Piggy represents the rational element in the novel, and, as such, he comes into intense conflict with the more primordial urges of others such as Jack and, especially, Roger.
Concerned with existential questions, Chapter 5 has Ralph, separated now from the others, beginning to question existence:
Again he fell into that strange mood of speculation that was so foreign to him. If faces were differnt when lit from above or below--what was a face? What was anything?....The troube was, if you were a chief you had to think, you had to be wise. And then the occasion slipped by so that you had to grab at a decision....thought was a valuable thing, that got results....
Now, Ralph recognizes thought in Piggy and better understands him as well as comprehending the difference in others who need "fundamental statements" repeated "at least twice before everyone understood them." After Ralph finishes, Jack takes the conch and makes his appeal to the boys, not as a rational one, but an empirical one: "If there were a beast, I'd have seen it."
When Jack finishes, Piggy takes up the conch, but he is not respected by the boys who continue to talk. When he attempts to reason with them--"We know what goes on and if there's something wrong, there's someone to put it right"--no one listens; instead, they make fun of Piggy's stomach. It is at this point that Piggy says there "isn't no fear....Unless we get frightened of people." Here he alludes to the mob and primordial mentality, the baser nature of man that follows the stronger leader. Piggy understands that the more savage nature in mass shuts down all reason--a situation to be feared, indeed.
Clumsy, overweight and nearsighted, Piggy has always been the brunt of jokes and teasing. He cannot get away from this even on the island, just like he is still called by his nickname "Piggy," despite his protestations.
Piggy is intelligent, however, and has more foresight and reasoning ability than the other boys. He contrasts sharply with his rival Jack. If Jack has some important leadership qualities such as bravery, cunning and strength (needed especially to hunt), Piggy is the wiser of the two. However, his physical and social awkwardness don't give him much of a change to prove his worth to the other boys.
Piggy himself is an outcast, ridiculed by everyone. He is, however, intelligent and wise. He has seen in his own life that people can be cruel. Now, on the island, he sees that the problems the boys are facing are created by the boys themsleves. Piggy does not completely figure out that the beast exists in people, as Simon does, but he comes close. He understands people, and he realizes that evil often stems from fear.