Under physicalism, can my consciousness reappear in a different body?

Question

For the sake of argument, let's assume some form of physicalism is true. If physicalism holds, how fundamental can consciousness be? Would it make sense to talk about individual discretized consciousnesses, localized in space and time, and claim there is one consciousness in body X at time t, another in body Y at time t, and so on? Furthermore, under physicalism, does it make sense to track consciousness over time? For instance, is the consciousness in person X at time t ontologically identical to the consciousness in person X at time t+1? What about at t+1000 (in hours)?

If it is possible under physicalism to say that the same consciousness exists at different spacetime locations under the right physical conditions, would it then be plausible to consider the concept of "reincarnation"? Could we replicate the physical conditions that would allow the same consciousness to exist in a different spacetime location, such as by reconstructing a replica of a deceased person’s body, so that the same consciousness that existed before death reappears in the replica?

Conversely, if physicalism suggests that it doesn’t make sense to track the identity of consciousness over time, wouldn't this imply that "my" consciousness from 1 second ago was destroyed, and "my" current consciousness, aware of my hands and the screen in front of my eyes right now, is a completely new consciousness with no fundamental ontological identity to the consciousness from 1 second ago? In this case, wouldn't it be more ontologically accurate to say that the consciousness aware of "my" body 1 second ago was effectively "another person," just as the consciousness in a replica of my body after I die would also be "another person"?

Answer 1

Such "reincarnation" may theoretically be possible, but it's not too meaningful.

Under reductive materialism (which seems to be the physicalist view most consistent with how we understand the world to work and how we do science), one's consciousness is a collection of memories and emotions and behaviours and whatnot, which reduce to some physical "brain stuff" (neurons, brain chemicals, etc.).

There's no fundamental reason why the brain stuff from you at a particular point in time can't exist in another person at some other point in time. Except for the fact that that exact arrangement of physical matter is probably exceedingly unlikely, especially given that it depends on many other external physical processes - part of your consciousness includes memories of things that happened in your life, of people around you, of where you lived, of the technologies and trends and such of the time, of Earth's place in the universe. All of that would need to line up in the exact same way to end up with the exact same result (if things were deterministic). One might speculate about other ways to end up at the same result, or try to boil this down into a "core" of your consciousness, that may be more likely to reoccur, but that would mostly just be speculation.

In any case, such a "reincarnation" would be a distinct person from the "you" who exists at this point in time. It's more like cloning - if you're cloned, whatever experiences your clone has are independent from your experiences.

And they'd go on living without ever knowing that there was someone in the past with their same consciousness.

Consciousness over time

As for consciousness over time, this reminds me of the ship of Theseus - if you have a ship, and you slowly replace the parts one-by-one, at some point you'd have a ship that has no parts in common with the original ship - is that still the same ship? If no, at what point did it become a different ship? And if yes, and you take the original parts and rebuild the original ship, what does that give you?

In any case, the point here is that consciousness consists of parts that are ever-changing. Colloquially, we can say you're the same "you" throughout your whole life, but we can also say you aren't the same person you were some years ago. But if we're being technical and pedantic, we should recognise that this label of "you" is maybe not as well-defined as we might like to think it is.

Answer 2

Many of your questions are actually not all that strongly tied to physicalism. So it may make sense to dispense with that first:

If physicalism holds, how fundamental can consciousness be?

It can't be. Physicalism states that everything supervenes on the physical world, so it can't be fundamental.

Now the rest of your questions deal with things like object persistence. This is a problem faced by every philosophical group, not just physicalism. It also deals heavily with the gap between empiricism and ontological truths. It also has interesting linguistic aspects:

Would it make sense to talk about individual discrete consciousnesses, localized in space and time, and claim there is one consciousness in body X at time t, another in body Y at time t, and so on?

Nothing would be inconsistent here. Nothing precludes making such a statement unless one already believes in an existing system which states that a consciousness in body X cannot ever be in body Y, for some reason completely separate from the question at hand. Indeed, we do see people who talk this way. There are people who speak of "past lives," so presumably it makes sense to them. The real question is probably what one intends to do with the concept, and whether the argument one makes with this concept is rational or not.

If it is possible under physicalism to say that the same consciousness exists at different spacetime locations under the right physical conditions, would it then be plausible to consider the concept of "reincarnation"?

Sure. We can define "reincarnation" to be this. Just be careful because "reincarnation" is a word that has implications for many individuals who use it, and those implications may or may not match with your definition.

Conversely, if physicalism suggests that it doesn’t make sense to track the identity of consciousness over time, wouldn't this imply that "my" consciousness from 1 second ago was destroyed, and "my" current consciousness, aware of my hands and the screen in front of my eyes right now, is a completely new consciousness with no fundamental ontological identity to the consciousness from 1 second ago?

As for this question, I would recommend the SEP article on Temporal Parts. It covers useful terms like "perdurable" which can be used to make very explicitly clear statements. What you describe is an "endurable" view that views time as a series of independent snapshots with no connections between them. Contrast that with a perdurable view which sees objects that "persist" over time. This distinction is independent of the discussion of physicalism. You can make endurable arguments in physicalism; you can make perdurable arguments in physicalism; you can make endurable arguments in other systems (like dualism); you can make perdruable arguments in other systems (like dualisms).

To close out, I'd like to add two unsolicited pieces which I think may be of use. If I may read between the lines, I get the impression you are not a believer in physicalism. An exercise I have found very useful is to attack one's own beliefs with the same ferocity as we attack a belief that is alien to us. I find it a useful exercise that often provides useful fruit. Often I learn more about my own beliefs by taking a challenge I gave, applying it to myself, and realizing the same troublesome quirk applies to myself as well! I don't know what beliefs you hold, beyond the ones you assert here, but see what happens when you shake them!

The second unsolicited advice is to explore what it means for a body to be "the same." I do get the impression you have an intuitive sense of what that phrase means to you, and what you are seeing clearly doesn't sit well with the arguments for physical ism you are reading. Consider what constraints might be needed to be added (or removed) from the concept of bodies being "the same" to make it more palatable. Our bodies are not isolated. They're part of a greater system. Quite often we find that its hard to separate a body from its environment cleanly. Physicists have the concept of "boundary conditions" which helps somewhat, but with multiple interacting systems, there is often emergent behavior which can drive necessity in ontological models.

Answer 3

In physicalism, consciousness is understood as an emergent phenomenon of the brain's physical processes, rather than an object, but a subjective experience. The question of whether the same consciousness can exist in different times and places hinges on replicating the exact physical conditions that generate identical subjective experiences. If these experiences are indeed the same, it could be considered a form of copy, same but not the same.

Answer 4

What is the difference between the clone and the original? Is there a difference? If by "under physicalism" you mean, "assuming there is no difference whatsoever", it follows, obviously, that your wife is back, and you will be pretty happy about that. Why do you ask "should"? Do you actually care about whether your feeling of happiness would somehow be "justified" or "reasonable" or not? It seems unreasonable to me to care about that, in this scenario.

Ask yourself a similar question about the NSS Enterprise transporter: When it reconstitutes your body, has it reconstitutued you or a different person? How would you (that is, the last version of you, just coming out of the transporter room) or anyone else be able to tell? Ok, now something went wrong, and it also created a double. Can anybody (including any of the pair) tell who "the real" you is? Does it matter? (Well, yeah, it might in a society that admits personal property rights for instance.) (For more, see Derek Parfit's Reasons and Persons.)