How can Thanos be sure that

wiping out half the life in the universe

will undoubtedly rejuvenate the remaining life and that the finite resources in the universe will be sufficient for the remainder of sentient life? If he knows for certain, it makes sense that he would choose to bear the burden but if not, the act is just a tremendous gamble.

  • 11
    +1 for an interesting question, getting the tagging conventions 100% right and an awesome display picture! Welcome to Sci-Fi and Fantasy, and I'm sure your question will get an answer shortly (UTC Mornings are usually quieter).
    – Edlothiad
    Commented May 7, 2018 at 7:29
  • Related if not close dupe - scifi.stackexchange.com/questions/186626/…
    – Paulie_D
    Commented May 7, 2018 at 8:02
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    Possible duplicate of How did Thanos (or anyone) know this?
    – SH7890
    Commented May 7, 2018 at 9:46
  • 1
    @SH7890 Not a dupe this asks how did he know doing what he did would work, the dupe asks how did he know he could do what he did.
    – TheLethalCarrot
    Commented May 7, 2018 at 10:06
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    @Paulie_D related, not dupe. That one is asking why he didn't try actions without killing. This one is asking whether he could be certain that eliminating half a population would lead to prosperity.
    – Edlothiad
    Commented May 7, 2018 at 10:13

4 Answers 4


During the film, we see that Thanos doesn't plan to kill 50% of the people for the first time once he gets all the Infinity Stones. He's done it many times before, on many planets. Specifically, Gamora was from a world that Thanos conquered, and he killed half the people there.

During the events of Infinity War, Thanos tells Gamora that the people who live on her home planet now don't know hunger, and are all really well off because of his actions. He also points out that his own home planet, Titan, didn't listen to his warnings and is now a wasteland.

So it appears to me that Thanos has, on probably more than one occasion, seen what happens if he kills 50% of the population, and what happens if he doesn't. We don't know how many trials he ran before implementing his universe-wide plan, but it's not like he's never done it before.

  • I just now noticed that Muspelmegir posted almost this exact same answer as a comment to another answer. I guess that's why they say not to post answers as comments. Commented May 7, 2018 at 16:46
  • +1 'He's done it many times before, on many planets.' This scheme with the Infinity Gauntlet is simply a much more convenient and far-reaching way of doing what Thanos has already been doing for a very long time. He is convinced that what he is doing will make the universe 'grateful'. Commented Dec 18, 2018 at 10:50
  • Which now makes me wonder something incredibly dark and cold................will the Avengers take their revenge on Thanos BUT eventually (at least some) of them understand WHY he did what he did, and thus look for an ALTERNATE way to achieve what Thanos wanted, without threatening life..........? Side question, and I can post that as a question if the SE gods wish. Commented Dec 18, 2018 at 22:47

This is just a speculation

He doesn't... That's why he's called the Mad Titan. He purely speculates and believes himself, also he believes he's the only one who can actually do it.

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    He states that Gamora's homeworld was living in prosperity now that their population was reduced to half. And on Titan, they did not take his advice and the planet seemed ruined. Also, the movie version of Thanos was much more different than the comics, he did not appear as mad and power-starved. Commented May 7, 2018 at 13:01

This is also speculation.

It's not a gamble at all. The infinity Gauntlet with all six stones can do anything, or undo anything - he has a big fat 'Control-Z' button right there on his fist. So if it doesn't work he can undo it immediately.

That being said, he's also done this in microcosm on many planets (like Gamora's) and has been doing so for decades; so, he does have precedent. As for why he did that when he couldn't undo it, Thanos is just the sort of guy to risk whole worlds if it means that he knows his plan for the galaxy works.


Well, Thanos can't be certain. But he does have evidence, and an equation.

THANOS: "I saved you."

GAMORA: "No, no, we were happy on my home planet."

THANOS: "Going to bed hungry. Scrounging for scraps. Your planet was on the brink of collapse. I was the one who stopped that. You know what’s happened since then? The children born have known nothing but full bellies and clear skies. It’s a paradise."

GAMORA: "Because you murdered half the planet!"

THANOS: "A small price to pay for salvation."

GAMORA: "You’re insane."

THANOS: "Little one, it’s a simple calculus. This universe is finite, its resources, finite… if life is left unchecked, life will cease to exist. It needs correcting."


THANOS: "I’m the only one who knows that. At least I’m the only who has the will to act on it. For a time, you had that same will."

Thanos is confident that his plan makes him the saviour of the universe.

THANOS: "With all six Stones, I could simply snap my fingers. They would all cease to exist. I call that... mercy."

DR. STRANGE: "And then what?"

THANOS: "I finally rest. And watch the sun rise on a grateful universe. The hardest choices require the strongest wills."

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