In Lord of the Flies by William Golding, why does Ralph call a meeting?

Ralph holds several assembly meetings throughout the novel. In Chapter 2, Ralph holds the first official assembly meeting where he tells the boys that they are on an uninhabited island with plenty of fruits and pigs for them to eat. He also tells the boys that they will need to make up rules, such as not speaking when someone else is holding the conch during assembly meetings. Ralph proceeds to explain the importance of maintaining a signal fire and encourages the boys by telling them that there is a good possibility that they will be rescued.
Later on in the novel, Ralph holds another important assembly meeting to discuss how the boys have been neglecting their responsibilities. Ralph mentions that the boys have stopped helping him build the shelters and filling the coconuts with water, and addresses how they relieve themselves near the fruit. Ralph continues to stress the importance of maintaining a signal fire and tells the boys that they need to discuss the existence of the "beast." The boys are unable to come to a definite conclusion in regards to the identity and existence of the "beast," and the assembly ends after Jack and his hunters storm out.