The conflict between Jack and Ralph increases in chapter 4 because Jack kills a pig, and Ralph is angry that he let the fire go out.

From the beginning, Jack and Ralph value different things.  Jack never quite got over the fact that Ralph was chosen leader.  He considered himself a much better leader and did not think it was right that Ralph was elected just because he was the one that blew the conch.

Nonetheless, Ralph took his duties as chief very seriously.  Keeping the fire going was one of his first priorities.  He felt it was the most important thing they could do to get rescued.  He was not much interested in Jack’s hunting.  Ralph through the hunters to Jack as a bone, a consolation prize for not being chosen leader.  He never took it as seriously as Jack did.

In this chapter, Jack and the hunters get in touch with their heathen sides.  They paint their faces and do war dances around a fire, celebrating their prowess as hunters.  Ralph is more concerned about the fire going out than the pig getting killed.

“There was a ship. Out there. You said you’d keep the fire going and you let it out!” He took a step toward Jack, who turned and faced him.

“They might have seen us. We might have gone home—” (Ch. 4)

On a deeper level, this conflict represents each boy’s inner desire.  Ralph longs for the comfort of civilization, so all he cares about is getting rescued.  Jack appreciates the freedom to be wild and barbaric, so the fire is symbolically less important to him.  He apologizes, but his heart is definitely not in it.  The fire going out, and the ship passing by, is the symbolic end of Ralph’s rule and the beginning of Jack’s.