Although he is considered an outcast by the boys, Piggy represents the knowledge in this book. He is the common sense behind all of Ralph's decisions. Piggy is the character who has the most important item on the island--his glasses. They represent the fire/signal. Without them, they would not have been rescued. In fact, Piggy represents "vision" in this book because only he can truly see what's happening to the boys. He is the representation of what the adult world thinks. Because he is so different (mature), he is disliked. No one wants to hang around someone who always talks of responsibility, yet that someone can't do much either because of his asthma. That makes him weak in the eyes of Jack and his tribe. Piggy is really the central character who keeps the reader in touch with both the adult world and the lives of the boys and their "games."
Piggy is the voice of intellect in the novel. He and his glasses both represent the thinking side of mankind. In Golding's view that mankind is defective, each person having a beast inside of him that emerges when rules are removed, reason and intellect are doomed because cruelty defies reason. Golding felt that when mankind's cruel nature was unleashed, intelligence is crushed, just like Piggy was crushed by the rock that the completely savage Roger dropped on him. Even at the end of the story, in chapter 11, Piggy still clings to the rules and intellect when he yells at the boys asking them what is better, to be savages or to follow the rules and be civilized. We are shown Piggy's role as the voice of intellect early in the story when he is the one to suggest using the conch shell to summon the others. Throughout the novel, Piggy is the one to make suggestions, to get Ralph, especially, to think and consider situations and actions.
Piggy is a victim because he is clearly someone who is often picked on, early on in the book we realise that he was bullied at school. He is also a victim of jack who is constantly mean to piggy, he always calls piggy fatty and tries to take piggys voice away from him (this is by trying to get rid of the conch). Finally piggy is murdered and dies with the conch due to jack and his tribe.