The English philosopher to write most on this topic was probably Thomas Hobbes in his most famous book "Leviathan." There's a summary of both the philosopher's views and his works on enotes. Hobbes noted that, whether or not we actually assert that humans are by nature hunters and killers, we appear to believe so in our actions: why else, he asks, would we lock our doors at night? Hobbes uses this as a justification for absolute monarchy, on the grounds that, without an iron-fisted ruler, there is no hope for any sort of social harmony or cohesion. For a contrary view, you might look into the work of the Earl of Shaftesbury, John Locke, or Jean-Jacques Rousseau's "Social Contract". In this work, Rousseau argues that humans often tend toward barbarism in a state of nature, but this tendency is counteracted and balanced by the emotion of sympathy and, for this reason, surpluses have to be created before human turns against human of his/her own accord.
In "Lord of The Flies" Golding's writing definitely pointed to the concept that at our base, humans become more animal like in a life or death situation. The will of man to survive is very strong. Does that mean that each and every man at his core will hunt and kill? Golding certainly believed so, but if you look at all of the characters in the story there are several that died because they could not go to that place inside themselves and Ralph certainly did not. Right up to the rescue Ralph was trying to bring order and peace to the island. Would he have killed to survive? We won't ever know but as he hid in the brush he had a weapon and I think he would have tried to protect himself. One of the main themes of the novel was survival of the fittest and the fact that the innocent Simon was killed, weak Piggy died, and reasonable Ralph ended up running for his life is certainly telling that Golding believed man at his core is no different than the animals when it comes to survival.
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Golding is saying that humans have a tendency towards evil and destruction when put in situations. He is showing a representation of society through the book, but the individuals of society are not the way they are just because. Jack, for example, hates Ralph out of jelousy. Many of the boys join Jack's tribe out of fear, and to gain the illusion of control over their situation.