Transplant an organ? Why not an entire body?

I'm not sure whether the changes would really be large enough to classify them as a new person. Hormone replacement therapy seems like a pretty damn large change, but I don't think I've heard of a case where there's truly radical personality changes. The same goes for other gland issues and their treatment. Though this is just guessing of course.

This experience of continuity is built from memory, I think I am the same person I was 2 minutes ago because I can remember what it was like to be that person. If I take a roofie or drink too much or sleep walk, I will feel that the things that I did happened to another person, because I don't remember them at all. Likewise, the experience of continuity is often lost - I generally experience sleep as "falling asleep" -> "waking up", even if an EEG would show that I am not even entirely losing consciousness for this time.

> How is everything different? On the contrary, I'd say that actually most things seem to change only marginally and as time periods approach the infinitesimal, so do the changes. And I don't understand what you mean by clear boundaries. Why would there be any? Isn't lacking clear boundaries what actually makes it continuous.

Yeah, that phrase was really bad, I didn't get my point across at all. What I wanted to say is that in physics you actually look at every moment in time individually, even if functions of time are continuous; and you look at every piece of every object individually - any object can be equivalently represented as multiple objects held together by strings (or springs). There is no need or use for object identity across time.

> Let me ask you, why do you care about your future 'self'? That is, why do you not just maximize _your_ (current) pleasure, rather than caring about the experience of someone that you seem to think isn't actually yourself. At the very least, it seems like from your point of view there is no reason to place more importance on your future self than any other future person.

Because in this view, a single experience is extremely fleeting, far too little to gain any great pleasure. Also, my future "self" is the person I can empathize most with in the world, so I feel it is natural to want to help him. Not to mention, for any desire I have, he is the most likely to actually see it through.

Also, we often sacrifice our happiness for other people, often ones that we have much less reason to empathize with than our future selves. Not to mention, of course I occasionally sacrifice my future self's happiness for my current one - such as eating an extra piece of cake, or drinking another glass. But there has to be some limit, especially when I have such an intimate idea of how much the future person will suffer.

> 'time-stable' identity doesn't mean that it must be forever frozen, but rather that it's continuous in the time dimension and happens slowly enough that the subject can experience this.

Yes, I think we mean the same thing by time-stable. It doesn't have to be frozen, but it must be well defined for more than one moment of time (it's pretty trivial to define an object at time T, even the Atlantic Ocean, but it's much harder to define an object that remains itself over some interval T0-T1).

> You can replace parts of the 'soul material', without identity being lost as long.

This is the part I don't understand. In the materialistic computational theory of the mind, it's pretty clear why the mind doesn't change just because cells die and are replaced, or just because every atom in a body is replaced. But if each atom carries a part of the soul, I really don't understand how this works, or at least what it buys you in terms of identity or mind.

There is no problem, and there is no answer. There is only a complex problem from assuming a falsehood and trying to explain it. — there is nothing arrogant about calling out obvious nonsense.

Along with the rest of the body; and note that we can’t treat autism by altering just the brain or the signals sent between the brain and the gut—we have to resort to introducing changes in the gut. To me it looks like a strong indicator that given current level of progress for medical purposes we ethically cannot assign personality and consciousness to any particular part of the body (including the brain).

> Hardcore embodiment people will tell you that you're literally thinking with your gut.

…and while I don’t quite identify with that position, we can’t deny they may be partially right until we exclude that possibility. We haven’t definitively concluded what consciousness is and where it arises.

Many people gravitate towards visualizing thought and consciousness as happening fully in the brain, but it’s not the only way of visualization—and perhaps neither is it even the most optimal: if gut microbiota affects us so much, doesn’t it make sense to include the gut into the feeling of “mind’s I”? Where then to draw the line?

> I'd say it's essentially what we're doing already. We know e.g. hormone treatment as part of sex reassignment causes changes to the brain and definitely influences personality.

For a while I’ve been thinking about continuity, and how it might be among the key puzzle pieces of consciousness. A sex reassignment brings a somewhat fast but still gradual change, while getting a body replacement may not be very different from a death from insider’s view: you go under anaesthesia; but is there a you that wakes up?

But then I guess should we be concerned with that “insider’s view”? What is that insider and does it even exist? (I know this is getting into the territory of the Star Trek Transporter thought experiment and the like, but that it’s easy to end up there might also hint at an insufficient level of knowledge we have about consciousness.)