In a new interview with The New York Times, the Harvard-educated actor shares his perspective of what really happened during the season 4 premiere of the HBO filmmaking competition, executive produced by himself and Ben Affleck, in which he lectured African-American producer Effie Brown about diversity both behind and in front of the camera.
"Um, there are a few parts to it," Damon, 45, began. "So I'll unpack it for you.”
"Ben and I had taken a lot of stick for this 10 years ago, that our committee of mostly white men had selected three white men, in succession, as winners," he said of the frustration leading up to his remarks.
In order to select a filmmaker, producers partnered with Facebook and recruited at film schools to find the final 20 applicants -- 17 of them were white men.
"By the time we arrived to do our judging, we knew we had blown it, so Ben and I were already frustrated and upset about that," he continues. "So when Effie brought it up, it was like, yes, O.K., we got it."
"The dark secret of Project Greenlight is that the TV show is bigger than the movie," The Martian actor adds. "It costs more than the movie."
Damon continues on, explaining that "the idea that I would say that there didn't need to be diversity behind the camera, it's not only complete anathema to what I believe in my heart and always have, but it's not something that I think anybody would ever say with a camera on."
"And so when Effie was advocating for the woman and the Vietnamese-American guy, what I actually said was, 'Are we judging a contest or are we casting a reality show?'" he continues. "And that's when she said, 'Wow.' And I went, no, Effie, I'm completely serious, what is our responsibility at this point? Because we had already blown it on the competition."
Despite Brown's reaction -- which caused an uproar and plenty of retweets on Twitter -- Damon insists that the two were "fine."
"It wasn't like I left and said, 'Boy, I got in an argument with Effie Brown,' and I don't think she would have left thinking that she had had an argument with me," he explains. "But the truth is, Effie did an awesome job for us. She's an awesome producer."
Unfortunately, this wasn't the only controversy Damon found himself in the middle of in 2015. In an interview with the Guardian, he talked about how actors should keep some "mystery" in their private lives, and seemingly suggested that gay actors should stay in the closet.
"I actually just conflated two stories that I've told a thousand times at junkets, and did it in a really clumsy way," he told the NYT about the interview gaffe.
Back in September, Damon addressed his Project Greenlight comments in a statement given to ET. Hear more in the video below.