The Reasoning behind The Sundering? (*6.0 Endwalker Spoilers*)

[Rosenstrauch]

There are two issues with this.

First, the Eighth Umbral Calamity timeline still exists, even after G'raha alters it. In that timeline, Azem is still dead and cannot travel back in time to Elpis. You can't solve this problem from another timeline. You've just created a Grandfather paradox. That's why Biggs the Third writes 'We shall remain forever on different pages of history─and different books, besides'. The events of one no longer affect the other.

Yes, it still exists. See: my image, where I account for this.
The WoL being dead is irrelevant. They don't have to travel to the Unsundered Etheirys, because we already did so. See: my image, where I account for this.
The Grandfather Paradox ("If you travel back in time to kill your Grandfather, you will not be born, and thus can't travel back in time to kill your Grandfather") is only relevant in scenarios where traveling back in time negates the possibility of doing so. There are a few solutions to this paradox, such as "you can succeed, but you'll cease to exist", "you can succeed, but your past will cease to exist", "you can succeed, but you'll split the timeline", and "you can never succeed, something will always stop you from doing so". And probably more.

G'raha traveling back in time to undo the Eighth Umbral Calamity ran headfirst into the Grandfather Paradox. The writers' solution to this was the continued existence of the time traveling G'raha Tia, the time traveling Syrcus Tower, and short story "An Unpromised Tomorrow" demonstrating that the future he left continued to exist. All of these combined are the third solution I presented.

The WoL in the Eighth Era timeline (who is dead) not traveling back in time to Elpis is not an example of the Grandfather Paradox, because they're not the one who traveled there in the first place.

Biggs the Third is not an omniscient observer. He has no idea what the timeline actually looks like, and anything he says about it is pure speculation.

The second, what you're proposing hinges on the idea that everything up to Elpis was always destined to happen and nobody had any free will in the matter.

Not quite. From the perspective of an omniscient observer, every action is strictly deterministic. From the perspective of those acting within the timeline, their choices are entirely their own.

Until G'raha makes the decision to go back and change the timeline, the time travel event is not possible.

That a person's future actions aren't possible until past actions have taken place is irrelevant. This holds true even if the future actions take place in the past, and past actions take place in the future.

As a result, there has to be a set of events on Elpis that predate this decision. It can't be a completely closed loop.

This is unfalsifiable. There is no observed set of events that were negated by a time traveler causing a closed loop.

That's also why Venat says that 'a conjunction has begun to form', and not 'this conjunction was always destined to form'.

What she actually says is this: "Or perhaps the erasure of our friends' memories has sown the seeds of a conjunction between us."
The word "perhaps" is important here. As with Biggs the Third, Venat is not an omniscient observer. At the time of our departure from Elpis, she is not aware of whether or not she's within a closed loop. It's only after we meet her post-Aitiascope that she confirms she was—and by that point, the loop is already closed.

[Lyth]

...

Let's say that we live in a universe where free will exists. If that's the case, the entire timeline doesn't exist from start to finish its entirety, because otherwise we're just making decisions on rails. A decision doesn't exist until its made. As such, I should be able to take any subsection of the timeline from the start to a particular timepoint without running into any paradoxes. Let's start with an easy one.

1. Start
2. Elpis

In this subsegment of the timeline, we haven't made any decisions about travelling back in time. Yet events happen on Elpis. This in itself suggests that there was originally some set of events on Elpis that is similar to, but not exactly identical to the original. Let's try a slightly more complex one.

1. Start
2. Elpis
3. Sundering
4. ARR/Heavensward/Stormblood
5. Eighth Umbral Calamity

Let's stop here. Again, this timeline also requires a set of events to happen on Elpis that occur without involving time travel, because Azem is dead. Now let's keep going to the present.

1. Start
2. Elpis
3. Sundering
4. ARR/Heavensward/Stormblood
6. Eighth Umbral Calamity
5. G'raha alters timeline (original events overwritten)
6. Venat tells us about a conjunction between two timelines
7. Time travel to Elpis (original events overwritten)
8. Battle with Meteion

So we have a 'time loop', but it's not a strict circle. We can unroll it out and lay it out flat. We re-write two parts of the timeline, but the parts that we re-write have an original sequence of events that gets replaced by an altered one.

In order for your explanation to work, everything must be pre-ordained from the start. If that's the case, then we don't need to for all sub-timelines to be consistent as well, because the future has always existed the way that it has. G'raha's actions in Shadowbringer are critical. Until the moment that he makes his decision to travel back in time and alter events, the events in Elpis cannot play out the way that they currently have. In order for that flag to be raised even before the event happens, he has to be fated to make that choice. Although it's unclear if events in a separate timeline can re-write your own, and we have nothing except your claims that it works this way and that Biggs III is wrong. Which is fine, I don't mind seeing a bit of headcanon as long as there's some attempt made at internal consistency.

So yes, this is all very relevant. I'm just curious what your starting set of axioms are, because that determines whether the rest of your explanation is internally consistent or not.

And I'll leave you with the last point, which we still couldn't explain before: Why is past Azem seemingly able to predict the future? Again, I think that this isn't the case, and that the original sequence of events has been disrupted.

[EaraGrace]

And I'll leave you with the last point, which we still couldn't explain before: Why is past Azem seemingly able to predict the future? Again, I think that this isn't the case, and that the original sequence of events has been disrupted.

I don’t think we are supposed to be able to answer that, as that’s clearly a question that will be expanded on in the Pandaemonium quest line.

[Rosenstrauch]

Let's say that we live in a universe where free will exists. If that's the case, the entire timeline doesn't exist from start to finish its entirety, because otherwise we're just making decisions on rails.

Well, let me stop you right there. First off, we're not talking about our universe. We're talking about a work of fiction. If you wanted to get strictly literal, the characters in a work of fiction have no free will at all because their choices are determined by the author(s) of such fiction. The only stories where this isn't true would be, off the top of my head, the results of roleplaying between a group of individuals.

Second, far more intelligent and well-read people than either of us have been debating this specific philosophical topic for millennia. I sincerely doubt either of us will have anything new to add to that conversation—Hell, I had to look up terms just to find what those systems of belief even are, because I am not a philosophy major. The worldview that disagrees with the one you're positing here is called compatibilism, by the way.

Thirdly, the impression I'm getting from your post is that the writers must adhere to your personal philosophical worldview, or else the story is written incorrectly. I, meanwhile, am doing my best not to judge the contents of the story by my worldview at all—an arguably self-defeating effort, I'll admit, since the only perspective I have on the story is my own. But that's my preference when it comes to discussing the events of a work of fiction. And the reality of a work of fiction is that each and every time travel rule is up to the author's discretion, not ours. Beyond outright asking them, the only way we have to determine what rules are in play is to observe the story for ourselves.

And that's what I've done. If we ever have an expansion where we fight the Time Devourer within the Tesseract/Darkness Beyond Time, where discarded timelines settle like detritus on the ocean floor, then I'll accept the existence of discarded timelines. Until then, they remain an unfalsifiable possibility, and insisting that they must exist or the story doesn't make sense is just silly.

[Veloran]

Well, let me stop you right there. First off, we're not talking about our universe. We're talking about a work of fiction.

I think that was the royal "we". As in, the "we" of those in-universe. I agree that the notion of predestination undermines many of the themes presented throughout the game, and that setup has about as many issues and implications for the story as we've seen as that of a multiverse/many-worlds interpretation of time.

If we ever have an expansion where we fight the Time Devourer within the Tesseract/Darkness Beyond Time, where discarded timelines settle like detritus on the ocean floor,

Honestly given the sheer abuse of time travel within the narrative that probably should be the next saga.

[Lauront]

I think that was the royal "we". As in, the "we" of those in-universe. I agree that the notion of predestination undermines many of the themes presented throughout the game, and that setup has about as many issues and implications for the story as we've seen as that of a multiverse/many-worlds interpretation of time.

Yep, give it a few expansions and we'll be fighting the Arbiters of Fate or something similar. Maybe they can borrow some ideas from 7R for it.

Determinism itself as an idea is often rooted in the notion that it is impossible based on physical (and any other derived) laws to explain something like free will in humans (or any other living being.) That, along with consciousness, remain as exceedingly thorny philosophical issues because of that constraint. XIV on the other hand has immaterial souls, about which we know very little, beyond that they have an aetheric composition and perhaps some other irreducible aspects, to which dynamis might relate, so it's easier to introduce free will as a concept - on the other hand, it is also that much easier to introduce some thing that rigidly ensures certain outcomes for whatever purpose. But with that all said, if anything our universe is the readier candidate for deterministic explanations than a setting with rather elusive things like souls.

That preordainment from beginning to end is part of what I don't like about some of the theories hinging on the timeline playing out in a specific way irrespective of what actions take place and correcting itself to ensure that outcome is arrived at. We'll see how the writers address this, if they deign to.

[Lyth]

...

No. I'm simply illustrating how your explanation hinges on events (i.e. G'raha's alteration to the timeline, our return to Elpis) as having always been destined to have happened, irrespective of any conscious choices made by the characters. Which is certainly possible, but I wanted to be sure that this was actually the philosophical stance that you were taking. I'm simply observing your starting premises. There's no need to worry about getting pulled into a Wikipedia-sourced internet debate on causality to defend your claims. It is possible to explain the timeline without events being fated to occur, but it requires that Venat gain her knowledge of the future only duriing the events of this expansion i.e. it's not 'all according to plan'.

I think it's worthwhile to attempt to piece together the bits that we have on how spacetime magic works in universe given that it's been used an awful lot in the past two expansions, it has ties to Allag and shard travel, and it at least visually appears to be similar to Azem's own signature magic. I think that there's enough detail from the in-game lore for this to be a hard magic system, and I'd like to know what the rules actually are.

[EaraGrace]

No. I'm simply illustrating how your explanation hinges on events (i.e. G'raha's alteration to the timeline, our return to Elpis) as having always been destined to have happened, irrespective of any conscious choices made by the characters. Which is certainly possible, but I wanted to be sure that this was actually the philosophical stance that you were taking. I'm simply observing your starting premises. There's no need to worry about getting pulled into a Wikipedia-sourced internet debate on causality to defend your claims. It is possible to explain the timeline without events being fated to occur, but it requires that Venat gain her knowledge of the future only duriing the events of this expansion i.e. it's not 'all according to plan'.

I think it's worthwhile to attempt to piece together the bits that we have on how spacetime magic works in universe given that it's been used an awful lot in the past two expansions, it has ties to Allag and shard travel, and it at least visually appears to be similar to Azem's own signature magic. I think that there's enough detail from the in-game lore for this to be a hard magic system, and I'd like to know what the rules actually are.

I will argue that the existence of the future doesn’t negate free will. So long as the ability to do otherwise exists and we have the choice to follow our desires, then we have free will.