In chapter 6 of Lord of the Flies, why is Simon the only one to question the existence of the beast?
Simon is the only one to question the existence of the beast that the others believe in, as he is more rational and enlightened than the other boys. He is able to think independently and is not so infected with group emotions like fear. However, it is important to realize that he still does believe in the beast in his own fashion. He is the only one to understand that the beast is not the kind of strange monster that the others think it is, but just humanity itself:
However Simon thought of the beast, there rose before his inward sight the picture of a human at once heroic and sick.
Simon's intuitive sense of the bestial side of humanity is of course emphasized by the fact that the monster the boys claim to have seen is in fact a human - the dead parachutist caught on the rock.
Simon, then, understands that the beast which the boys fear is none other than themselves: humanity degraded by its basic, and base, passions. Humanity, as Simon notes, can also rise to be 'heroic'. However, in this novel it is the lower instincts that come to predominate, killing both Simon and Piggy, the other great rationalist, in their wake, and almost overwhelming Ralph, who is one of the few among the boys not to lose a fundamental sense of decency. Ralph is only saved by the timely arrival of a party of rescuers.
Simon's apprehensions about the savage side of human nature are, therefore, borne out by events. However he is not able to share his insights with the other boys, and this considerably weakens his position. He comes across as a rather enigmatic figure on the whole, perhaps even mystical, as underlined by his strange vision in which the Lord of the Flies, in the form of the pig's skull on a stick, appears to speak to him. Piggy, as already mentioned, is also more enlightened than the others, but in a different way: he relies on intellect rather than on intuition.