[This post was inspired by listening to a podcast with Russ Roberts and Brian Klaas on Econtalk, where they discussed Klaas’ new book, Fluke. The title is taken from a quote (provided below) from Will MacAskill’s What We Owe The Future.]
In “A Sound of Thunder”, a science fiction story published by Ray Bradbury in 1952, a company offers their customers the opportunity to travel to the time of the dinosaurs. When they arrive, they have to stay on a levitating path—they are forbidden to make any physical contact with the world of the past. One customer demands to know why, and a guide explains.
"All right," Travis continued, "say we accidentally kill one mouse here. That means all the future families of this one particular mouse are destroyed, right?"
"Right"
"And all the families of the families of the families of that one mouse! With a stamp of your foot, you annihilate first one, then a dozen, then a thousand, a million, a billion possible mice!"
"So they're dead," said Eckels. "So what?"
"So what?" Travis snorted quietly. "Well, what about the foxes that'll need those mice to survive? For want of ten mice, a fox dies. For want of ten foxes a lion starves. For want of a lion, all manner of insects, vultures, infinite billions of life forms are thrown into chaos and destruction. Eventually it all boils down to this: fiftynine million years later, a caveman, one of a dozen on the entire world, goes hunting wild boar or sabertoothed tiger for food. But you, friend, have stepped on all the tigers in that region. By stepping on one single mouse. So the caveman starves. And the caveman, please note, is not just any expendable man, no! He is an entire future nation. From his loins would have sprung ten sons. From their loins one hundred sons, and thus onward to a civilization. Destroy this one man, and you destroy a race, a people, an entire history of life. It is comparable to slaying some of Adam's grandchildren. The stomp of your foot, on one mouse, could start an earthquake, the effects of which could shake our earth and destinies down through Time, to their very foundations. With the death of that one caveman, a billion others yet unborn are throttled in the womb. Perhaps Rome never rises on its seven hills. Perhaps Europe is forever a dark forest, and only Asia waxes healthy and teeming. Step on a mouse and you crush the Pyramids. … Never step off!"
"I see," said Eckels.
Of course, Eckels does step off the path, with tragic consequences for when he returns to the present. (For the Simpson’s version, see the story “Time and Punishment” in the episode TreeHouse of Horror V.)
The immense power of tiny actions—sometimes known as the butterfly effect—isn’t just something for time travelers to worry about. It’s not surprising that big choices—such as getting married, having children, or murdering someone—have big effects. But we are all like Eckels, constantly tromping on the ground and profoundly changing everything that follows.
Fifth Business begins with a malicious young boy, Percy Boyd Staunton, throwing a snowball with a stone hidden inside it at another boy, Duncan Ramsey. It misses Duncan and hits his pregnant neighbor, Mary Dempster, in the head. This causes her to prematurely give birth, and later have a mental breakdown from the trauma. The consequences of the snowball magnify, including the death of Staunton as an adult. He is murdered and his body is found with a stone—yes, the same stone that hit Mary Dempster—placed gently inside his mouth.
The 1998 rom-com Sliding Doors (tagline: “What if one split second sent your life in two completely different directions?”) chooses a more subtle splitting point—the movie breaks into two different realities for the main character (played by Gwyneth Paltrow) depending on whether or not she makes it onto a subway before the doors close.
Our own lives are constantly split by similar fraction-of-second perturbations. Ever just missed being hit by a car when someone changed lanes without looking? (Ever just missed hitting a car when you changed lanes without looking?) How many entire lineages have been wiped out because, at just the wrong moment, someone got a text while driving?
A text that kills someone is an unusual and terrible event, but it is set in motion by other events that are entirely mundane. Here’s a less intense example: A couple of years ago, I took a nasty spill on some ice, injuring my shoulder, and this affected my life over the next few months in many ways. If I left the house just an instant earlier, I most likely would have taken that step differently, placing my foot on the ice a half inch to the right or a half inch to the left, and my injury could have been avoided—or perhaps made much worse. And what might have slowed me down or sped me up? It could have been an email alert, a tweet my eyes passed over, some laughter I heard on the street—the most random and seemingly inconsequential events you can imagine.
Our very existences are highly contingent. Many years ago, a young man was driving to visit his uncle when his car broke down in upstate New York and he had to spend the next two days there waiting for it to be repaired. While there, he met a young woman who was vacationing with some friends. They fell in love, married, and had a child—me. I owe my existence to something going wrong with an Oldsmobile at a very specific place and time.
Along these lines, consider this disturbing passage by the philosopher Will MacAskill. It has to do with sperm.
Consider that a typical ejaculation contains around 200 million sperm. If any of the other 200 million sperm had fertilised the egg that you developed from, then you would not have been born. Instead someone else — with 75% of the genes you would have had — would have been born in your place. A one out of 200 million event involves extreme luck. So, much as I’m sure you don’t want to think about such things, even if your father’s ejaculation had occurred milliseconds earlier or later, it would almost certainly have been a different sperm that fertilised your mother’s egg. And so any event that affected the schedules of your biological mother and father on the day that you were conceived, even if only by a tiny amount — such as a longer line at the supermarket, or an additional car ahead of them on their way home from work — would have had the result that you wouldn’t have been born.
… every year, like clumsy gods, we radically change the course of history. For example, if you live in a city, then by choosing to take public transport to work and back, rather than drive, then over the course of a year you will ever-so-slightly impact the schedules of tens of thousands of people each over hundreds of days. Statistically, it’s likely that, on one out of those tens of thousands of person-days, the person you impacted had sex and conceived a child later in that day, and you affected, ever-so-slightly, the timing of that conception, changing which sperm met the egg, and changing who was born. That different person will then impact the schedules of millions of other people, changing what children they have, and so on, in an identity cascade. … Wars would be fought that would never have been fought; monuments built that would never have been built; works of literature written that would never have been written. All because of your choice of whether to drive or take the bus.
If you’ve read this far, or even glanced at an announcement of this post on Twitter, nothing in your life will ever be the same. Some of you (as well as the people you will later encounter, and the people they will later encounter) who would have had boys will have girls, and some who would have had girls will have boys. Some will die younger as a result of this post; others have been saved from terrible injuries.
If you’re frustrated at the one-way nature of all this—here’s me in my study in Toronto messing with your life—you can easily return the favor. Put something in the comments. I’ll read it, and the seconds that are required for this will cause a tiny change in my life, one whose effects will grow and grow and grow. I’ll be your clumsy god and you’ll be mine.
One implication here is that we should give up on all plans of the “travel through time, kill Baby Hitler, make the world better” sort. You can’t count on a positive effect. Books and movies have figured this out. Stephen King’s 11/22/63 involves a time traveler who rescues Kennedy from being assassinated with the hopes of ending the Vietnam War earlier. In the movie The Flash, our hero goes back in time to save his parents. In each case, the mission is successful—but when the characters return to the present, they discover that there are terrible unintended consequences.
Given that the world right now could be a lot worse—we’re not all dead, after all—I would support a moratorium on all time travel to the past.
Here’s a more troubling implication. The butterfly effect makes it impossible to gauge the overall effect of any single action—or any single life. A good friend of mine once told me that what he wants most out of his life—what would give it meaning; what would give him a sort of immortality—is to make the world a better place after he’s gone. And so he tries to be a good person, and he is a good person, changing the lives of many people (including me) for the better.
And yet. Perhaps one day my friend will say something in a lecture that motivates a student to look something up when she gets back to her dorm. And, because of such an innocuous and unintended act, something else of greater significance happens years later—perhaps a skilled diplomat misses her flight to an important summit or some sensitive child is the victim of a prank at school—and then something else happens and then something else happens and then the world ends. And this is how my friend will have made his biggest difference.
In Fluke, Klaas emphasizes that alongside this chaos, there is order, control, and causality. You can plan for the short term (to meet a friend for coffee later in the day) and you can plan for the long term (to get married at a specific time and place a year from now), and, for the most part, these plans succeed. If we are wise, we try to prepare for some degree of randomness. Heading to a movie, I’ll leave with plenty of time to spare so that if the sliding doors of the subway close as I’m approaching, I’ll just get the next one. I know from the Gwyneth Paltrow movie that my life will never be the same, but I still retain some control over my immediate fate—I’ll be there in time for the previews.
This control makes morality possible. We try to do good things for others, and, though our acts sometimes go awry, we really do often succeed. Though there is always the specter of unintended consequences, it would be madness to deny that the world is better off due to thoughtful acts of kindness.
But our powers as clumsy gods should make us humble. We should be less confident that, in the long-term, our acts have anything like the effects we want them to. And we should appreciate that, for better or worse, we cannot anticipate how certain events, even those that seem obviously beneficial or obviously harmful, will change our own lives.
A Taoist story (slightly modified from here) nicely illustrates this point.
There was an old farmer who had worked on his crops for many years. One day his horse ran away. Upon hearing the news, his neighbors came to visit. “Such bad luck,” they said sympathetically. “Maybe,” the farmer replied.
The next morning the horse returned, bringing with it three other wild horses. “How wonderful,” the neighbors exclaimed. “Maybe,” replied the old man.
The following day, his son tried to ride one of the untamed horses, was thrown, and broke his leg. The neighbors again came to offer their sympathy on his misfortune. “Maybe,” answered the farmer.
The day after, military officials came to the village to draft young men into the army. Seeing that the son’s leg was broken, they passed him by. The neighbors con- gratulated the farmer on how well things had turned out.
“Maybe,” said the farmer.
...all due apologies to the civilisations that were wiped out by my writing this:
It's frustrating how often I discover my ideas have been plagiarised by famous thinkers.
You know, I independently invented Laplace's Demon when I was 16. Then I found out some French guy articulated it 200 years ago.
When my daughter was born, in 2019, I thought: "Well, this is the limit to how far I can go back in time. Any earlier and I'll be risking her perfect existence". Now you tell me Will McAskill is claiming the credit for that.
Maybe. Or maybe one dead mouse is just noise. It doesn't follow that any minor event can have enormous consequences. It's possible that big events are over-determined. The butterfly effect is misunderstood. It wasn't coined to illustrate how small effects can have large consequences, but that highly dynamic systems can be so sensitive to initial conditions that we can't know if they had an effect nor track the changes. Hurricanes are caused by large interactions between water and air currents. One butterfly won't make a difference. Similarly, there are broad social/economic/political trends that bring about historical events regardless of the actions of individuals (or mice!). We usually say that WW1 was initiated by the assassination of Archduke Ferdinand, but Europe had been on the brink for years. It’s impossible to say what would have happen otherwise, but there probably still would have been a war.
There's also something funny about the idea that you may not have come to exist because of some random sperm event (or sliding door or whatever.) It's true that you, specifically, would not be here, but someone else might be, here or on another blog making similar observations.
I've never been able to properly express what I feel is the misstep here, but it has something to do with the idea that you trying to compare existence to non-existence. But non-existence is not a property that you can or can't have - it's not a property at all. You didn't wonder about your existence before you were born, and you won't wonder about it after you are dead (unless: afterlife).