The last 70 or so years have been the most peaceful in human history. How? The American military and economic hegemony. If you want peace, build more aircraft carriers.
There's a reason why the french and the british were so reluctant to start WW2 - the first world war was completely devastating to their societies, and it didn't even improve their security, since Germany was able to relatively quickly rebuild and rearm.
If you want peace, you should build less aircraft carriers and be more pragmatic about immigration.
People around the world are all for the Pax Americana, but only as long as they are granted a shot at the American dream too.
Many people in the US are just banking on the luck of being born within the invisible borders. People elsewhere will resent the US and the entire concept of Pax Americana when they see objectively dumb people having net worths in the 7 figures just because a rising American tide lifts all the American boats while at the same time the Government raises barriers to entry to make it harder for much more worthy would be boat owners to get access to such prosperity.
Germany is pretty much the go to case. They lost WW1, then the American hegemony financially repressed Germany through external debt so they had a pretty good reason to start a new war.
The death of the idea that power and suppression leads to peace is what has stopped world war 3. When WW2 ended, USA immediately turned Germany into an ally and economically supported it as much as it could with the Marshal Plan. It wasn't the aircraft carrier that brought peace, it was cooperation.
Second, the WW2 settlement was far more punishing to Germany than the WW1 settlement. The country was conquered, lost more territory than in WW1, split up and multiple diaspora populations were then pushed in.
I have no idea who teaches this version of history, but it's like saying that the US Civil War started because of States's rights.
The German economy was in full swing by the time WW2 started and Germany had already shrugged off all of its post-WW1 commitments.
The causes of WW2 are complex, but they're well understood today https://en.wikipedia.org/wiki/Causes_of_World_War_II
One major cause is that Hitler came to power. He did take advantage of the bad economy, but that was one rung on the ladder to power, one of the first. He knew he wouldn't get far with it alone, that's why he also recruited the stabbed in the back theory. Ludendorff and Hindenburg were the big promoters of the stabbed in the back theory, because, as the former military leaders of the German Empire in WW1, it shielded them from the consequences of their defeat. Ludendorff elevated Hitler politically and basically saved his life in the Putsch. Then Hindenburg got rid of all controls and gave Hitler total power. If it wasn't for Ludendorff and Hindenburg Hitler wouldn't have risen to some power and then had the keys to Germany handed to him.
Another important cause comes from how the other powers dealt with Hitler. They let him run amok, threaten war, and get his way, time and time again. Until they drew an arbitrary line in the sand (Poland) that didn't make a lot of sense for anyone. Hitler didn't think it was as a big a deal to invade Poland as France and Britain.
Stalin and the USSR contributed to starting WW2, it's not clear that Hitler would have invaded Poland if there hadn't been a treaty with the USSR.
And of course, another key cause of what we know as WW2 is the collapse of France. The war would likely have been contained and Hitler might even have been quickly defeated. That is its own complex topic.
But no. WW2 didn't happen because of economic oppression by the victors of WW1, just like the US Civil War didn't happen because of state's rights.
When nukes came into play, the consequences of violating the peace became too much for any sane state to countenance. The US used nuclear superiority to take on the role of global leviathan.
Despite missteps, it used its monopoly on violence as a very big stick that's allowed for a very lengthy peace. If certain idiot regimes keep playing stupid games, we're going to see what happens when the nuclear stick gets used, unfortunately. That might ensure a century or so of peace, if everything doesn't die.
IRAQ WAR (2003-2011)
WAR IN AFGHANISTAN (2001-PRESENT)
GULF WAR (1990-1991)
VIETNAM WAR (1959-1975)
KOREAN WAR (1950-1953)
This is ignoring an entire array of coups, rebellions, brutal suppressions and subjugations encompassing basically every country in South America
The last 70 years have only seemed peaceful because your the one doing the genocide this time around. Most of the rest of the world would like you to chill.
I could try and argue India is now a better place because the period know as Pax Britannica almost gave them the toilet but you'd rightly consider me a mad man.
Do you think any of the places listed above were improved by being turned in to weapon testing ranges?
"This entry presents an empirical perspective on the history of war and peace. We also published a data visualization history of human violence here on OurWorldInData.org which presents empirical data showing that we are now living in the most peaceful time in our species’ existence."
* Non-war, I think, is a less charged term here, “peace” sounds like an unmistakably good thing, which it isn’t necessarily — or at least there is a long debate to be had about that as well.