Hegel wrote that "all great world-historic facts and personages appear twice." It was Karl Marx who said that Hegel forgot to add that these repeating events happen "first as tragedy, then as farce." You know, like Adolf Hitler and Donald Trump.
The script goes like this. A right-wing party is created or taken over by a charismatic populist. Tick. He mesmerises half the country with a constant shower of nationalist and racist lies (more than half the country, in Hitler's case). Tick. Once in power, he proceeds to shred the status quo both at home and abroad. Tick. But is starting a war also a necessary part of the package?
Mr Trump hasn't started any wars yet. He never would start one deliberately, but then Hitler didn't mean to start a big one either. He just wanted to conquer his half of Poland after he made a deal with the Soviet Union, which got the other half. (He'd be back for more later, of course.)
Demanding territory that isn't theirs is a tendency common to both men: Austria, Sudetenland, and the Polish Corridor in Hitler's case, Canada, Greenland, Panama and the Gaza Strip in Mr Trump's. However, Mr Trump's threats are unconvincing. He talks the talk, but he probably doesn't have the stomach for a real fight.
Hitler fought for four years in the trenches of the First World War, was decorated for his courage, and was a street-fighter in the violent politics of 1920s Germany. Mr Trump was born into money (he was a millionaire at the age of eight), went into the real-estate business with his father, and avoided service in the Vietnam War by claiming that he had "bone spurs" on his heels.
This is a showman, not a brave man. There is a small risk that his rash and conflicting promises might trap him into a war, especially since Israel's Prime Minister Binyamin Netanyahu is scheming to draw him into a joint attack on Iran. But even the Republican majorities in Congress would probably baulk at another American military adventure seeking "regime change" in the Middle East.
So no, Mr Trump is probably not going to start a war. Hitler was the tragedy; Mr Trump is the farce. But even farces can do great damage. In this case, the principal victim of his antics will be the international rule of law, a fragile and relatively recent invention that has probably spared us from a nuclear war for the past 80 years.
The First World War killed 11 million people. The Second World War only twenty years later killed between 45 and 65 million. There were even a couple of small nuclear weapons dropped on Japan at the end. That's what happens when you combine traditional great-power behaviour with modern weapons of mass destruction.
Yet here we are eighty years later, and no great power has fought any other great power directly since the Second World War. (Proxies are OK.)
There are now four times as many people on the planet and almost four times as many countries, but the global death toll in international wars across borders (civil wars don't count) has plummeted from a million a month in 1945 to around a hundred thousand a year by 2020.
However, now the numbers are going up again, mainly thanks to the wars in Ukraine and Gaza. They are evidence that the system that protected us for so long is breaking down.
What the international rule of law means is that sovereignty is sacred; that attacking another country is literally a crime. Borders may only be changed by peaceful negotiation; any changes accomplished by force are illegal.
There is no international police force, so nobody may come to arrest the criminal, but the conquest will never be recognised by other countries. There will be sanctions, boycotts, all manner of nuisances -- enough, in most cases, to deter countries from trying to grab some of a neighbour's territory.
It's a flimsy system, but it has served us well for a long time. Lose it and we're straight back to the 18th century -- with nuclear weapons. And taking the lead in demolishing this system are two great powers, the United States and Russia, who probably owe it their own survival through eighty years of relative but precarious peace.
Gwynne Dyer is an independent journalist whose articles are published in 45 countries. His latest book is 'Intervention Earth: Life-Saving Ideas from the World's Climate Engineers'. Last year's book, 'The Shortest History of War', is also still available.
