In the story lord of the flies, why is jack act so viloently in front of the others?
The two leaders who emerge on the island are Ralph and Jack. Obviously, they have different leadership styles. Ralph, chooses to "rule" with logic and reason. He appeals the boys' sense of what is necessary to survive and get rescued from the island. Jack, who just wants to have fun, rebels at this. His "let's just have a good time" philosophy appeals to the boys (go figure!) more than the collect the food, build the shelters, keep the fire going boring work that Ralph keeps emphasizing. Jack, through his tough guy personality is the one who hunts the pigs, paints his face, and neglects what Ralph considers the priorities for the group's survival. This breakdown in communication results in violence when Jack's group separates from Ralph's, which eventually dwindles to just Ralph and Piggy. Piggy's glasses are the fire starters on the island. They are stolen by Jack's group in a raid on their camp and Jack cruelly leaves Piggy without the benefit of sight--both literally and figuratively since Piggy has been cast as Ralph's second in command and voice of reason.
Jack wants to establish himself as leader, and to set himself in opposition to the other leader, Ralph. If the latter represents "civilization" in that he wants to build an organized community, Jack represents "savage"--a pre-civilized community of men based on brute force. This is what enotes says about Jack: "Significantly, it is Jack who is the first of the older boys to see the possibility of the beast's existence, and ultimately the ways to use the fear of the beast to his advantage: as a motivation for hunting, and as a means of keeping the littluns under his control. When Simon seeks to expose the beast as just a "dead man on a hill," he is killed by Jack's group." See the rest of enotes analysis of Jack at the URL below.