No Stupid Questions

A death match between the presidents / prime ministers of the rival countries. The country of the winner of that match will win the war, and the country of the loser has to deal with the following consequences.

You'll have to find a way to eliminate greed

Edit: or no people so you have nobody to start wars

Economic democracy; if money and resources cause wars then why not let everyone have control? I will probably hear the human nature stuff but being social is just as if not more important than hurting your species/society.

Humans need to evolve to a state where love, compassion and being helpful to others is ingrained. At the moment we're just clever beasts.

Sadly though, I don't think we have enough time.

An unfortunate combination of somehow achieving a post-scarcity, non-capitalist society with robust resource and population control.

But people are greedy and want "freedoms" that run counter to this.

Make tea

Post scarcity, de-population, or colonization of new worlds.

It would take way more but the first step it would be to remove religions. And not only because most are not peaceful in principle but also because some religions see others as a target. Even small difference in beliefs could spark a vicious and long standing conflic, like Catholics Vs protestants.

Put the ones in charge to the front line.

Abolish Money and increase global distribution of goods aka socialism.

Create an Artificial General Intelligence with the sole purpose of satisfying people's values through friendship and ponies.

The only way to end all wars is for all people to fully control the instinct of domination with rational mind. It's all about education and self-awareness. Making people rational creatures

I think the solution is to have enough renewable energy for all of humanity.

this is a bit grim but global-wide information control that shreds any information which will help the growth of the idea of overly patriotic but less enough to not kill the domestic culture (but i think, not necessarily always telling the truth). that will also promote the sense of global village and transnationalism. and relocate the idea of war to other rivalries like on sports or something, idk.

basically limit the free will without showing it. I can't think if it's gonna happen or this even possible.

Let's first address all the "nature" and "biological" not-really-true claims.

The Batek people of Malaysia are so averse of killing other humans that refuse to do it even when threatened with slavery https://peacefulsocieties.uncg.edu/societies/batek/

So, war is cultural, not biological.

Second, why do we do war?

At first glance, is for scarce resources, for survival.

But look at the modern wars. Are they for survival? Are they for resources that we need to survive?
No they are not.
They are for power.

But whose power?
The power of those who actually have to fight and die?
Certainly not.

The power of the rulers, who are greedy for more power.

Most people need to be scared into going to war, need to be convinced that they are defending their families and their "people".

This is why rulers work very hard to build national identities, the good "us" vs the evil "them".

Here we need three things:

1. We need a culture that knows how to recognize those greedy for power, those with a desire to dominate, and see them as the threat to freedom that they are, ie some sort of https://en.wikipedia.org/wiki/Leveling_mechanism
   There are several cultures that do that, but it has to be a deliberate and conscious thing.

2. We need to rethink our identities, national and not, because those identities are used to define the "other" that is ok to harm and kill.
   A way to do this is to make sure that people who want to travel and visit other groups can do so easily: this will help the various groups understand and humanize each other.

3. We need a culture that stresses the importance of non-violent conflict resolution.
   Because if all you know is violence, then that's what you will use.

I mean, easier said than done of course, but I think that knowing the direction makes it easier to reach it.

For further reading on the subject, I would recommend Bob Altemeyer's "The Authoritarians" and Graeber & Wengrow's "The Dawn of Everything" from the top of my head.

Well effectively, it would entail an all-encompassing global spying machine that gathers all data possible, and imprisons anyone who deviates from the expected baseline. (Wouldn’t end well for me either.) You have to remove most individuality to remove reasons for fighting. And even if you imprison 999 false leads to capture just one instigator, that’s the only way to ‘guarantee’ a fairly high level of security.

So what I’d say we need is 1984 or Мы levels of oversight to have any chance of curtailing conflict for good.

EDIT: oh, and re-education. Lots and lots of re-education.

Simple. We make war illegal.

Establish a global trade network in a way that everyone is completely dependent on everyone else.

Education for everyone globally. War is, like all kinds of violence, an act or reaction of impotence (psychological term/not sexual).

It basically means nobody actually chooses to act violently or start wars. They do it because they believe consciously or subconsciously that they have no other options, because they can't think of any options.

This is always a wrong assumption, because there is always a better option. The difficult part is to getting people to understand their actual options. Education solves this.

Make the old men fight each other and soilder just refusing to follow orders that seem stupid

Easy enough, we just build a jail so big that we can fit the entire world inside of it, boom no more crime.

It's (theoretically) impossible -- you can't break someone's (ignorant and established) will/ideas/plans with words alone or treats. Most world leaders are megalomaniacs by heart, i.e they won't stop until they are done with what they want.

Put everyone in a time-out until they can play nicely with the other children (because let's face it, a lot of them are acting like children)

Did you watch Shiny Happy People? Apparently Christian fundamentalists believe the world population can fit into Jacksonville, FL. There's the answer. Anyone who wants to start a war has to go live in Jacksonville. Build that wall!