So you built a time machine and used it to stab Hitler. The bad news is, that’s always the first thing anyone with a time machine does. And as Hitler survived, well, it never works. Which both explains why there were so many (failed) attempts against Hitler’s life, and why no one did anything else than trying to kill Hitler with a time machine ever.
But let’s assume that you did manage to do it. Then, Hitler never created the Third Reich, and you have no motivation to go back in time to kill Hitler, and the Universe implode under the paradox.
You monster.
But let’s assume that you manage to change History without Universe-destroying paradoxes. Then without organized nationalist extremists, Communists take power in Germany, giving USSR a foothold in Western Europe. Years after, USSR launch an invasion of all Europe, where most countries fall against the countless human waves USSR launch against them, as well as internal Communist uprisings, until things more or less stop in a bloody slog, where Britain, Norway and Sweden being more or less the last European democracies left. Then, thanks to the many German scientists USSR could get their hands on, USSR develop the nuclear weapon and use it to crush the remaining European countries.
Without a horrible nationalist dictatorship to be at war with, xenophobic nationalist American groups grow more and more out of control. After the Japanese attack at Pearl Harbour, those groups focus against those of Japanese origins, and soon all of Asian origins. The war ends with a massive invasion of Japan homeland, causing countless millions of deaths among both military forces as well as Japanese civilians, as Japan refuse to surrender until the very end. American occupation of Japan is particularly brutal, as xenophobic nationalists are becoming the first political power in the US.
Meanwhile, both in USSR, USSR-occupied Europe and the US, Jewish population is more and more persecuted as there was no systematic, industrial extermination to give antisemitism its bad rep.
Meanwhile, the US manage to copy the atom bomb. Stalin figures that he should attack the US before they can have a big enough stock to be threatening, and launch a nuclear attack backed up by a massive conventional attack. But the US managed to build more bombs that he thought, and use it to repel the attack at great cost, and launch a limited nuclear retaliation against USSR cities. The conflict continues as both sides try to rush new nukes and use them to gain an advantage, until both are exhausted beyond recovery, littered with radioactive ruins.
Then China manages to get their hands on nuke plans, build their own and use them against Taiwan, Japan and Indochina.
Then South American dictatorships get their hands on nuke plans too, and begin to lob at each-other and at political opponents.
Then a secret Italian base in Antarctica, populated by Italian scientists and Fascist officials who slipped away during the whole mess, develop a long-range stealth bomber and use it to lobe their own version of nukes on pretty much everyone, until a breach in the Uranium refinery unit destroys it.
Then a secret Imperial Japanese base on the Moon, helped by the Italian scientists who managed to flee their base destruction through an Earth-Moon rocket, develop an He3-powered laser to try and reconquer Earth, but after a test-fire slag the entierety of China, India and Afghanistan, the laser blows up, causing a He3 chain-fusion on the Moon and breaking it in half.
You monster.
Also, stabbing a given person - Hitler here - isn’t like stabbing a random person in the street. Unless said person was Archibald Hitler, accountant at the local shipping company, widower with four children.
You monster.
Oh yeah, relativism. Eh, personally I have no idea if good and evil are objective and subjective. It even depends on how you define objective and subjective. Be it with or without a guarantor like God, If you can establish rules that take into account the person’s education, situation, culture and such, is it still objective (outside rules) or subjective (it takes into account the person’s subjective position)?
Anyway, as long as it is recognisable enough for me to take action, I don’t care that much.
