Does Pyle really understand the consequences of his actions in the book The Quiet American?
No, he doesn't. The author makes Pyle so innocent and naive that some people feel it isn't realistic. One of Greene's most memorable metaphors in the book is when he describes innocence as "a dumb leper who has lost his bell, wandering the world, meaning no harm." Pyle's innocence and naivete do more harm than he can imagine. Working undercover for the CIA, he feels that whatever he's doing is justified because it's for the greater good of mankind. His idealistic political views of what the U.S. must do to stop Communism in Southeast Asia allow him to justify the killing of innocent civilians.
The short answer is: No he doesn't. Greene does his best to make Pyle as naive as possible as he stumbles around Vietnam seemingly creating havoc wherever he goes.
However, the reader's knowledge of Pyle comes from Fowler, who is himself a "flawed" character. This begs the question: Can we trust Fowler's assessment of Pyle? Much of this great book is based on the mistrust and cultural misunderstanding between the Americans and the Vietnamese. In the end, it is tough to determine whether or not Pyle's innocence is genuine or a clever disguise.