In Lord of the Flies, what logic does Jack use to assure the others that there are no large beasts on the island?

In chapter 2 Jack listens to the littlun who is scared.  What he tells Jack, Jack then repeats aloud to the group.  When the littlun says that there's a beastie on the island, Ralph denies it 5 times.  "But there isn't a beastie" is his phrase each time.

Jack, however, uses a different type of logic.  He says, "Ralph's right of course.  there isn't a snake-thing.  But if there was a snake we'd hunt it and kill it."  Jack uses hunting and violence to show that they are in control and will protect the group of boys.  Ralph gets frustrated because he's the only one denying the beast at all.  Jack keeps saying that they will look for it when they're hunting to make sure.  That makes the littluns feel better knowing that Jack and the boys will fight back and kill it.