probability predict – A purely probabilistic “doomsday argument” claims the timing of humanity’s end could be inferred from one data point: the total number of humans who have lived. By treating our birth rank as a random draw, the math can produce unsettling time windows for extin
When the numbers first come into view, the argument feels almost rude in its simplicity. Replace apocalyptic predictions built on plagues, asteroids, or wars with something that looks closer to a parlor trick: probability.
The core move is to treat humanity’s end like a statistical outcome you might estimate from where you are in a long sequence of people. The “doomsday argument” leans on a single data point—how many humans have lived to date—and on the laws of probability.
To get the idea across, the logic starts with a blindfold game. Imagine two giant spinning drums. One contains 100 tickets, the other contains a billion. You pull one ticket and it’s number 14. A 100-ticket drum makes that pull plausible. while a billion-ticket drum makes it astronomically unlikely—you’d expect a number that looks like 437. 893. 112. The point is not the exact numbers. It’s the shape of probability when you assume you’re typical.
Now swap tickets for people. The article frames you as roughly the 117 billionth human ever born. Then it asks which story fits better: that you’re an extreme statistical anomaly living at the beginning of a future multitrillion-person era. or that you’re an ordinary human living somewhere near the middle. The uncomfortable answer depends on how several variables are estimated.
If you treat your birth rank as a random selection among all birth ranks. the argument says there’s a 50 percent chance you belong to the middle 50 percent group. Because about 117 billion people predate you. there’s a 50 percent chance those 117 billion ancestors represent between the first 25 percent and 75 percent of all humans that will ever exist. That implies a total of between 156 billion and 468 billion humans.
From there, the math turns into a countdown. The article translates the number of humans into time remaining using a current birth rate of 132 million babies per year. Under that assumption, there’s a 50 percent chance the last human will be born within the next 295 to 2,659 years. It also claims an 80 percent chance this occurs within the next 98 to 7,977 years.
These projections. the argument concedes. may sound like plenty of time—but they’re a tiny fraction of how long humans have been around. It also notes the model assumes a consistent birth rate. “on par with the recent linear growth of the population.” If the model were adjusted to incorporate exponential population growth. it says that would accelerate humans’ demise.
The unsettling part is that doomsday arguments don’t only live on paper. The article points to past predictions by J. Richard Gott III, an astrophysicist. In 1969. he visited the Berlin Wall. which was eight years old at the time. and asked how much longer it would stand. Gott’s single assumption was that the timing of his visit wasn’t special. From that. he estimated a 50 percent chance that the eight years the wall had already been standing represented the middle 50 percent of the wall’s total lifespan. That produced a quantitative prediction: the Berlin Wall had a 50 percent chance of falling within the next 2.67 to 24 years. The wall fell 20 years later.
Gott then applied the same approach to entertainment. In 1993, he predicted bounds for when 44 shows in New York City would end their runs. The article says that by the time his 2001 book Time Travel in Einstein’s Universe: The Physical Possibilities of Travel Through Time went to print. all 37 that had already closed did so within his projected timelines.
The “doomsday argument” is described as being among the main proponents’ ideas connected to astrophysicist Brandon Carter. and the article suggests astrophysicists may be drawn to it because it relies on a principle familiar in their work: the Copernican principle. Named for Renaissance astronomer Copernicus, it argues that Earth is not the center of the universe. Extended more broadly, the principle becomes a warning against assuming we’re uniquely placed in the story of the cosmos. Gott and his peers argue that. all else being equal. we should see ourselves as typical observers rather than special ones—average observers in the middle. not the first or the last.
But there’s no shortage of resistance, and it isn’t just vague skepticism. The article lists rebuttals that go after the assumptions from multiple directions.
One is the reference class problem: the argument depends on what group you treat yourself as a random draw from. Why treat yourself as a random selection among all humans?. Why not include Neanderthals?. If the universe is full of intelligent aliens, why not reason as a randomly selected intelligent being?. And if. in the future. humans become cyborgs and no longer resemble humans. would that count as doom—or would your “human” birth rank quietly become a moving target?. Broadening the reference class. the article says. pushes the expiration date farther out. and that an argument for doom shouldn’t depend heavily on arbitrary boundaries.
Another rebuttal is the caveman objection. If an early human. equipped with a philosophical version of the Copernican idea. wandered into the reasoning around a campfire. the argument might lead them to underestimate how long humanity could last by millennia. If the math looks wrong when applied in hindsight, the critique asks, why should it be trusted for the future?.
Then there’s the self-indication assumption. The article gives a scenario: imagine two possible universes. One will only ever house hundreds of billions of humans. The other will have hundreds of trillions. The self-indication idea says that. knowing nothing else. you should expect to be born in the latter universe because it contains more slots for consciousness. In that framework. the very fact that you exist becomes more likely in the universe with more people. potentially undercutting the doomsday pessimism.
Other critics attack the claim of causal relevance. The article includes a rebuttal that “one’s birth rank can’t end the world.” An asteroid or a nuclear war can end the world. But mathematical reasoning from your armchair birth position can’t. Birth rank. this critique argues. has no causal connection to real dangers and therefore should not count as evidence for apocalypse.
Doomsday proponents, the article notes, have counterarguments to each of these lines. And it adds that both the doomsday argument itself and the proposed refutations come in a variety of forms. The debate. the piece concludes. can get highly technical. with many participants treating the argument less as a forecast of doom and more as a confrontation with what can and can’t be inferred from existence—and where probabilistic reasoning hits its limits.
There’s a human edge to that debate even when it stays mathematical. The question isn’t only whether the end of humanity is near. It’s whether the way we reason about being “typical” can lead us to the wrong kind of certainty—one that feels precise. even when the assumptions under it are still contested. That tension is the engine of the argument, and the reason it won’t go away.
doomsday argument probability theory Copernican principle Gott Berlin Wall prediction reference class problem self-indication assumption birth rank