Avoiding the butterfly effect and stargate

[StargateMillennium]

This is something I never understood in stargate is Sam's constant desire to avoid the butterfly effect. For those who aren't familiar with it, it essentially says a small change in the past can cause drastic changes in the future. Normally, a time traveler would want to avoid the butterfly effect because they intend to return to their original time and will have to deal with the consequences. When SG1 got sent back to 19 something or other, they wanted to avoid butterfly effects because they intended to return to their original time.

But then you have instances where O'Neill sent his message to warn about the Ashen. Or when Teal'c got sent back in time in the Unending episode. They had to be vague about everything. Why? Now you want the butterfly effect. And if it was that bad, why is it ok to have instances like when Shepard went to the future or when the Desinty crew viewing a future of their own deaths? Those things were chalk full of details.


Why is it so important for them not to know a possible future? It's already been changed and they don't intend on seeing it.

[Xaeden]

These types of shows tend not to be great when it comes to depicting time travel. I think they rely a lot on the assumption that viewers are generally so confused by the concept that rather than try to understand it they just accept they're in for confusion when a time travel episode comes 'round. As a result, writers think they can more readily throw in certain things that service their storytelling aims but don't follow any sort of logic.

In this case, from a writer's perspective you don't really want your main characters to be able to have entire dossiers that will spoil future adventures. You just want to resolve this one plot point that you came up with for this one episode, which is to prevent the timeline from changing or reoccurring. Inventing a pointless rule is a quick and dirty way to do that, particularly because it seems like it would make sense to people since they're used to hearing it in a context where there is a bit more logic to it. In Teal'c's case, though, they try to play it off as Teal'c just being Teal'c...

VALA
Oh, come on, it's driving me insane! You know, technically, there would be no danger of creating a time paradox, because we've already changed future events. You would not be altering the future by telling us about something that's not gonna happen anymore!

TEAL'C
Then why do you care?

VALA
Fifty or sixty years? Something interesting must have happened. Obviously I hooked up with someone.

But really, the writers just didn't want Vala and Daniel to know about their relationship. It's meant as a tease for fans, not something that they would logically have to address whenever the two did their whole sexual tension bit.

Much the same goes to how the butterfly effect is portrayed, overall. If it were being depicted realistically, nobody who was alive in the original timeline's 2000s would be alive after Sg-1 went back to ancient Egypt. Just being there and interacting with the world would have a dramatic cascading effect on who met and reproduced with who. But why spend money casting new people who have no connection with the audience in order to show that when you can just pretend that the butterfly effect means all the same people will be born and/or certain old characters who died will be alive again, but they will somehow have different personalities?

It's particularly worthwhile because audiences not only seem to enjoy it but they seem to still buy that it makes sense. Whenever you see the 10% brain myth used in a story, there will be people on the internet bashing a work of fiction for still relying on that old trope. However, the "Would you kill Hitler if you could go back in time?" question is as popular as ever and almost nobody mentions that the time traveler who did that would be a bigger mass murderer than him at this point. Assuming, of course, if it were possible to change time, which is common a debate that comes out of that question, but that's usually as far as it goes.

[Tilarta]

"The future is not set in stone, there is no fate but what we make."
I assume in sci-fi, the only concern is not changing the past, as the future hasn't happened yet, they're less invested in making sure that happens as intended.
Especially considering since that timeline tends to be really awful!

Of course, there is McKay rewriting history with his message to the future, but maybe he didn't do that "officially".
I got the impression they only approved the project because they thought it wouldn't work at all.
And to stop him bugging them about making it happen.......

It did have a minor effect in Stargate SG-1 though, after a history reset, O'Neill states "there are no fish in his pond", followed by one jumping above the surface.

Realistically though, if time travel was invented, someone would then make sure there was a time police to make sure nobody altered history.
And presumably, that organisation would have a method of protecting themselves from temporal incursions so as to be aware of the changes and to change them back.

For example, if someone goes go back in time to remove a despot, they follow that person back and arrest the infractor before they can do it.
Also, being time travel, they could just go back to slightly before the infractor arrives and be waiting for them the moment they appear.

[Xaeden]

Realistically though, if time travel was invented, someone would then make sure there was a time police to make sure nobody altered history.
And presumably, that organisation would have a method of protecting themselves from temporal incursions so as to be aware of the changes and to change them back.

For example, if someone goes go back in time to remove a despot, they follow that person back and arrest the infractor before they can do it.
Also, being time travel, they could just go back to slightly before the infractor arrives and be waiting for them the moment they appear.

Well, realistically, what you would want to do is go back to before they time traveled and stop them from time traveling in the first place. Stopping them after they've gone into the distant past is a pulp concept that writers use for entertainment value, but would actually massively mess up the future in and of itself if we're dealing with a form of time travel where things can change. The closer you are to the present, the least you will notice the consequences of your actions. Say you go back to 10,000 years ago and do nothing but detain another traveler. The process lasts maybe a few minutes and there's nobody around. Doesn't matter; you will not return to a future where you or anyone you ever knew was born.

[thekillman]

However, the "Would you kill Hitler if you could go back in time?" question is as popular as ever and almost nobody mentions that the time traveler who did that would be a bigger mass murderer than him at this point.

I blame it on a ****ty understanding of history. If you want to prevent Hitler from doing what he did, go a bit further to a country called serbia and prevent a guy called Franz Ferdinand from getting shot. You could prevent 2 world wars that way, potentially. Although it would also cost an immense amount of modern progress, including modern takes on ethics, and could doom the human race to a hot nuclear war.

Why is it so important for them not to know a possible future? It's already been changed and they don't intend on seeing it.

I think it's simply that you want to make a small, targeted change that alters the future in one, specific way. Creating more changes could cause a cascade of unwanted side-effects, and potentially ruin what you wanted to change in the first place.

Besides, the act of telling someone about a future event in itself is changing history. Can you be certain you'll react in the same way, knowing some major event is gonna happen? And what if, due to small changes, those events happen earlier or later? And how long will people keep believing in future messages? Giving information on future events could change these very events, invalidating the information you give. Which could cause questions on the validity of other, perhaps more important questions.

In the case of the Aschen, being told of their danger might cause military high command to want to assess the threat, and so unknowingly alert the Aschen in other ways (say, they send a probe). The existence of the letter ensures that no matter what happens, Earth can always ask the Aschen for their home-adress and learn immediately that stuff is wrong. They can then launch their own investigation into why. No need to tell the full picture.

[Xaeden]

I blame it on a ****ty understanding of history. If you want to prevent Hitler from doing what he did, go a bit further to a country called serbia and prevent a guy called Franz Ferdinand from getting shot. You could prevent 2 world wars that way, potentially. Although it would also cost an immense amount of modern progress, including modern takes on ethics, and could doom the human race to a hot nuclear war.

Another problem is that preventing war is not often something that can be done in a targeted way. Killing Hitler wouldn't change that the economic and territorial restrictions put on them at Versailles made it likely that someone would come to power who would seek to restore Germany through war. Although, perhaps this other person wouldn't be so inclined to demonize and target Jews, to the same degree or at all. On the other hand, it might also lead to someone who better handled relations with the Soviets, rather than pushing them into common cause with the British, resulting in Germany being distracted on their Eastern front at a time when they otherwise would have only had the United Kingdom to contend with. And, yeah, the whole nuclear situation could easily have played out very differently.

Same with Ferdinand. Alive or dead, it doesn't change that Germany was looking to prove itself and had achieved military advances that made it think it could quickly win a war with its neighbors, it doesn't change that there were all these secret treaties, it doesn't change that nationalism was so strong at the time that others similarly believed their country could quickly win a war, etc.

A lot of lessons came out of those wars; the end of secret treaties, the European Union, the United Nations, the U.S. move away from isolationism, the recognition that building up a defeated enemy was better than tearing them down (at least in the West; the Soviets had different ideas), the horror of large scale modern warfare, etc.

[Tilarta]

To be honest, I doubt someone taking one step into the past before being arrested will change anything.
Large changes will need to be made, like destroying a building or accidentally ending someone's life which will prevent them having a descendent who would change the course of history.

As regards why they have to catch them in the past, two possibilities occur to me:
1. They have to be caught in the act of committing the crime, as in, you have to see them in the past. That is, unless owning a time machine is a criminal offence in itself. Otherwise they could just claim that the time machine exists for "research purposes", to study the past via a time window.
2. They don't know where the time machine is, so it's easier to go back to the place where history is altered.
Star Trek Online has a plotline about that currently, about a species committing temporal vandalism on a grand scale because they feel they should be allowed to rewrite history to their benefit. They mentioned that the Na'kuhl have some kind of shielding device that prevents chronometric sensors from detecting the portal when it is activated. Also, they enable a timed self destruct when they use it so the computer records can't be recovered by enemy forces.
So the only way to stop the Na'kuhl agents is to catch them in the past.


As regards World War II, it was won because the enemy forces had an irrational leader who would make illogical decisions.
If someone removed that leader, someone competent might take over and when the time traveller would return to a future where Germany conquered the world.
Oops.
Now the time traveller has to go back again and stop themselves from doing it in the first place...

[P-90_177]

This is something I never understood in stargate is Sam's constant desire to avoid the butterfly effect. For those who aren't familiar with it, it essentially says a small change in the past can cause drastic changes in the future. Normally, a time traveler would want to avoid the butterfly effect because they intend to return to their original time and will have to deal with the consequences. When SG1 got sent back to 19 something or other, they wanted to avoid butterfly effects because they intended to return to their original time.

But then you have instances where O'Neill sent his message to warn about the Ashen. Or when Teal'c got sent back in time in the Unending episode. They had to be vague about everything. Why? Now you want the butterfly effect. And if it was that bad, why is it ok to have instances like when Shepard went to the future or when the Desinty crew viewing a future of their own deaths? Those things were chalk full of details.


Why is it so important for them not to know a possible future? It's already been changed and they don't intend on seeing it.

Let me deal with the specific instances you mentioned.

The original intent in 2010 was to change the past to ensure that Earth never made contact with the Aschen. There are however several things to consider with this. First of all is the fact that Sam in that future was in a relationship with that diplomat (I forget his name. I haven't seen the episode in years). Now given his involvement from the outset of formal relations with the Aschen we can possibly assume that said diplomat was already shortlisted to be involved with the Stargate Program should such an event take place. Not just with the Aschen but with advanced races generally. This is backed up by how he was likewise involved later when SG-1 ended up encountering the Aschen despite their best efforts. Now if Sam remained vague in the message she would be aware that with luck the SGC would simply lock the planet out of their systems and nothing else would change. However a more detailed message such as something like "There is an advanced alien race on this planet who are dangerous." or such may prompt a change or re-think in policy at the SGC, said diplomat might be reconsidered for one with a different level of experience and Sam might never meet him. Now you might argue that she wouldn't remember, and that is true but at the same time why not allow the possibility for the past version of her to still find the same kind of happiness?

It's a similar sort of thing for Teal'c in Unending. Take Vala and Daniel for example. They came together as a couple in a very natural way after a lot of dancing around each other. If Teal'c revealed that then it might prompt them to do the same, or it might force them together before they were really ready or they simply might not be able to make a relationship work in the same way under different circumstances. Teal'c is wise enough to recognise this and spare them from that potential pain. If they are still meant to be then they will find their own way too it. Plus besides that his experiences in the time stop were intensely personal. He watched his friends grow old, and in Landry's case die. I doubt he'd want to share that anyway.

[Xaeden]

This is indeed a difficult concept to wrap one's brain around and it doesn't help that mainstream fiction doesn't usually depict it, leaving people to have to conceptualize it on their own. Star Trek is a big part of the problem, in my opinion; they're responsible for popularizing many of the altered personality tropes that we see in time travel/alternative reality fiction and they insist on switching back and forth between different time travel theories even though there's no reason why sometimes the future would be changeable and sometimes it's predestined.

Anyway, here's an aid to help you think about the butterfly effect:

Does any particular moment where you interacted with a wild animal stick out in your mind right now? Try to think of one where you know your presence caused the animal to react somehow. I'll give you an example of mine: A couple of years ago, I was sitting by a creek and I saw a squirrel walk by. On a whim, I yelled; Hi, squirrel!" causing the squirrel to panic and, instead of continuing into the open field he had been walking into, he darted back into he woods. Later, I told someone about this and how it took me off guard because I was used to interacting with city squirrels, who practically ignore you. My small decision to speak in that moment, had a ripple effect with unforeseen consequences that will now lead to different individuals living, dying, and being born.

First, it caused the squirrel to do something differently. Now he has to look for food at a different time in a different place. Maybe if I did nothing it would have led to a train of events where he got attacked by a predator. Maybe because I said something he simply will not meet the same squirrel that he originally would have reproduced with and because of that his descendants now will not exist to be in the right place at the right time to nest in someone's attic and drive a guy crazy over a period of time. Maybe this person leaves them alone and is woken up early by their movements and regularly has to stop what he's doing to bang on the ceiling.

That changes how that person interacts with the larger world. Perhaps he's not on a certain street at a certain time when he otherwise would have bumped into someone and caused an argument that saved the bumpee from being in the wrong place in the wrong time to get hit by a car later on, allowing this bumpee to be in the world to find a mate to reproduce with. That would not only lead to different children being in the world, it would also remove whatever children would have come out of a relationship with another man that woman would have otherwise met. And because the person she originally would have had children with is now single, he will likely have children with someone else, who also will be picking him over the man she originally would have chose. It goes down the line like that, leading to many, many people who find different individuals to reproduce with because the person they otherwise would have had children with met someone else first.

Second, it has had an impact on my life. In addition to initially telling someone about it and nudging them on a slightly different course because of it, I think about it from time to time instead of thinking about other things. Maybe I would have otherwise remembered that I needed to buy something, leading to me making an Amazon purchase earlier than I would have, which, among other things, involves a course correction for my UPS driver. Now he has to come down my street, which means there are people in cars who are making different driving decisions because of this and then doing things differently in aspects of their lives based on their altered driving experience. For example, maybe someone will now enter a supermarket at the same time someone else is, instead of seconds later. What possible ripples could that seemingly noteworthy interaction cause?

Then, of course, there's the fact that I am taking the time to write all of this. Sure, I would maybe still be in a position to have written about another example for you, but there is a certain length of time that it takes me write out about the consequences of this particular example and a certain thought process that it entails. How would my time be spent differently if that never happened? Would I end up checking my email and replying to someone minutes earlier/later, prompting them to break from what they were doing? Maybe I'd be doing the dishes by now and sending dish water down into the sewer that will kill an insect who otherwise would have lived and somehow influenced someone's life.

At the start of this post, I asked you to imagine an interaction with an animal. How about you now try to narrow that down and think about an interaction with a particular insect? Do you think those interactions are completely trivial or in any way led to you doing things differently? I can tell you about dozens of cases where I spent whole nights trying to avoid and track down specific mosquitoes that happened to get into my house and would regularly bite me. What could I have been doing instead? Maybe reading a book that I could have then talked to someone about or writing a post like this to someone on the internet and, in the process, diverting dozens of people to either reading it or rolling their eyes at the length.

Third, it is now having an impact on you. Maybe you chose to sit down and read this all, maybe you gave up part of the way through, but wouldn't have if I told you a different story. How does that change your subsequent interactions with the world and how do those changes alter the interactions of those you interact with?

A specific living being being born is the result of one sperm and one egg coming together at exactly the right moment. A slight change in position or timing and you have a different sperm doing the fertilizing or the egg not being fertilized at all. It doesn't matter if we're talking about a human or a non-human animal, that is going to have significant consequences on a whole host of births and once different individuals start being born they create more interaction based ripples, including prompting the creation even more offspring that wouldn't have otherwise existed, leading to more and more ripples.

The examples I have provided have been quick links between action and consequential effect, but in many cases there will be a lot of steps in-between a person bumping onto someone on a street and someone dying or living because of it. So if it helps, think of something major that you can trace back to a small event, but keep in mind that there are many little moments that are seemingly meaningless, but actually add up to create every big event that occurs and every big event has an impact on other events, large and small.

To go back to someone spending a few minutes in the past apprehending a time bandit type in a remote location, forget the weather patterns aspect of the butterfly theory because that's harder to visualize; can you be sure that no insect or animal was around and did something differently because of this? Just a little bug now being in a different location at a different time could cause a bird to see that bug and make a course correction to eat him. That would lead to many, many different course corrections of other animals, including course corrections that affect reproduction.

Then there's the issue of the things left behind; footprints, scents, broken twigs, and stepped on plants. Animals coming onto the scene later would react differently to these things. Maybe a human and a dog are supposed to pass by later and now, instead of going straight, that dog goes off to where these time travelers were and sniffs around in a circle. Because of this he wasn't in the right place at the right time to catch a rabbit for his human, leading to there not only there being a rabbit around to continue to interact with the world, but this primitive human having to either come home without any food and his family suffering the ramifications of that or having to spend more time in the woods until he and his dog find another animal, not only taking this other creature out of the food chain instead but prompting different interactions and life choices due to his returning home at a different time; interactions/choices for him, his family, everyone his family interacts with, and so on and so forth.

Of course, it's also worth noting that the scenario you described tends to be more dramatic with people running around in a populated area, talking to people while looking for clues, shooting at each other, etc.

[Tilarta]

Future Leo and Five have comments to make on this subject.
They said something like small changes will be compensated or corrected to keep history on track.
And keep in mind Future Leo was changing his past to make a different future happen, so he knew what he was talking about.

It ended up kindof complicated though, he got the future he wanted, but his personal timeline was altered, so Present Leo had to set it back on track.
Thereby creating an alternate personal timeline that conflicts with the one that originally happened, although it achieved the same result (theoretically).
And somehow, Future Leo remembers the original timeline and his previous personal timeline even though both have been rewritten.

"Time travel, it's a cornucopia of disturbing concepts."

[Xaeden]

Yeah, that's a non-scientific destiny based concept in fiction where there is some sort of overarching force controlling things. For that to to be possible, someone or something needs to either control the actions of individuals (temporarily or in full) or needs to be able to make things happen without humans noticing (objects appearing/disappearing, babies being given to people, etc.). Some fiction likes to just say it's the universe course correcting, without elaborating. Other fiction will imply or definitively attribute this to a god figure.

In either this case this falls under the purview of my clarifying statement that the butterfly effect only applies "if we're dealing with a form of time travel where things can change."

[Tilarta]

Well, there are two possible ways this can be approached.

The first is that the "time travel enforcers" have a way to isolate themselves from temporal changes, so when history is rewritten, they notice it happened and change it back.

In First Contact, being inside the temporal wake of a Borg timestream shields the Enterprise-E from being erased and they notice the planet nearby has been assimilated when it wasn't before.
So they follow the Borg sphere into the time portal and change history back.
Seven called it a predestination paradox, stating that attempting to alter history will just cause a chain of events that causes it to go back to the way it was before.

Enterprise expanded on this further, two Borg from the sphere survived, revived by a Starfleet science team (who they promptly assimilated), then they assimilated a civilian vessel/crew and sent a transmission to the Borg Collective informing them of a civilization suitable for mass assimilation.
It took two centuries for the transmission to reach the Delta Quadrant, as the carrier wave wasn't powerful enough and they responded by dispatching the Borg cube which encountered the Enterprise-D and assimilated 18 of their crew members, thereby learning of their new target directly.

The second is that there's temporal based entities who keep the integrity of linear flow intact and when they catch you throwing rocks on the tracks to derail the time train, they step in to correct the changes.
In Star Trek, this seems to be the role of the Prophets, they exist outside of time, seeing past, present, future and alternate timelines as one plane of reality.
When someone attempts to mess with the timeline for their own personal gain, well, it's best to hope they don't exact a heavy punishment for temporal vandalism.
Zek learned this the hard way, he wanted to know the future for financial gain and in response, they reprogrammed him to be completely selfless and generous.
Star Trek Online suggests even the Q fear the Prophets:

[Xaeden]

Seven called it a predestination paradox, stating that attempting to alter history will just cause a chain of events that causes it to go back to the way it was before.

This is a slight misrepresentation of the predestination paradox. The predestination paradox actually means that the time traveler's actions predate him/her (hence the name). The basic idea is that history cannot be changed because whatever has happened will always happen, so when the Enterprise and the Borg Sphere went back in time they were fulfilling events that had already taken place. There is no beginning the loop where events played out without time travelers in the past; Picard and company always existed in a timeline that was based on the actions he would come to take in the past to help Cochrane get his warp drive operational. (Cochrane never did this on his own and the Borg never weren't there.)

So they're not doing something different that, for some cosmic reason, is causing events to play out as they did previously anyway; they're doing exactly what they have always done, leading to everything (including their own actions while in the past) happening as it always was supposed to.

In this case, the time travelers were unaware that they had been to the past previously and the predestination paradox was at play, but in other works of fiction a time traveler might very much be aware of all this and try to subvert the predestination paradox anyway. The problem; they've always fought to change time with the knowledge that they weren't able to do so previously, so whatever they do will be what they've always done.

The number one difficulty that viewers have to understanding this concept is that they think there must be a starting point where the time traveler existed in a timeline free of time travel, but there isn't. Again, a time traveler's actions in the past have always predated/predestined the act of time travel itself.

[Tilarta]

Presumably, there had to be some point where history flowed as it did without intervention.

For example, Zephram Cochrane says nothing to Kirk about having met Picard or the Borg.
Considering the level of the threat the Borg represent, an early warning would have been useful!

From Deep Space Nine, Sisko's image taking the place of Gabriel didn't happen until after he went, otherwise everyone would have been commenting on that fact long before he went there.

And in Seven of Nine's case, she did a minor rewriting of history to make sure a chain of events that lead to Voyager's destruction never happened, by doing exactly what I mentioned, sending someone to the exact point a temporal subversion begin in order to make it all cease to happen.
Although it did have the side-effect of Seven and Janeway remembering all the alterations both of them made to their past.

And then we have Future Janeway completely rewriting history to change it for the better.
Given that she lived through 25 years of the bad version, it's fairly clear she wasn't there the first time around at all.

[Xaeden]

Presumably, there had to be some point where history flowed as it did without intervention.

Like I said, this is the biggest problem people have with understanding the concept but, no, the fundamental principle behind it is that we're dealing with a casual (or closed) loop in which things end where they begin. I get it, it tests your traditional understanding of logical reasoning but keep in mind that that is what a paradox is supposed to do; a paradox is a statement that seems false, but could also be true. Essentially meaning that it's going to be self-contradictory, but can nevertheless not be dismissed.

I've been down this road countless times before, and I've often had difficulty trying to get people to visualize it properly by describing it to them textually. It therefore might help if you search for a Youtube video where someone explains it with visual aids and/or check out some predestination paradox fiction and then get involved in online discussions about it. The movie, 12 Monkeys is a great one.

For example, Zephram Cochrane says nothing to Kirk about having met Picard or the Borg.
Considering the level of the threat the Borg represent, an early warning would have been useful!

Let's be real: Cochrane met Kirk before the idea of the Borg and time traveling to the 21st century ever existed. Therefore, at best, you would be pointing out a flaw in the idea to retroactively reuse Cochrane via a form of time travel that is predestined. A writer can fail to properly depict a particular concept. That doesn't change what the concept is; the predestination paradox is not the predestination paradox if there's a beginning to the loop.

That said, fiction usually justifies the "not telling" bit by making characters afraid to change the timeline. Even though they can't change the timeline because, if they told someone, they always would have told someone, they don't always know that, leading to them internally debating what the best thing to do in certain situations is to make sure that things work out properly.

Another method is the "nobody would believe me" angle, which is essentially what happens in Cochrane's case. Per Enterprise, he did try to tell people, but upon being met with disbelief he settled into the idea that it was pointless trying to warn people, thus justifying why he didn't bring it up to Kirk later on in his life.

ARCHER: There was something familiar about all this, but I couldn't put my finger on it until I find this speech Zefram Cochrane made eighty nine years ago. When I was a kid, I read everything I could about him. It took me a while, but I finally found it in the database. He was giving a commencement address at Princeton when he started to talk about what really happened during First Contact. He mentioned a group of cybernetic creatures from the future who tried to stop his first warp flight when he was living in Montana. He said they were defeated by a group of humans who were also from the future.
T'POL: As I recall, Cochrane was famous for his imaginative stories. He was also known to be frequently intoxicated.
ARCHER: No one took him seriously, and he recanted the whole thing a few years later. But you have to admit, there are similarities.

-Regeneration

From Deep Space Nine, Sisko's image taking the place of Gabriel didn't happen until after he went, otherwise everyone would have been commenting on that fact long before he went there.

Instead of looking that episode up to confirm what happened there, let me remind you what I said previously:

"Star Trek is a big part of the problem, in my opinion; ... and they insist on switching back and forth between different time travel theories even though there's no reason why sometimes the future would be changeable and sometimes it's predestined."

There are absolutely times in Star Trek where the future in changeable and not predestined, but there are also times where it is. It's a product of all the different writers who have worked on the franchise over the course of hundreds of episodes. Rather than picking a time travel concept and applying it consistently throughout the franchise, a writer would come in and use whatever they thought would work best for their individual story. Instead of retconning it, Star Trek embraced it and provided some vague dialogue from Seven that there is always uncertainty with time travel so they don't know if they will get caught in a predestined loop or be able to change things when they time travel, which allowed them to continually switch back and forth between different theories on an episode-to-episode basis.

Stargate has a similar issue in that they first used the predestination paradox in "1969" but then decided that it was a boring way to tell repeated time travel stories so they replaced how time travel works in-universe and then have consistently used that form of time travel without ever once mentioning the predestination paradox again. Essentially, they retconned it away.

Star Trek, on the other hand, has a habit of canonizing inconsistencies like this. Don't let it confuse you. This and the Voyager examples you provided are a Star Trek consistency problem, not a problem with the predestination paradox or an attempt to pretend that there have not been instances where the predestination paradox occurred elsewhere in Star Trek. If you want to learn about how different time travel theories work, it's best not to mix and match Star Trek time travel examples. Either view them individually or look to works of fiction that consistently use a single theory.

Below is dialogue from that Seven of Nine time travel episode. As I mentioned above, you will see that they talk about different methods of time travel being possible. You will also see it being said that there is uncertainty regarding which one will apply to Seven in her specific situation. The Pogo Paradox, by the way, is apparently supposed to be the in-universe name for the predestination paradox. At least for that episode; I doubt future writers will remember and reuse it.

DUCANE: Let's see how much you've assimilated. The Dali paradox.
SEVEN: Also known as the Melting Clock Effect. It refers to a temporal fissure which slows the passage of time to a gradual halt.
DUCANE: The Pogo Paradox.
SEVEN: A causality loop in which interference to prevent an event actually triggers the same event.
DUCANE: Excellent. Can you give me an example?
SEVEN: The Borg once travelled back in time to stop Zefram Cochrane from breaking the warp barrier. They succeeded, but that in turn led the starship Enterprise to intervene. They assisted Cochrane with the flight the Borg was trying to prevent. Causal loop complete.
DUCANE: So, in a way, the Federation owes its existence to the Borg.
SEVEN: You're welcome. The Seven of Nine paradox.
DUCANE: I beg your pardon?
SEVEN: How we do know that my presence on Voyager will not alter the timeline?
DUCANE: You know, you've asked me this every time.
SEVEN: What's been your response?
DUCANE: That uncertainty is part of the equation. We don't know what's going to happen.
SEVEN: I don't enjoy uncertainty.
DUCANE: Neither do I. But I trust Captain Braxton's instincts, just as you trust Captain Janeway's.