Piggy may represent rational thinking as he is logical, but unpopular; eventually Ralph realizes how much he depended on him and his logic, admitting "I can't think. Not like Piggy." He is arguably the most rational boy in the group, and as such his glasses may represent intuition, foresight and intelligence (they can also represent science, as can Piggy). But at times, he may be quite annoying, and usually getting the remark of "Shut up, Piggy!" This symbolism is evident from the start of the novel, when the boys forcibly take Piggy’s glasses to focus the sunlight and start a fire.
When Jack’s hunters raid Ralph’s camp and steal the glasses, the savages subsequently take the power to make fire, leaving Ralph’s group helpless. The physical state of the glasses may also represent the state of the social order on the island, for as their condition deteriorates, so does the order and organization of the boys. Piggy's fatness and asthma, which mark him as an outcast, can also be viewed as emblematic of how the superego, and, thus, civilized thinking, are ill-suited for this environment and are rejected as useless. The power of his glasses to make fire is also a reference to the notion that products of science can be useful, but the science itself isn't. Piggy might also represent Socrates, because, as in Plato's Apology, his high intelligence and plain speaking only create more problems for him, and lead to his eventual death.
Piggy is the most feminine character in the story, and is almost a mother figure for the "littluns". Piggy is physically weak but mentally strong. Piggy identifies the conch, and he and the conch end their existence together. Throughout the story Piggy blames those who do not act properly of "acting like a crowd of kids" and always asks "what would the adults think?" to further enforce his point. In addition, like Piggy, the Sow (‘Pig.' 'Piggy!’) is a sort of mother figure; when she dies, so does most of the power of the conch.
Being physically weak, he is also a symbol of civilized man, in that the others must take care of him. This epitomizes an essential tenet of civilization, which is mercy. As soon as the others abandon him, they are rejecting civilized society.
Piggy's glasses may also represent civilization, as they are used by the boys to light the signal fires, which were the only hope for a return to civilization that they had on the island. When the first lens on Piggy's glasses is broken, it is a symbol that civilization on the island is breaking and falling apart. When the glasses are stolen by Jack's hunters, it is a sign that civilization is completely falling apart.
Piggy's glasses are his source of logical thinking. In most situations when a decision has to be made, Piggy will clean his glasses, to clear his vision. Similarly, Ralph pulls back his long hair from out of his eyes. As the glasses become broken, Piggy, to some degree, makes fewer decisions and becomes irrational in some cases. Without his glasses, Piggy decides to stand up to the savage tribe, and gets killed in the process.