Piggy is one of four main characters in Lord of the Flies, by William Golding. In this symbolic novel, Piggy is the character who most represents intellect and reason, but none of the boys on the island want to listen to anything he says. This disdain for Piggy and the things he says begins in the first chapter, even though what he says is true.
The first truth he speaks is to Ralph; he says that no one knows they are here, stranded on this island after the plane crash. He mistakenly believes the rest of the world has been destroyed by an atomic bomb, but his declaration of their situation is true, and Ralph does not want to hear it. (In fact, Ralph is equally misguided in his belief that his father, a naval commander, will come find them as soon as he has leave.)
Another truth Piggy speaks is particularly unwelcome to Ralph. He says, “We got to do something.” If Ralph had his way, at least in the beginning, he would have played and swam and done whatever else he wanted without the encumbrance of having to meet and decide and do things. Later Ralph agrees with Piggy and is frustrated by the fact that no one wants to help do the things which they have all decided need to be done.
Another truth Piggy speaks is that the conch which he and Ralph find is valuable. Ralph treats it more like a toy and the others just think it is kind of cool, but Piggy recognizes its value as a symbol of authority and order. Soon after the conch is blown and the boys gather, the boys establish a rule that whoever has the conch has the floor to speak; however, Piggy is shouted down as soon as he tries to exercise that right. As the novel progresses, of course, the conch takes on greater significance, and as soon as the conch is destroyed, so is all semblance of civilization. Piggy was right.
None of the boys like Piggy, and they refuse to listen to him because he is fat, has asthma, and wears "specs." In short, he does not look like a leader, so they are unwilling to listen to anything he has to say and eventually kill him because of that. Throughout the course of the novel, however, Piggy's wisdom is consistently proven to be correct.