass window in the roof (a skylight), dogs in the backyard that were tied up and fed meat, that the house was next door to a big Hindu temple, outside of which people smashed coconuts on the ground. Stevenson was able to confirm that there was, indeed, a flower vendor in Kataragama who ran a stall near the Buddhist stupa whose two-year-old daughter had drowned in the river while the girl played with her mentally challenged brother. The man lived in a house where the neighbors threw meat to dogs tied up in their backyard, and it was adjacent to the main temple where devotees practiced a religious ritual of smashing coconuts on the ground. The little girl did get a few items wrong, however. For instance, the dead girl’s dad wasn’t bald (but her grandfather and uncle were) and his name wasn’t “Herath”—that was the name, rather, of the dead girl’s cousin. Otherwise, 27 of the 30 idiosyncratic, verifiable statements she made panned out. The two families never met, nor did they have any friends, coworkers, or other acquaintances in common, so if you take it all at face value, the details couldn’t have been acquired in any obvious way.

From here. I have quoted this before on this and other forums, generally speaking most people will reject any suggestion of reincarnation out of hand, as it's a taboo idea in Western culture.

I think it highly depends on the framework you use. As you mentioned in your post the "reincarnation" idea is set in a religious or philosophicaly speeking platonic framework.
In this framework you have Substance/Essence that is the actual identiy and Form/Modus the current form you are in. (Don't hang me up based on the terms.)

The most prominent expression of this idea is the (human) soul. Where a person is defined via his/her soul and not via the external form features like size, haircolour, weight, age ect.
Famously expressed in Abrahmic religions the Substance exists independant of the form and can even exist without a form. This makes it possible for the soul to enter heaven or hell while leaving the form/body behind on earth.

The Platonic idea of Substance is mainly derrived from the "existance" of ideal virtual geometrical shapes that don't have their true manifestation in the physical realm. F.e. a true circle doesn't physically exist.

It now seems to be a personal preference wich framework one chooses to endorse. However I see the the percieved Substances as abstractions of real physical objects taking place in human minds that illegitmatly get projected to have a truely independend existance even withouth the existance of physical minds that calculate them. So I view Substance as practical simplifications to solve a general set of problems and don't subscribe a true independend existance to them. However if one does not specificy them back (negate the abstraction when applying the concepts to real instances) one makes a logical error in my view. A good argument for this is that nowadays the Substance of certain objects f.e. Alphabetical letters or roadsigns are better evaluated by computers then by human beings.

Thats why in my view religions as well as fabels (where the prince gets transformed to a frog and maintains his self) are predicated on providing a "plausible" framwork/story to legitmize this assumption. F.e. being able to transform back under the correct circumstances in to a simular form he was in, in case of the fable of the frogprince.
In Asian religions this f.e. is done by introducing the concept of universal justice(Karma) as necessesity/property of the universe. We also find a linking to justice in abrahamic religions. So it rather seems to me to stem from the desire for justice and not from logical reasoning. This is due to Justices and "Soul" being linked in a circular manner. In order for Justice to exist there needs to be a Soul so justices can still take place even if the Body dies and the Soul needs justice to fullfill the (illegitimate)justice demand directed at the universe. However this should not downplay the evolutionary significance that is achieved by justice to organize groups.

Here's what I think. The whole notion of reincarnation is bogus because it's your childhood environment that shapes your identity as a person, and unless reincarnation can replicate your childhood experiences that shapes your personality as you grow up, the whole idea is hopeless. — Purple Pond

Even the most materialist science allows that there is a genetic component to personality. So nature and nurture at least, and then by hypothesis of reincarnation, a third factor, that one might call 'spirit'.

Such a factor has certain essential properties: non-physicality (it survives physical death); independence from experiential memory (because most people cannot remember previous lives and some people lose their memory while living , but presumably not their spirit).

So we are talking an accumulated habit of response, or perhaps developed abilities of awareness, virtue or vice, and so on. One way of thinking about it is to assume a larger grander spirit self in a 'higher reality', that injects a portion of itself into a living being the way one might immerse oneself in a book or computer game. I don't think there is anything contradictory about such notions, but I don't think there is much evidence for them either. You can take @Wayfarer's evidence seriously, or dismiss it as conjuring and wishful thinking, according to taste.

Personally, I like to immerse myself in the game, and forget about higher reality for the duration.

If you believe in the religion of Materialism, the metaphysical theory/belief of Materialism, then it's simple: For you, reincarnation is ruled out.

I don't believe in a metaphysics.

I no longer speak of reincarnation, because it's a Materialist term. Speaking of "incarnation", taken literally, implies a belief in Materialism.

Michael Ossipoff

13 M
2033 UTC

In my studies of NDEs this subject comes up frequently. People often report that they are aware of living other lives. I do not like the term reincarnation because it carries religious baggage. People also report choosing to come here, i.e., to live a human life. The body seems to be more of a receptacle. Once you leave this life your memories come back, it is similar to waking up after a dream.

Often cited evidence for reincarnation is memory of past lives. Personality isn't used as evidence for reincarnation although I believe that in Tibetan Buddhism an inclination for religion is considered as evidence for reincarnate lamas.

What do you think? Does the idea of personal identity impose any problem on the concept of reincarnation? — Purple Pond

The only thing one has to realize to know that the idea is bogus is that you are identical to your body. Your mentality is identical to your brain functioning in particular ways. Supposing that you can continue somehow past your death is suppose that somehow your brain can keep functioning as it does "apart from your brain."

If the question as to whether or not one's personal identity has changed over time is answered according to experience, then doesn't this demonstrate the philosophical uselessness of the idea of personal identity?

Here's what I think. The whole notion of reincarnation is bogus because it's your childhood environment that shapes your identity as a person, and unless reincarnation can replicate your childhood experiences that shapes your personality as you grow up, the whole idea is hopeless. The personality that derives from the mold of childhood is part of your identity. So a different childhood equals a different personality, which in turn equals a different person. I don't think that reincarnation is impossible, I just think that it is severely limited by personal identity to the point that would make it impractical, even for a god.

What do you think? Does the idea of personal identity impose any problem on the concept of reincarnation? — Purple Pond

I don't believe in reincarnation. But I don't think the idea of personal identity that you've sketched poses any problem for the concept of reincarnation.

Would you say it's essential to the notion of reincarnation, that what's said to survive is "a person"?

Isn't there a traditional distinction between something like "the person" and something like "the soul"? The person dies along with the body; the soul is reincarnated. In being reincarnated, the soul gets a new animal body. If it's lucky, that animal body is a human body that becomes a new person. Rinse and repeat....

It seems to me that's a more faithful representation of traditional conceptions of reincarnation than the claim that "persons" are reincarnated. Each time around, the reincarnated entity gets a new body, a new life, a new personality -- a fresh pass at mortality.