In my world, a nuclear war back in the 60’s wiped out about 3/4ths of humanity and a lot of the major cities. Civilization was reduced to pitiful outposts, or secluded in underground shelters until it became safe to inhabit the surface again.

I’m trying to have a few battles in the aftermath (around 150 years after the war) but I came up on a problem. In a world where Earth was destroyed by war, why would people still carry on warring each other still? What would be a logical reason for people to still war, even though history shows it can lead to great destruction?

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    $\begingroup$ People don't need much cause for war. They've been warring since before the society, and like will be warring till the end of it. Why? Call it human nature. $\endgroup$
    – Alexander
    Commented Mar 18, 2020 at 2:53
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    $\begingroup$ The Black Death wiped out 30-60% of the population in the affected areas, now have a look at how many wars occurred in the affected areas a few decades after the peak deaths, let alone 150 years later. $\endgroup$ Commented Mar 18, 2020 at 3:22
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    $\begingroup$ Because they need to get the last remaining supply of toilet paper $\endgroup$
    – Shadowzee
    Commented Mar 18, 2020 at 3:31
  • $\begingroup$ Without some sort of conflict or tension, there's not much of a story to tell. $\endgroup$
    – user535733
    Commented Mar 18, 2020 at 3:43
  • $\begingroup$ See the Mad Max movies! $\endgroup$ Commented Mar 18, 2020 at 13:35

4 Answers 4


A has something that B wants, but A does not want to give it to B, and B does not have anything both parties want to trade. Therefore B tries to take it from A by force, A resists, and there you go. Numerous examples from nursery school playgrounds on up to international politics.

  • $\begingroup$ But the logical solution to that problem is to make a compromise, no? Try and work something out. $\endgroup$
    – DT Cooper
    Commented Mar 18, 2020 at 4:15
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    $\begingroup$ @DTCooper if that something is essential for survival, there may be no compromise possible. E.g. iodine supplements for 2weeks or months (until the iodine131 concentration falls to normal). If those supplements aren't in enough amounts for both A and B, logic dictates that if a compromise involving sharing them is achieved, both of them may die; where as if A has it all, his chances of survival increase dramatically. $\endgroup$ Commented Mar 18, 2020 at 5:09
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    $\begingroup$ @DTCooper Historically, even after millions of people have already died in wars, we typically don't arrive at "the logical solution". $\endgroup$
    – parasoup
    Commented Mar 18, 2020 at 6:16
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    $\begingroup$ @DTCooper, where's the compromise in "You have something I want but you also need" against "I have nothing you want"? It's all on you. $\endgroup$
    – Separatrix
    Commented Mar 18, 2020 at 8:35
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    $\begingroup$ @DT Cooper: And what exactly gave you the idea that the majority of humans are logical? $\endgroup$
    – jamesqf
    Commented Mar 18, 2020 at 17:11

Competition for limited resources.

Water that doesn't glow in the dark, someone suggested toilet paper (which was hilarious considering how many rolls my wife picked up to tide us over during this whole COVID19 thing), food (that doesn't glow).

If the choices are:

  • Let my kids die
  • Kill some people and take their stuff

...a lot of "moral" and "reasonable" people will choose "kill and take". People get down right unreasonable when their childrens' lives are at stake. If COVID-19 were killing the youngest 2-4% instead of the oldest, peoples' reactions to it would be quite different I assure you. Mine certainly would be, I have two kids: 9 & 12.


They're side started it, and they need to pay for it, regardless of who "they" are, and any inconvenient facts that might get in the way of conquering the world.

Bat shit crazy

If your only supply of nonradioactive water has a little too much mercury in it, you end up with a society of Mad Hatters. One would have to call into question the ability of a city of lunatics with heavy metal poisoning to wage war, but you might be able to pull it off.

Or maybe the first generation or two had the metal poisoning problem, and the rest is just "the sins of the father" action on a society-wide scale. Sprinkle in some cannibalism during the worst of the madness times for spice, cook at 350F for 150 years, and serve!

Take the United States. England shipped all their religious whack-jobs off to start colonies. Then sprinkle on a hundred+ years of just about everyone with some bad luck and a willingness to take a leap of faith for a better life... tada! Modern USA. Still a non-trivial amount of religious whackos floating about, still down-right puritanical at times about sex & nudity.


In such a war resources will be heavily diminished so people will (have to) fight for them. Then factor in natural greed, because come on look at humanity's current state... And what more reason do you need?

But besides resources you can also have Religion/Ideology that makes Group A hate group B for no reason which for many (again look at humanity's current state) is reason enough to commit genocide.

"Clean" living space, after a nuclear war most of the world will be an irradiated hellhole so areas that aren't "that bad" will become prices and fought for.

  • $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. $\endgroup$
    – HDE 226868
    Commented Mar 20, 2020 at 14:02


Two or more generations have passed since the nuclear war. While little knowledge is being passed on from one generation to the next, the idealism of a higher being had persisted. Those who survive preached the generation after them, and they Believe. Then they pass it onto the next, and so on.

But humans are tribal creatures. They want to form groups with like-minded thinking. Suddenly, they meet another group that does not Believe in their higher being. That alone can spark a war - a religious war.


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