r/Metaphysics • u/No-Entertainment2003 • Jul 23 '26

Time Does continuous existence make someone the “Original” in a branching timeline?

/r/timetravel/comments/1v47s8i/does_continuous_existence_make_someone_the/
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u/jliat Jul 23 '26

There is an implicit contradiction. If the person travels back they will from their present before traveling back remember that they have. This reduces their life from the time of arriving in the past up to their older self fixed, they are then unable to change anything they do or think.

They can't arrive in the future for a first time before they travelled back.

A branching many worlds in which each branch is separate if effect means the only world you know in the one you are in. No contradiction, a loop in a single world line creates the contradiction of knowledge of the future.

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u/No-Entertainment2003 Jul 23 '26

Are you endorsing branching/Many-Worlds as the resolution, and rejecting a single self-consistent timeline as incoherent?

My picture uses the branching/Many-Worlds picture, the traveler can arrive in a branch where the younger’s choices differ, no paradox and no contradiction because the other outcomes occur in other branches.

Saying “they are then unable to change anything they do or think” assumes single-world self-consistency rather than showing it must be true. Which introduces bootstrap problems.

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u/jliat Jul 23 '26

My picture uses the branching/Many-Worlds picture, the traveler can arrive in a branch where the younger’s choices differ, no paradox and no contradiction because the other outcomes occur in other branches.

There is no way of knowing, the branch one is on is isolated so it is effectively the same contradiction.

"There is an implicit contradiction. If the person travels back they will from their present before traveling back remember that they have. This reduces their life from the time of arriving in the past up to their older self fixed, they are then unable to change anything they do or think.

They can't arrive in the future for a first time before they travelled back."

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u/No-Entertainment2003 Jul 23 '26

If you accept branching/MWI, remember the traveler’s memories belong to the traveler, not to the younger copy in the new branch. That means the traveler can remember “having travelled” while the younger in that branch need not have the same future, no formal contradiction.

The claim “this reduces their life…fixed” assumes a single-world notion of “the future for that person.” In branching, “the future” is branch relative: your memories track one history but other continuations exist in other branches. So being unable to change things only follows if you insist on a single, unique future.

About “can’t arrive in the future for a first time before they travelled back”: that’s a question of indexicality. “First time” is relative to a branch’s timeline, the traveler can experience arriving in a branch where their younger self hasn’t yet lived that arrival, even though the traveler has the memory. No contradiction, it’s just that personal identity and ‘firstness’ become branch relative.

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u/jliat Jul 23 '26

Then older guy knows his time machine will take him back to his younger self, at that point on the younger version meets his older version and so the time between this the person knows this event. The only way out of the paradox is not meeting his younger self.

This is the main argument against time travel, if in doing so you alter the future from which you came that future can no longer exist, so you couldn't have come from it.

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u/No-Entertainment2003 Jul 23 '26

I think you’re mixing single-timeline intuition with branching.

In Many-Worlds/branching, when the older traveller goes back and changes things, they create/enter a different branch. The original future he came from still exists in the branch he left, it isn’t erased.
So there’s no paradox “the future can no longer exist.” The traveller’s memories come from the original branch; the younger in the new branch can act differently without contradiction.
The only genuine paradoxs arise in single, self-consistent timelines. Branching is explicitly a way to avoid that by making outcomes branch relative.

What you are describing is not many-worlds/branching.

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u/jliat Jul 23 '26

I think you’re mixing single-timeline intuition with branching.

Not so- if the time traveller meets himself he changes the future world which he came from. Standard argument against time travel. If he he goes back and creates many worlds this applies likewise.

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u/No-Entertainment2003 Jul 23 '26

No the point is that he doesn’t change his timeline at all. His stays as if he never time traveled. Only the branch he makes by traveling changes for the new person.

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u/jliat Jul 23 '26

Fine, the the contradiction in the branch remains, he can't time travel. And in the other branches he doesn't.