Piggy is the social outcast of the group. It is through his character that the true evil and downward spiral toward savagery are shown. A good example of this is when Roger says that he doesn't even see Piggy as a person anymore, but just a 'bag of fat'. This is the exact phrase that they use to describe the wild boars on the island that they hunt. He also represents order and rule. When he discovers the conch shell and shows the others how to use it, it becomes clear that he is trying to still have some sort of human law and rule even on the island. When the conch is smashed, it is symbolic of the final descent by the boys toward animal-like behavior and that all of their civil nature is gone.
