Within Tim O'Brien's novel The Things They Carried (1990), a novel about his experiences as an infantryman in Vietnam, one of the most important stories is "How To Tell A True War Story," and the title does not mean how to tell a true war story but how to tell if a war story is true. An important theme in the novel centers on the difference between what war really is as opposed to how war is perceived by people who do not experience it first hand.
According to O'Brien, a true war story
. . . is never moral. It does not instruct nor encourage virtue, nor suggest models of proper human behavior . . . You can tell a true war story by its absolute and uncompromising allegiance to obscenity and evil.
In other words, if a war story is uplifting, if it is about bravery and self-sacrifice, if it is about personal honor, then we are being told a lie. O'Brien's argument, of course, runs counter to what we have traditionally been taught to expect from war stories, but O'Brien illustrates the truth of his definition with stories--for example, Rat Kiley's torture and killing of a baby buffalo--that are perfect examples of "obscenity and evil."
In addition to being characterized by evil, true war stories are difficult to believe because
. . . often the crazy stuff is true and the normal stuff isn't because the normal stuff is necessary to make you believe the truly incredible craziness.
Even more important, O'Brien argues, there are some war stories one cannot even tell because they are so detached from what the listener expects that they cannot be believed. O'Brien illustrates this by telling a story about a group of men on a listening post in the jungle who think they hear an enemy concert with full orchestra and soloist and, in the background, a cocktail party going on. This, of course, is not possible, but it illustrates the un-real perceptions that men can experience while under stress. Their truth is created by false perceptions, but the experience is true for them at that time and place. O'Brien characterizes this kind of truth by saying that "it's difficult to separate what happened from what seemed to happen." From the soldiers' perspective, what seemed to happen is what happened--and that is where the truth is.
So, the truth of soldiers' experiences in war is what the soldiers perceive, not necessarily what actually happened. In the evil and obscene world of war, according to O'Brien, truth is not part of objective reality--one cannot touch truth; one can only perceive it based on one's own experience.