In "The Dark Knight," which shattered box-office records in the United States, the late Heath Ledger plays the Joker, who questions whether Batman is ready to kill a villain like him in order to save thousands of others.
"The thing about the Joker that's so good is that he's an agent of chaos and destruction and claims that these are the only two things he can trust and believe in," Bale said at a news conference in Tokyo to promote the film.
The Joker "mocks society's idea of order without having any faith in order. There is a certain amount of truth to what he says, and he's incredibly intelligent," the Welsh-born star said.
"He really knows how to get underneath Batman's skin to the point where he is questioning his own ethic."
Bale was arrested last week for allegedly attacking his own mother and sister in a London hotel after the film's opening in the British capital.
Bale, who frowned throughout the Tokyo news conference and rarely looked up when answering questions, declined to discuss the arrest, replying tersely: "It's a private matter."
Another Hollywood star drunk with too much fame. Hollywood Freaks. If he wants people to concentrate on the film and not his actions then he should've thought of that earlier. You want a routine press conference avoid doing silly things beforehand.