Why I Don’t Believe in the Butterfly Effect, Part 4
Part 4 of 12: My Central Argument
The butterfly effect is the idea that if you changed just one little thing, then it would set off a chain reaction, such that before too long, the whole world would be radically different. As they say, a butterfly flapping its wings in Brazil creates a tornado in Texas. See Part 1 and Part 2 for more information about the idea of the butterfly effect.
But the butterfly effect is a logical fallacy. The fallacy lies in the assumption that there are only two possible paths of history, and only one node where you can split into two different timelines. That’s not really how the world works.
The universe either is or is not deterministic. The word “deterministic” means different things in different contexts, but here, I mean it in the philosophical sense: if the universe is deterministic, that means there is only one possible way that the events of the universe could unfold. The present determines the future, and the past determined the present. The laws of science explain everything, and nothing can escape them. Once the initial conditions of the universe were decided, then there was only ever one way that the history of the world could have unfolded.
If the universe is not deterministic, that means that the future is currently undetermined. It’s not just that we don’t know the future, it’s that we can’t know the future, because it hasn’t been determined yet. There is some source of indetermination which gives rise to a branching tree of possibilities:
Here, the red branch represents the actual history of the world, the branch that we went down.
Portraying the history of the world as a branching tree does not imply that each branch represents a parallel universe. Personally, I do not believe in the idea of multiple universes. I think there’s only one universe, and that’s the one we’re in now. In my view, drawing history as a branching tree just means that there are other ways that world history could have turned out, but they never happened. Instead, we went down this one particular branch of the tree.
But what might the source of indetermination be? That is, what’s happening at those nodes? Some say it’s quantum physics. They interpret quantum physics as meaning that there are certain nodes in time in which the future splits into different branches of possibilities, with a probability attached to each branch. But I won’t go any further because I don’t know very much about quantum physics. But another theory is that the source of indetermination is human free will: our behavior is not pre-determined, neuroscience alone cannot explain what we do, and at certain points in time, we truly choose how we will respond to our situation. And that’s why there are nodes: each node represents a person’s choice. Thus, we humans collectively choose which branch of history the world goes down.
One further aspect of this theory is that even though we are making choices, there is a probability attached to each possible choice at each node. As such, the history of the world isn’t just a branching tree; it’s a probability tree. And theoretically, you could calculate the probability of any possible future event (for example, the probability that Joe Biden wins the 2020 Presidential Election) just by counting up all the branches on which the event happens, multiplying the probabilities along each branch, and adding them all up.
And once you’ve calculated the probability of some future event, you could plot how that probability varies over time. And it turns out that that is a very useful trick for disproving most arguments based on the butterfly effect. I will explain this in Part 5, Part 7, and Part 8.
(There are some valid questions about this idea of the branching probability tree: what would determine when the next node will occur, whose choice it will be, what the options are, and what the probabilities are for each option? Furthermore, if there’s a probability attached to each possible choice that you could make, is that really choosing? Well, those are questions for another day.)
I personally believe that the universe is not deterministic and that the source of indetermination is human free will. I believe in free will. But that’s just my personal belief. None of these things could ever be proven. We will never know whether the universe is deterministic or non-deterministic. And even if it’s non-deterministic, we will never know what the source of the indetermination is.
But here’s the thing: for the purpose of this argument, it doesn’t matter whether the universe is deterministic or not. If it’s deterministic, then you can quickly prove that the butterfly effect isn’t real, and if it isn’t deterministic, then you can quickly prove that the butterfly effect isn’t real. Those are the only two possibilities, and so we have our result: the butterfly effect isn’t real.
The butterfly effect is based on the premise that the history of the world looks like this:
That is, according to the butterfly effect, there is just one single node, just one single fork in the road. And if we changed what happened at that one node (if we induced just a very small change), then we would induce a very different sequence of causes and effects, and so we would end up on a wildly different course of history.
But that’s not what the history of the world looks like. There is not just one single node. If the universe is deterministic, then there are zero nodes, and if the universe is not deterministic, then there are millions upon millions of nodes. And those are the only two options.
If the universe is deterministic, then the history of the universe is just a straight line:
There was only ever one way that things could have turned out. Thus, if the universe is deterministic, then any alternative history (“if Kennedy hadn’t been killed …”) is purely hypothetical, and therefore, it doesn’t mean anything. If you think the universe is deterministic, then it doesn’t make sense to say, “If that butterfly in Brazil hadn’t flapped its wings, we wouldn’t have had that tornado in Texas.” If the universe is deterministic, then it was pre-determined what that butterfly was going to do, and it was pre-determined that the tornado would happen. There was never any alternative.
Meanwhile, if the universe is not deterministic, then the butterfly effect is false because there are so many other things that could be changed. As previously stated, if the universe is non-deterministic, then the history of the world is a branching tree:
The butterfly effect holds that if we changed just one little thing — like if we had taken the other branch at the circled node — then we would wind up on a completely different course of history. But you can see that that isn’t true because if we had taken the other branch at that node, then, well, there would still be so much yet to be determined. If we’d gone down that other branch, how much would the world differ from what it is today? That would depend on what happened at all the subsequent nodes. As you can see, that one node doesn’t determine very much, because there is still so much that hasn’t been determined yet.
To put it in mathematical terms, that one node does not have a significant effect on the probability of a future event, and therefore, it doesn’t matter very much. I will explain this in more detail in Part 5, Part 7, and Part 8.
In fact, scientists and mathematicians refer to chaos as “deterministic chaos”, because they are well aware of the fact that chaos — that is, extreme sensitivity to initial conditions — is found only in deterministic models. They understand that if you’re dealing with a very non-deterministic model, then changing one little thing doesn’t change everything, because there are still so many other things that have yet to be determined.
(By the way, the arguments I’m making in these essays are not original to me. Scientists would explain these concepts differently than I would, because they think in terms of science, while I think in terms of philosophy, and some of them might not agree with my conclusions. But whether they agree or not, they are already well aware of the fact that non-deterministic systems are usually not chaotic. I am far from the first person to point that out.)
In summary, my central argument is this: the butterfly effect holds that the universe is so chaotic that if you change one little thing, then before too long, you get wildly different results. But if the universe is deterministic, then changing one thing doesn’t change everything because you can’t change one thing, and if the universe is not deterministic, then changing one thing doesn’t change everything because there are so many other things yet to be determined. Those are the only two options. Therefore, the butterfly effect isn’t real.
That is my central argument.
The math and science of chaos theory are correct, but if you think about it in terms of philosophy, it becomes clear that those who promote the butterfly effect are missing the point. They are mathematically correct and they are scientifically correct, but they are not philosophically correct.
In the remaining parts of this series of essays, I will respond to some of the common arguments in favor of the butterfly effect, and I will explore some related concepts. I will also argue that the trick to disproving arguments based on the butterfly effect is to ask the question, “How did the probability change?”
If you would like to see more real-world examples, rather than just philosophical reasoning, you can consult Part 2, Part 6, Part 7, and Part 8, all of which contain many examples.
Other parts of this series:
Part 2: The Butterfly Effect in Pop Culture
Part 3: The Wrong Way to Disprove It
Part 5: Responding to Arguments in Favor of the Butterfly Effect
Part 6: Exceptions (And Why They Aren’t Really Exceptions)
Part 7: Three Wrong Ways to Discuss Alternative History
Part 8: The Right Way to Discuss Alternative History
Part 9: How I Would Interpret Lorenz’s Observations
Part 10: The Butterfly Effect and the Slippery Slope
