In William Faulkner's short story, "Barn Burning," the author uses a writing technique that he often favored called "perspectivism," which is defined as:
...the doctrine that reality is known only in terms of the perspectives of it seen by individuals or groups at particular moments.
In essence, this means that for most of Faulkner's short story, the information the reader collects is from Sarty's point of view. We see things colored by his perspective. In the beginning, we know he is illiterate: only by recognizing pictures of food stores does he know what is inside each can. When Mr. Harris accuses his father, at first Sarty thinks of him as the "enemy," however, we quickly learn that Sarty is not happy with the things his father does, specifically situations that require Sarty to lie for his father. Surprisingly, this apple has fallen quite a distance from the tree: Sarty is not like his dad. Whereas Abner Snopes is a vindictive man who believes pay-backs come in the form of barn burnings, Sarty resents his father's actions. Each time his dad does something he should not, the family suffers. At this point in the story, they have to move, again, because Ab is always getting into some kind of trouble.
Sarty is young—only ten years old, but...
...he struggles with moral and intellectual categories...
After all, Sarty is his father's son, and it is said that "blood is thicker than water:" or, because Sarty is part of the family, he is expected to stand up for the family, no matter what. Sarty starts to fight with a boy who insults his [guilty] father. But from within Sarty's perspective, he learn that he struggles with the illegal things his father does. In using perspectivism, Faulkner allows the reader to see Sarty as a sympathetic character.
Sharing Sarty's immediate impressions and judgments forges a strong bond between the boy and the reader.
For a time, there is the interjection by the author of an omniscient narrator—one who has knowledge that Sarty does not have. Sarty believes his father was a Civil War hero, but the omniscient author reveals that he was not the man he has painted himself to have been. The reader has a clearer picture of Ab. If his pyro-maniacal tendencies are not enough, his physical abuse of Sarty, and his verbal abuse of everyone else, gives a less-than-flattering picture of Ab. The reader cannot blame his son for running off—following his conscience instead of perpetuating a family tie with a father who is twisted.
The overall use of perspectivism (from Sarty's viewpoint) allows the reader to understand Sarty's internal struggle coming to terms with what his father does—which Sarty cannot condone. The switch of the narrative's perspective to the omniscient point of view allows the reader to better understand the kind of man Sarty's father is, even if Sarty does not see this completely himself.
Ironically, Sarty has a reliable perception of "the right thing." He hates to move, hates to be verbally and physically abused by his dad. He knows his father's behavior is unreasonable. When he can remain silent no longer, he runs to warn de Spain that his barn is to be burned, and takes a stand against what he knows is wrong—even though it is at his father's hand.
In using this style of writing, we—as readers—are better able to understand the internal conflict Sarty faces, and the importance of the step he takes at the end—his rite of passage into becoming an independent young man of conscience.