You may have the same soul - for very approximately defined definitions of soul - but you certainly don't have the same identity.

The idea behind reincarnation seems to be that something persists, and is in some way definitive, but the only available definitions of that something are metaphysical and may not even be comprehensible in human terms.

Many kids appear to show relics of a former identity up to around the age of 4. But even if you assume there are no conventional and mundane explanations for this, there are possible metaphysical explanations that don't require reincarnation.

None of this is very useful scientifically.

All of which is tangential to the original point that we don't really know what identity is. We act as if we do because we have only really have one option - which is that people's personalities tend to be associated with a body we can recognise.

In reality personalities can change drastically because of trauma and illnesses like Alzheimers. So this is just a workable approximation.

In fact we don't even know our own identities. We have a consistent self-symbol but it's not really stable, and elements change dramatically over time. (Example - I like pretty much the same music I did as a teen. I know many people don't, so something that happens to be stable for me isn't stable for countless other people.)

People regularly surprise themselves with unexpected actions. And to a greater or lesser extent everyone has unrealistic beliefs about themselves and others.

So identity usually reduces to a set of observable and consistent behaviours. It should be a set of consistent emotional and mental states. We can't know the latter - not even with test equipment - so we assume the former somehow correlates.

This isn't very useful scientifically either.

>You may have the same soul - for very approximately defined definitions of soul - but you certainly don't have the same identity.

This is a contradiction in terms for me. I have no idea how soul and identity could be different.

We apparently think differently. Changing tastes in music or finding out one's response to a new situation are not inconsistencies or changes to identity, from my perspective.

I don't understand what you mean about "we can't know" emotional and mental states. I can't know your mental state. But it doesn't mean anything to say I can't know my mental state. Who is "I" then? How can there be a mental state of someone who doesn't exist? If a series of 1000 cars was built, what is the paint code for #1001?

I'm doubtful that actions or behaviors can really be inconsistent. I'd prefer to say that when observing someone else, the totality of their actions can be confusing to where I give up trying to model their mental state. But that doesn't mean there isn't one. And sort of, like, the physical world is defined as being consistent, isn't it?

Identity has to be based on physical processes, and therefore I think I'd even say that can't be inconsistent. In principle, there would be a set of numbers that would fully describe a person over time, and it would have to satisfy physical law, and that's inherently consistent.

What can be inconsistent, I think, is explanations for actions and properties of the self. I think it's good to focus on resolving the reasoning and explanations that are used to rationalize everything, but not to confuse it with one's actions and identity.