At this point in the story, as Jack and Ralph work their way towards the mountain to investigate, there is a battle over leadership. It is subtle but intense as Jack and Ralph basically try to figure each other out. Once Simon goes back to the beach, they continue on and spar verbally as they also decide how they will try to get to the mountain and who is more scared.
When Ralph begins to discuss his worries about it being too dark to hunt the beast properly, Jack mocks him cruelly. This prompts Ralph to simply ask "Why do you hate me?"
Jack doesn't respond; they continue working their way towards the mountain after a long pause. Already there begins to be a shift where Ralph finds that getting the boys to all like him and to go along with what he says because they feel kinship simply isn't going to work. Jack knows that raw emotion and fear and hate are powerful and he clings to them, the things that will eventually place him at the top of the leadership on the island.