How can you tell which short story is true?Is this book even related to Tim O'Brien?
In terms of factual truth, as the editor above stated, it is impossible to know. But what O'Brien states - and what is really more important than factual truth - is that the emotional truth of what happened is really what counts.
Postmodern theory, and one of its forms, 'creative nonfiction,' which some have dubbed O'Brien's story and novel, posits that 'factual' truth is very difficult to prove. For example, Lt. Jimmie Cross probably would view the events of the opening story of O'Brien's novel quite differently than Rat Kiley or O'Brien himself. So who's to say whose 'factual' truth is correct?
O'Brien forgoes this and decides to focus on the emotional truth of the war - the horrors he saw, the love he felt there, the pain he and his fellow soldiers experienced, the awful things they did, and the burden of the memories that they still carry around.
Readers should keep this in mind while digesting O'Brien's incredible work.
Do you mean factual? The short answer is, no one knows. People have been discussing this since the stories were published.
The more complicated and probably more useful answer is that they are all based on O'Brien's experience of the war, and all of them are things that are intended to be emotionally true...but that to make them more powerful, O'Brien reshaped the facts.