Jack and Ralph respond in different ways to the ''beastie.'' What do their responses tell us about their character?
Ralph and Jack respond differently to the boys' fear of the "beastie." In chapter 2 when the littlun first brings up the idea, Ralph tries to deal with it in a straightforward and rational manner. He tells the little boy he was just dreaming, and then he repeatedly says, "But there isn't a beastie." Jack agrees with Ralph, but goes further, promising to hunt and kill the thing "if there was a snake." Making empty promises is unethical; Ralph won't do that, but Jack does.
In chapter 5, Ralph decides to address the issue of the boys' fear again. He believes fear is interfering with the boys' happiness, so he wants to settle the issue. He thinks he can reason with the boys, so he open up the meeting to discuss their fear. He takes a democratic approach and seems motivated by wanting the best for the boys. Jack starts out excoriating the boys for being "cry-babies and sissies." He then manages to escalate the boys' fear by talking about animals and beasts. He then sets himself up as the solution: "Am I a hunter or am I not?" He uses the boys' fear to elevate himself.
As much as Ralph tries to keep the discussion under control, it eventually deteriorates to what seems to him "the breaking up of sanity." He is discouraged by the boys' reaction, but still trusts in them to make good decisions, even calling for a vote about ghosts. Jack seizes on the weakness in Ralph's leadership and defies him, shouting, "Bullocks to the rules!" and leading the boys toward the beach in a disorganized, hysterical scatter. Ralph trusts the boys to be logical, but Jack takes advantage of their insecurities to fracture the fragile civilization they've started to create.
Ralph's reaction to the beast shows that he believes in reason and is motivated by what will help the entire society. Jack's reaction shows he knows how to use others' insecurities to grab power for himself.
At first Ralph reacts with disbelief that there is a beast. Given his reasonable personality, he cannot believe a beast would live in this environment. He tries to convince others that the beast simply could not exist on the island. Jack's first response it also one of disbelief. However, he sees how he can use the fear of the beast to undermine Ralph's authority by promising the littleuns that he and his hunters will destroy the beast. Finally, Ralph must give in to the fear of the beast and organize a search party for it. Not realizing Jack's evil intentions to discredit Ralph and take over leadership himself, Ralph takes Jack along. Jack uses the trip to deride Ralph. When the boys finally do see the dead parachutist, neither Jack nor Ralph takes the time to really check out what they are seeing, showing that they are both still frightened boys and not mature men.