Golding's notion is that good intention often bring bad results. How do Ralph's good intention fail and why?
Ralph's good intentions are to guide the boys with reason and logic so that they can survive peacefully until they are rescued. In the first chapter, he is elected to be chief because he is the one who has the conch and who first gathers the boys together by blowing into the conch - though he had no such intent when he blew into it the first time. He quickly realizes that the boys need to explore their island to find out what is there and then to build a signal fire so that they might be rescued. He soon also realizes that some duties will have to be delegated since he can't do everything, so Jack volunteers to be in charge of hunting and getting meat. Ralph tries to organize the boys to build shelters for all of them. Ralph always has good intentions, but he does not understand some basic human motivations and that makes him a poor leader. He does not understand that the boys, especially the little boys, do not use the same reason and logic by which he operates. The little boys in particular, are motivated more by instant gratification such as having fun. They are also motivated by fear - fear of an unknown "beast" and fear of Jack. Jack makes promises to the boys, telling them he'll provide them with food, protection from the beast, and with fun. He gives the boys what they want, or at least what they think they want and certainly, he tells them what they want to hear. Ralph tries to be too open, honest, direct, and reasonable. All these methods fail with the little boys.