Ab Snopes burn barns primarily as a means of getting back at those who've slighted him. As a man with virtually nothing—due largely to his own laziness and drunkenness—his campaign of serial arson is his way of exacting revenge on those much wealthier than himself. So, there's definitely an element of class war here. Snopes is at the bottom of the pile, both socially and economically, and those whose property he destroys are much further up. Burning their barns brings them, to a certain extent, down to his level.

Burning barns is also a way for Snopes to make a clean break. Once he's burned down a barn, he gets his family together and ups sticks and moves on to another town. Snopes knows that once he's burned a barn there's no way he can continue to stick around, and that's just how he likes it. He's a man who doesn't like being tied down for any appreciable length of time, and in some funny kind of way, barn burning gives him some measure of freedom.

As for whether or not Snopes's actions are justified, the answer's very simple: they're not. There's no justification whatsoever for carrying out such serious criminal acts. Arson isn't just criminal damage; it also puts people's lives at risk, and there's never a good reason to do that.

Whatever he may think of himself, Snopes isn't some kind of sturdy individualist standing up to the petty rules of society; he's a lazy, ignorant, selfish drunk who treats his family like dirt and has no conception of social responsibility. This makes him a very dangerous man indeed and his criminal actions all the more contemptible.

The other responses are well-supported in the text, but one could argue that despite Snopes’ obvious flaws, his penchant for barn burning is somewhat understandable.

Abner is an impoverished tenant farmer who was likely born into poverty. In a post–Civil War South, Abner probably had few opportunities to advance his station in life, which trapped him in a place he resented. As a result, Abner resents the wealthy landowners for whom he works because they, unlike him, were likely born into wealth. Because he lacks any real power to change his lot in life, Abner seeks power in destruction.

To him, burning down the burns of the wealthy is righting the wrongs he has suffered under the rigid class structure of the South. While it’s easier to say Abner’s rage is misplaced and his arson habit is absolutely immoral, one could argue that Abner is protesting social injustice in the only way he knows how.

I suppose some latitude can be given to individual readers about the exact reason for why Abner Snopes burns barns. Abner doesn't tell anybody his motivations, and the narrator doesn't tell readers an explicit and concrete reason for Abner's actions; however, we do know that Major de Spain's barn is not the first barn to be burned down by Abner. The story opens with Abner being accused of burning down Mr. Harris's barn, and Sarty is asked to testify. Sarty admits to readers that he is going to have to lie for his father again.

He aims for me to lie, he thought, again with that frantic grief and despair. And I will have to do hit.

I don't think that Abner burns barns because he's a pyromaniac or anything like that. I believe that he probably leaves more barns unharmed than harmed; however, Abner does have a chip on his shoulder about class divisions. This is probably why he deliberately tracks poop into Major de Spain's house.

Watching him, the boy remarked the absolutely undeviating course which his father held and saw the stiff foot come squarely down in a pile of fresh droppings where a horse had stood in the drive and which his father could have avoided by a simple change of stride.

Abner hates his station in life, and doing those sorts of things is his way to get a little bit of revenge against those people he believes are luckier or more fortunate than he is. Abner's barn burning is likely just his next level of revenge. Abner burns down the barn of somebody that he believes has wronged him or insulted him in some way. I do not believe that Abner is justified in burning down another person's property. It's vandalism on a grand scale, and I simply do not believe vandalism is ever justified.

Abner Snopes is an angry, vengeful, and low-economic bottom feeder.  He doesn't respect anyone or anything.  He joined the army, not to be patriotic to a cause, but to see how much loot he could steal.  "The barn-burning of the story's title refers to Snopes's habit of setting fire to the property of those who (in his eyes) slight him.  He perceives that someone insults him or slights him in some way and he decides to get revenge by burning their barn to the ground.  I don't think there is ever any justification for taking away things people have worked hard to build.  I believe strongly that if you want something that someone else has you should go out, work, and earn it.  Snopes beat his family, stole from people, cheated and destroyed the work of others.  He was not justified in any of the negative things he did.