what do you think are piggy's strenghts and weakness?

Certainly Piggy has a lot of knowledge. He knows things about science that the other boys simply don't know. He knows what to do with the conch, what a signal fire should look like, the relative time of day according to the sun....Piggy also thinks methodically. At one point Ralph wishes he could think "step by step" like Piggy does. Piggy exists on civilization. In a Darwinian Chaotic place like the island, guys like Piggy do not survive. For all Piggy's brains, he is "no leader". From years of torment he has turned into the classic school-yard victim. He doesn't like physical work and really helps himself become an outcast. Piggy is smart but, unlike Simon, lacks insight. Piggy has many qualities yet Golding does' even give him a name. He is worth so much to their society yet is relegated to a source of "derision" because of his physicality and timid personality.

I meant Golding doesn't even give him a name. (3rd to last sentence!)