Thanos' goal is to halve the population, to reduce demand for resources. The best way to kill half the population is to get all six infinity stones; then you can make half of all life just disappear.

But if you have all six infinity stones, you could just reduce the fertility of all species in the galaxy, so that the population gradually falls to half of its original size.

Why does Thanos prefer murder over birth control?

  • Well, probably, because Thanos doesn't know about that. Or rather, killing half the universe seemed simpler option to him. Also he didn't have our genius scientists to his side. ;)
    – HardikT
    Commented May 8, 2018 at 5:54
  • 3
    If you reduce fertility it will take time to effect
    – Ankit Sharma
    Commented May 8, 2018 at 6:15
  • That would have made a very sad film rather than an entertaining blockbuster. Sad films about low fertility rates include Children of Men. Very sad. Very good. Commented Jul 13, 2018 at 7:56

2 Answers 2


Thanos: When we faced extinction I offered a solution

Dr. Stephen Strange: Genocide?

Thanos: But random, dispassion is fair for rich and poor a like. They called me a mad man. What I predict came unannounced.

Dr. Stephen Strange: Congratulations, you're a prophet

Thanos: I'm a survivor

Dr. Stephen Strange: Who wants to murder trillions

Thanos: With all the six stones I can simply snap my fingers, they will all cease to exist. I call that... mercy.

Dr. Stephen Strange: Then what?

Thanos: finally rest, watch the sunrise on an ungrateful universe. The hardest choices require the strongest will.

The key conversation and relevant parts bolded above.

Thanos wants this to be completely random and dispassionate, and he also wants it to be snap-of-the-fingers immediate.

Aside from not being very interesting as a movie plot point, simply affecting people's fertility wouldn't stop the Avengers. Striking people with infertility also isn't truly random - rich people would end up buying/stealing/making legal the practice of taking babies from poor people.

Also, Thanos is a egotistical, delusional maniac - snapping his fingers and having no visible effects for several years doesn't make him look very powerful.

  • Using the infinity stones, his reduction of fertility could have been as truly random as killing everyone and he would've achieved the same goal. Random, decreased population. There is already child trafficking, kidnapping, and adoption. Nothing changes there. But this would've been a better solution because it would give all of the societies time to adjust rather than their entire economies being suddenly crippled and with half of the population left over to clean up after. And if the stones were powerful enough, it could have been a permanent solution unlike the snap.
    – xr280xr
    Commented Mar 25, 2020 at 18:51

Because Thanos is a "doer" not a waiter. Also that's not how population works. After every major "defertilization" (called war of famine) came huge rise in population. So Thanos just want to put a cap on population for ever. Not to check every 20 years "Oh dudes, you made 10 kids to much".

Also Thanos don't kill those trillions. With full gauntlet he can make them never been born. Not like you will loose your girlfriend. Because one of you would never existed in the first place. And force auto spawning cap into every being soul. Think about humans coming to 5 billions on earth and suddenly whole planet decide that we make one child only is ones die.

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