Avengers – Infinity War: Adventures in Innumeracy

Thanos’ motivations in Avengers: Infinity War make absolutely no fucking sense. Cast as something of benevolent maniac, Thanos wants to kill half the life in the universe to restore “balance”. Putting aside the question of whatever the fuck balance might mean, Thanos seems to be driven by the belief that overpopulation will cause more suffering for life in the cosmos than simply turning half the universe to ash with the snap of a finger. It’s a simple equation: suffering from sudden death < suffering from overpopulation.

But there are a couple of problems with this. While it is true that overpopulation can cause all sorts of problems, it rarely (if ever) directly causes extinction. In natural systems, consumer populations and resource bases fluctuate in cycles of delayed feedbacks.

Very roughly, it goes like this: The bobcats eat too many rabbits, there aren’t enough rabbits to go around, some bobcats starve. Next year, there aren’t very many bobcats to eat the rabbits, so the rabbit population explodes. The year after that, there are plenty of rabbits to go around, so the bobcat population gets a boost. Etcetera etcetera. Of course, most ecosystems have a lot more moving parts. But by and large, that’s how it works, absent some kind of catastrophe. 

Humans – and, presumably, the other advanced civilizations in the Marvel Cinematic Universe – have managed to escape the constraints of fixed resource bases. Instead of following boom-bust cycles, they have engineered their agricultural systems to be more and more productive. That’s why human population growth has never led us into a Malthusian Trap where we exceed the world’s carrying capacity and experience a massive die-off as a result. Granted, our growing population has caused all sorts of ecological and environmental problems, but it hasn’t resulted in the dire human consequences some alarmists have predicted.

Still, it is possible that there could be a point where population growth speeds past a species’ ability to increase its resource base. But even in this scenario, Thanos’ cosmic holocaust doesn’t really solve anything. My humble suggestion is that he really ought to have added a mathematician (or maybe just a person who took some math classes) to his crew of Cradle of Filth cosplayers. This is the problem: A=Pe^kt. What? Gibberish? No: populations exhibit exponential growth, and that’s what that little formula captures. P is your starting population, e is a mathematical constant (an irrational number sometimes called Euler’s number), k is the growth rate, and t is the number of years the population spends growing.

The current world population is about 7.3 billion. So let’s assume that is a number that really bothers Thanos and half that number is a figure that really gets his juices flowing. He wants the world population to be 3.65 billion. Fair enough. But does Thanos think that people are going to quit fucking after his magic snap wipes out half their loved ones? If so, he’s got another thing coming.

If we assume that humans keep breeding at their current modest rate of 1.09% a year, then we can figure out how long it will take before Thanos has to murder half the universe again. That is, 7.3=3.65e^.0109t. We know everything else in the equation (e~2.71828182845) so it’s just a matter of solving for t. Which works out to about 63.59 years.

Every 64 years or so, Thanos needs to come back and kill trillions. In about 256 years, he will have caused twice the suffering he would have caused if he just killed everyone to begin with. If the dude is concerned about suffering, he has an odd way of showing it.

But maybe that’s the plot of Infinity War 2: Tony Stark sits Thanos down and does some math and the whole Marvel Universe comes to an end that would make Franz Kafka feel blue.

Granted, these are gripes about a big purple dude in a movie where a 1500 year old demigod gets zapped by something like a coronal mass ejection for a few minutes to forge a magic axe and survives. So, like the movie itself, just consider this a bit of fun – with a soupcon of criticism for a glaring failure in internal logic.

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