What if Hitler would have lived, and rather than execute him, science was able to administer a drug that would eradicate any guilt or pleasure (or both) that he experienced from all his crimes, after which his state of well-being would be increased so that he was able to live in society.
Is that morally acceptable?
There’s not good options here. This would be a great dilemma to put in a novel. It’s like the old intuition pump regarding going back in time to kill the man. Let’s say we did that. You have 3-4 options.
1) Leave the man as-is, hoping the future would play out differently even though at the time he has all the same beliefs.
2) Administer a drug that essentially strips him of his humanity.
3) Kill him.
4) Try to educate him away from his Ubermensch philosophy. Hopefully it would change his belief system, but no guarantees.
I’m not sure if I would feel comfortable making that choice. I think I’d try number 4, and if it didn’t appear to be working, I’d kill him. Number 2 isn’t really morally acceptable. I'm confident number 1 wouldn't work, as our universe is deterministic.
What if the Nazi's had won the war;
After having conquered all their enemies (and the world), Nazism began to flourish, and its people's well being improved dramatically after having been at war for years.
How would you define the "moral landscape" of a world like that?
If the people flourish and the moral landscape is good, then the moral landscape is good. Would that justify the means to arrive at the end? No. I believe there are always other means to achieve the same ends.
A similar dilemma would be to ask; Let’s say Nazism spread across the entire globe via the death of millions. Without the spread, we’d be on our current trajectory, and let’s say we go extinct from climate disaster. But with the spread of Nazism, our world would flourish into transhuman or posthuman society and survive for thousands of years at least.
That’s tough. I’d have to say that Nazism spreading across the globe would be preferable to the extinction of our species. Especially if posthuman status was on the horizon, elevating us enough to see the mistakes of our past.