"Stalin, Hitler, Mao, (US Senator Joseph) McCarthy - these people have been vilified pretty thoroughly by history," Stone told reporters at the Television Critics Association's semi-annual press tour in Pasadena.
"Stalin has a complete other story," Stone said. "Not to paint him as a hero, but to tell a more factual representation. He fought the German war machine more than any single person. We can't judge people as only 'bad' or 'good.'
"Hitler is an easy scapegoat throughout history and it's been used cheaply. He's the product of a series of actions. It's cause and effect ... People in America don't know the connection between World War I and World War II ...
"I've been able to walk in Stalin's shoes and Hitler's shoes to understand their point of view. We're going to educate our minds and liberalize them and broaden them. We want to move beyond opinions ... Go into the funding of the Nazi party. How many American corporations were involved, from GM through IBM. Hitler is just a man who could have easily been assassinated."
The controversial director's 10-part documentary series for Showtime promises to focus on events that "at the time went under-reported, but crucially shaped America's unique and complex history of the last 60 years." An airdate has not yet been set.
'Empathy for the person you may hate'
Subjects in "History" include President Harry Truman's decision to drop the atomic bomb on Japan, and the origins of the Cold War with the Soviet Union.
"You cannot approach history unless you have empathy for the person you may hate," Stone said during the show's trailer, which promised to put historical villains "in context."
"I don't want to put out conventional History Channel product where it's easy to like it," Stone said.
"He's not saying we're going to come out with a more positive view of Hitler," emphasized professor Peter Kuznick, the lead writer on the project. "But we're going to describe him as a historical phenomenon and not just somebody who appeared out of nowhere."
Stone said that conservative pundits will dislike the show.
"Obviously, Rush Limbaugh is not going to like this history and, as usual, we're going to get those kind of ignorant attacks," said Stone, who also compared the experience of sympathizing with war criminals to making his "W" movie about former President George W. Bush. "I'm trying to understand somebody I thoroughly despised."
The project will also show lesser-known positive aspects of American history and unsung heroes. Stone eventually hopes to send "Secret History" to schools as a teaching curriculum.
"It would be a very different counterweight to what they're learning," Stone said. "Nobody is going to force it down anybody's throat."